C:\Electrical fuse panel instructions\Final instructions\MGB wiring

CUSTOM
WIRING PANEL
FOR MGB
V8 CONVERSIONS
By Dan Masters
DMPublications@aol.com
A dmp PUBLICATION
DM Publishing, PO Box 6430, Maryville, TN 37802-6430
Copyright © 2002, Dan Masters
ALL RIGHTS RESERVED
No part of this booklet may be reproduced in any form,
except for the inclusion of brief quotations in reviews,
without permission in writing from the author or publisher.
NOTE: The material in this manual is provided as an aid to MGB owners who want to do their own work in making an
upgraded wiring system. The author makes no claims for its accuracy or suitability for use, although every effort was
made to make it as correct as possible. The material in this instruction manual should be used with discretion, and is to
be used at the readers risk. This information should be considered general rather than specific to any particular
vehicle, and no warranties exist, either expressed or implied. The material in this manual is to be used only by those with
the requisite knowledge and experience to properly evaluate the material for suitability, and to properly implement the
material. The author is not responsible for mechanical or electrical damage or personal injury directly or indirectly
resulting from material in this document.
CUSTOM WIRING PANEL
Sticking a high-powered V8 in your poor little B? Lots
of horsepower? To go along with all that extra power, have you
added a GM high output alternator, a set of driving lights that will
melt trees, and a super stereo system to keep you company? Is
your poor wiring now leaking smoke everywhere? It’s time now
for some electrical updates as well. At the least, you’ll need to
make some modifications to the wiring to accommodate the new
electrical requirements. At worst, your wiring looks like a bowl
of three day old spaghetti after the mice have been in it. How
much fun can you have with your increased horsepower if the
car’s electrical system won’t let you use it?
To keep the juice flowing as it should, you have a few
options: Patch what you have, replace the wiring harness with a
new one and modify it for your application, or buy one of the
many aftermarket wiring kits now available from various street
rod vendors. Unless the original wiring is in pretty good shape,
patching it will be a never ending task - patch this end today, that
end tomorrow, etc. Buying a new harness will a bit pricey, and
you will still have undersized and under-fused wiring. Most of
the aftermarket wiring systems are, unfortunately, designed for
street rods, and are overkill, having many circuits that are not
needed for the typical British car.
In this article, I propose a new alternative - a home-built
wiring system, specifically designed for YOUR car! What’s new
in this article is not that the wiring is designed for your specific
car, but that YOU can do it yourself. The heart of the wiring
system, the POWER BLOCK (fuse/relay/flasher pane)l, is quite
generic, but with the information in this article, even the
“electrically challenged” should be able to custom tailor the
overall wiring to a specific application.
On pages 4 & 5, I have shown a wiring diagram that
represents how I would wire a 197MGBGT. The shaded area in
the center of the diagram is the generic portion of the wiring, or
what I call the “Power block.” By examining how the power
block connects to the rest of the wiring in this diagram, it should
be pretty easy to see how the connections would be made for
different model or make of automobile.
Power Block as installed in a TR3. In this car, the best location
for the block was under the battery box, behind the dash, but a
suitable location can be found in any car.
CAVEAT: This article assumes a minimum amount of
familiarity with electrical circuits and construction techniques.
If you have any doubt about your ability, it is strongly
recommended that you enlist the aid of a friend with the requisite
experience.
CIRCUIT DESCRIPTIONS:
For the most part, the individual circuits are straight forward, but
some of them need further explanation.
Completed Power Block, ready for installation. The wiring is
coiled up, waiting to be routed as appropriate for your car.
Naturally, in a generic article the size of this one, every
possible configuration/preference can’t be addressed, but if you
will write to me with your requests, I’ll try to address the most
popular requests in a future revision. For example, if enough
people request information on retaining the existing hazard
switch instead of the switch I have proposed, I will provide a
circuit for that. Nevertheless, with the information supplied
herein, you should be able to create a custom wiring system that
will satisfy even the most finicky owner.
Fuel pump circuit: This circuit is to be used only if you opt to
replace the mechanical pump with an electrical pump. The relay
for the fuel pump is operated whenever the ignition key is on, but
it has a couple of safety features. The relay will operate only if
both the inertia switch and the cutoff switch are closed. The
inertia switch will open whenever the car is subjected to a hard
jolt, such as in an accident, preventing fuel spillage if a fuel line
should be ruptured.
The cutoff switch (optional) provides for a small bit of
theft protection. This switch should be hidden from view, but
easily accessible. If this switch is open, the pump will not
operate, and the engine will die in a very short distance when the
fuel in the float chambers is exhausted, leaving the thief stranded
in the middle of the street.
To prevent embarrassment to yourself if you should
forget to turn the switch back on before starting your car, the
normally closed contact of the relay sends power to the warning
buzzer. Additionally, if the inertia switch should actuate from a
hitting a pothole or such, the buzzer will also sound, reminding
you to reset the switch.
If you prefer, you may omit the fuel pump relay and just
wire the pump directly to fuse G3, using a 28 strand green wire.
You can still wire the cutoff switch and the inertia switch if you
1
wish, wiring them in series with the fuel pump, but you will lose
the warning buzzer function. Eliminating the relay frees up one
relay space, which can then be used for the optional driving light
circuit, or for the overdrive circuit, if you are using a type “A”
overdrive in an otherwise stock MG.
Driving lights (optional): Operating the driving light switch
applies ground to the relay coil, which receives power from the
high beam position of the headlight dimmer switch only if the
high beams are on. Wired this way, the driving lights are on only
if the switch is on AND the high beams are on. When you switch
to the low beams, as when meeting a car, the driving lights
automatically go out as well.
Headlight fuses: If you’ll notice, there are none! I am
STRONGLY opposed to the use of fuses in the headlight circuit.
Having the headlights go out while doing some spirited driving
on winding back road on a moonless night because a wire
momentarily bounced into contact with ground can be fatal!
Hazard switch: Do yourself a favor and discard the stock hazard
switch. The majority of turn signal problems are due to faulty
hazard switches. Replace it with a DPDT (double pole, double
throw) switch from Radio Shack or similar, and wire it as shown
on the “typical” diagram. Just be sure NOT to get one with a
“center off” position, as neither the turn signals nor the hazard
flasher will work with the switch in the off position.
Cooling fan: I have provided two options for this circuit. If you
prefer that the fan run only when the ignition key is on, wire
terminal 85 of the relay, using 14 strand green wire, to the “B”
terminal of the turn signal flasher. If you want the fan to run
whenever the thermostat calls for it, ignition key on or off, wire
terminal 85, using a 14 strand purple wire, to terminal “B” of the
hazard flasher.
Overdrive circuits: The wiring diagram included with this
article has provided for a “J” type overdrive unit, just in case
anyone wants to use this panel in a stock MG. If you are using a
V8 and a 5-speed, you can just eliminate the wiring for the OD
unit. If you are wiring up an earlier MG with an “A” type OD,
you will need to add a relay. making a total of seven. If you add a
relay, the panel will have to be lengthened by 1 7/32” to
accommodate it. On page 8, I have shown just the pertinent
portions of the wiring that will have to be modified for the relay.
Power relay: The sole purpose of this relay is to take the load off
the ignition switch. Using the relay, however, gives an
opportunity to add a modest theft protection as well. By wiring
the relay coil ground connection through a simple ON-OFF
switch, the ignition circuit can be rendered inoperable by
opening the cutout switch. This cutout switch is redundant if you
opt to use the fuel pump relay cutout switch, but if you retain the
stock mechanical pump and don’t use the relay, the power relay
cutout switch will serve in it’s stead.
One important consideration to be aware of with this
circuit: it is imperative that you DO NOT connect the alternator
warning light lead to the relay terminal 85. If you connect the
warning light lead to terminal 85 the engine will continue to run
even when you turn the ignition key off. Current from the
alternator through the warning lamp is enough to keep the power
relay energized.
WIRING CONNECTIONS:
Wires leaving/entering the power block are to be connected as
2
described in the functional descriptions below:
Note: the first letter(s) below indicate the wire color code, and
the following numeral indicates the wire size in accordance
with the British wire standards. Unlike American wire which is
sized by gauge, British wiring is sized by the number of
0.30mm strands contained within the wire.
Color codes:
N Brown
U Blue
R Red
P Purple
LG
W
Y
S
Light Green
White
Yellow
Slate
G
B
K
O
Green
Black
Pink
Orange
Wire size:
9 =9 strands - rated to carry 5.75 amps
14 =14 strands - rated to carry 8.00 amps
28 =28 strands - rated to carry 17.50 amps
44 =44 strands - rated to carry 25.5 amps
65 =65 strands - rated to carry 35.00 amps
84 =84 strands - rated to carry 42.00 amps
120 =120 strands - rated to carry 60.00 amps
B-9: Ground connection.
BG-9: Connects to the thermostat/switch for the cooling fan, and
is grounded to operate the fan relay.
BW-9: Ground for the power relay. If you wish to use the anttheft provision, run this wire to ground through a hidden switch.
BY-9: Grounded to operate the fuel pump relay. If you choose
not to use an inertia switch or a cutoff switch, this wire should be
connected directly to ground.
G-14: Provides power to loads that are operable only when the
key is on. Typically supplies power to the windshield
wipers/washer, gauges, brake failure lamp, and low oil pressure
lamp. Maximum load on this wire should be less than 8 amps.
G-28: Provides power to loads that are operable only when the
key is on. Typically supplies power to the heater fan, brake lights,
reverse lights, and, if applicable, the overdrive unit. Maximum
load on this wire should be less than 15 amps.
LG/N-14: Feeds the turn signals, and should be connected to the
LG/N wire coming from the turn signal switch in the steering
column. Maximum wattage for the TS bulbs should be 27 watts.
(typically, 1157 bulbs)
LG/R-28: Power to the fan indicator lamp when the fan is on.
This is optional, but is recommended.
N-28: Provides power to the “BATT” terminal of the ignition
switch.
N-120: Main power feed from the alternator/battery. This wire
carries ALL of the current used by the car.
NR-14: Provides power to the headlight switch.
P-14: Provides power to loads that are operable with the key on
or off. Typically supplies power to the “flash-to-pass” switch,
clock, courtesy lamps, and memory power for the radio.
Maximum load on this wire should be less than 8 amps.
P-28: Optional accessory power. This lead could be left as a
spare, provide power to a lighter socket for plug-in accessories,
or provide power to a stereo amplifier. Maximum load on this
wire should be less than 15 amps.
wire should be less than 15 amps.
PB-9: Grounded by the horn button, and operates the horn relay.
PN-28: Supplies the flasher voltage to the turn signal lamps, via
the hazard switch. See text for details.
PY-28: Supplies power to the horns when the horn relay is
operated. The other side of the horns should be grounded.
Maximum current on this wire should be no more than 15 amps.
R-14: Provides power to the parking/marker lights, and to the
dash lights via the dash light dimmer.
RG-14: Power from the headlight switch to the fuse for the
parking/marker and dash lights.
need to replace them. It helps to have “finger room” so you can
get a good grip on them.
If you wish to use a 3 instead of a 2 terminal flasher for
the hazards, with a separate indicator to let you know the flasher
is working, you will need to move the flasher mounting holes
back from the edge by 3/4”, because the 3 terminal flashers are a
bit longer. If you are using separate indicators for right and left
turns, as stock, you won’t need a separate hazard indicator.
You can use either screws and nuts or rivets to fasten the
components in place on the panel. If you use screws and nuts,
you will have to use special “clinch” head screw on the relay
sockets, as there is little clearance for the screw heads when the
relays are installed. If you use rivets, you will have to modify
your rivet gun a bit to install the relay sockets - there isn’t room
for a standard rivet gun nose. See the photo below for details.
S-14: Connects to the optional fuel pump warning buzzer. See
text for details.
UR-14: Power to the headlight low-beam relay from the dimmer
switch.
UR-28: Power to the headlight low-beams from the headlight
relay. Low beams should be a maximum of 90 watts each.
UR-14: Power to the headlight low-beam relay from the dimmer
switch.
UR-28: Power to the headlight high-beams from the headlight
relay. High beams should be a maximum of 90 watts each.
W-14: Input to the ignition side of the alternator warning light
from the power relay.
W-28: Provides power to the ignition coil.
WG-9: Operates the ignition relay from the ignition switch.
YN-28: Provides power to the cooling fan. Maximum load on
this wire should be no more than 15 amps.
YR-28: Supplies power to the fuel pump. 15 amp Maximum.
CONSTRUCTION DETAILS:
Panel: The wiring panel (see page 12) is made from a piece of 16
gauge steel, purchased from a home building supply store such
as Lowes or Home Depot. For ease of fabrication, it is designed
as a flat sheet, which means you will need to use spacers or other
form of stand-offs to accommodate the fasteners used to hold the
components on the panel. If you want to be real fancy, you could
make the panel with feet, eliminating the spacers.
This particular size and shape is just a suggestion, and
you can modify it to fit if you have a particular location in mind
for your own panel. You could separate the fuses from the relays
and flashers, and make the panel in two pieces if you wish.
The location of the holes for the flasher and relay
sockets was deliberately planned to allow the flashers and relays
to stick out from the panel so that they would be easy to grip
when you need to replace them. In general, these components are
a tight fit in the sockets, and a bit of force is needed to remove
them - they can be hard to remove in tight quarters when you
Modifications required to the rivet gun to rivet the relay sockets
in place. Clinch head screws will eliminate the need for this.
Relays: Standard 5-terminal SPST automotive type relays are
used for everything except the fuel pump relay. The difference
between a 5-terminal and a 4-terminal SPST relay is that there
are TWO output terminals, both having an “87” designation. If
you can’t find 5-terminal SPST relays, you might get by with 4terminal relays, but it is a bit difficult to attache two larger size
wires to one terminal. Using relays with two output terminals
alleviates the problem. Just make sure the relay you get is indeed
a SPST, and not a SPDT (which has “87” and “87a” output
terminals.
For the fuel pump, you will need a SPDT relay, often
referred to as a “changeover” relay. This relay has a normally
open and a normally closed contact. The normally closed contact
(87a)is used for the warning buzzer circuit. If you should
inadvertently use one of the standard SPST 4-terminal relays in
the fuel pump circuit, the only problem will be that the warning
buzzer won’t work - all other fuel pump functions will still work
ok. If you use a SPST 5-terminal relay instead, the buzzer will
sound when the pump is ON, not when it is off.
Fuse Blocks: When you buy your fuse blocks, they will come
with four individual terminals and one “bus bar” with terminals
for four fuses, as shown below. For the “purple” fuse block, use
the four terminal strip intact. For the “green” fuse block, you will
need to cut the strip as shown. Three of the terminals will supply
power to the “green” loads, and the fourth will be used for the
parking light fuse. When you cut the strip, be sure to remove
3
ALTERNATOR
IGNITION WARNING LAMP
NY - 14
W - 14
amber
15A
(as supplied)
N - 28
B - 28
RADIO
CLOCK/PRESET
MEMORY POWER
GM
ALTERNATOR
N - 120
-
WP - 28
P - 14
IGNITION
SWITCH
ACC
START
WR
28
BATT
WG - 9
IGN
+
W - 28
85
87 87
86
30
W - 14
N - 44
PK - 9
LH DOOR
SWITCH
BATTERY
B-9
RF PARKING
LAMP
B-9
KEY WARNING
BUZZER
R - 14
STARTER
POWER
RELAY
P - 14
PG - 9
LF PARKING
LAMP
N - 28
N - 28
P - 14
R - 14
N - 44
RF MARKER
LAMP
N - 120
B-9
R - 14
B-9
R - 14
N - 44
ANTI-THEFT
CUTOUT SWITCH
N - 28
POWER
TERMINAL
N - 28
BW - 9
R - 14
LF MARKER
LAMP
HEADLIGHT
SWITCH
P - 14
P - 14
CLOCK
R - 14
B-9
RG - 14
CIGAR
LIGHTER
U - 14
B-9
LICENSE PLATE
LAMP
R - 14
B-9
P1
COURTESY LAMPS
& SWITCHES
P - 28
P - 14
B-9
P2
P - 28
P - 14
P3
15A
B-9
10A
RR TAIL
LAMP
NR - 14
R - 14
B-9
15A
RR MARKER
LAMP
P - 28
P - 14
R - 14
LR TAIL
LAMP
PW - 9
PW - 9
(N)
(NR)
PW - 9
R - 14
UR - 14
B-9
(UR)
LOW BEAMS
LICENSE PLATE
LAMP
B-9
(UW)
LR MARKER
LAMP
DIMMER
SWITCH
R - 14
B-9
B-9
4
86
30
87
87
B-9
HATCH LAMP
& SWITCH
UW - 14
RW - 14
UR - 28
B - 28
UW - 28
B - 28
UW - 28
HIGH BEAMS
86
87
30
30
87
87 87
UR - 28
UW - 28
RW - 14
B - 28
85
UW - 28
RW - 14
LOW BEAMS
RW DEFROST
RW - 14
B - 28
HIGH BEAMS
RW - 14
CIGAR
RW - 14
UW - 14
HIGH BEAM INDICATOR
HAZARD
OIL
RW - 14
CLOCK
RW - 14
B - 14
HEATER
RW - 14
GAUGE LIGHT
DIMMER
FUEL
RW - 14
UR - 28
RW - 14
UR - 28
RW - 14
VOLTS
WATER
TACHOMETER
SPEEDOMETER
PW - 9
R - 14
RW - 14
85
PY - 28
WIPER/WASHER
SWITCH
W - 28
B-9
(GK)
G - 14
IGNITION
COIL
(ULG)
ULG - 14
(R/LG)
(NLG)
(B)
R/LG - 14
NLG - 14
WIPER MOTOR
B - 14
G - 14
(LGB)
FUEL GAUGE
GB - 9
G - 14
WATER
TEMP
GU - 9
G - 14
OIL
PRESSURE
YP - 9
G - 14
TACHOMETER
G - 14
VOLTMETER
G - 14
DISTRIBUTER
G - 14
B-9
10A
G - 14
WB
28
G - 28
G - 28
B
28
15A
BACKLIGHT HEATER
& SWITCH
G - 28
10A
G - 28
R - 14
TO
IGNITION COIL
MINUS POST
WASHER
MOTOR
AFTERMARKET GAUGES
G - 14
LGB - 14
YG - 9
G - 28
10A
HEATER
SWITCH
(GY)
POWER
BLOCK™
30
86
87
87a
G - 14
WARNING
BUZZER
GP - 28
BRAKE SWITCH
AND LIGHTS
G - 28
15A
B-9
LOW OIL PRESSURE SWITCH & LAMP
B-9
YR - 28
BW - 9
BW - 9
WB - 9
G - 14
HEATER FAN
S - 14
B-9
BRAKE FAILURE
SWITCH & LAMP
(B)
FUEL PUMP
85
B-9
GP - 28
B-9
B-9
FUEL
PUMP
P - 28
INERTIA SW
BO - 9
OD
SWITCH
85
30
87
87
86
P - 14 OR G - 14
SEE TEXT
COOLING FAN
BY - 9
B-9
YG
28
TURN SIGNAL
(GR)
LG/N - 14
GN - 28
B-9
GR - 14
LH FRONT B - 9
GR - 14
LH REAR
B-9
HAZARD
SWITCH
BR - 14
(LG/N)
B-9
GR - 14
GR - 14
(GW)
SEE TEXT
green
RB - 14
GW - 14
HAZARD
B-9
GW - 14
green
P - 28
B-9
LH TS
INDICATOR
L
B
85
GN - 28
YP - 28
OD
SOLENOID
G - 14
G - 28
TRANSMISSION
INTERLOCK SWITCH
(Y)
(W)
REVERSE SWITCH
AND LIGHTS
CUTOUT SW
B
RH TS
INDICATOR
PN - 28
L
86
GW - 14
RH REAR
GW - 14
RH FRONT B - 9
B-9
HORN
PB - 9
(PB)
YN - 28
LG/R - 28
HORN BUTTON
BG - 9
PY - 28
TEMPERATURE
SWITCH
COOLING
FAN
FAN INDICATOR LAMP
PY - 28
HORNS
B-9
BB
- 28
B-9
LH
B - 28
RH
B - 28
COLOR CODES
N Brown
LG Light Green
G Green
U Blue
W White
B Black
R Red
Y
Yellow
K Pink
P Purple
S
Slate
O Orange
Wire colors shown in ( ) are supplied as part of
the component they are connected to.
= one pin of a multi pin connector. These
connectors may be used as is, or replaced with
bullet/sleeve or other connectors.
“TYPICAL” LATE CB
MGBGT WIRING KIT
5
material between the two pieces; otherwise, the terminals may
come into contact with one another, causing mis-operation of the
associated circuits.
crimp, so it will be necessary to strip both wires a bit longer, and
use both crimps to hold the bare wires.
Another helpful hint: when crimping around the
insulation on a small wire, it helps if you use a pair of diagonal
cutter to cut the ends of the crimp off, as shown on page 6, before
folding over the insulation. This just makes a neater job.
Snip off
Retaining clips
For small wires, snip off a portion of the crimp - it will make a
neater crimp this way.
Fuse block terminal/buss bar. At top is the standard
configuration, and below is a bar modified for this application
Wire Terminations: The techniques for terminating wires in the
fuse blocks, relay sockets, and flasher sockets are a bit different
than the normal practice for terminating wire connectors. The
flasher wiring is covered below, but techniques for the other two
are illustrated in the photo below.
If you do have the correct tool, as shown in the photo
below, making these terminations is very easy. This tool makes a
“factory” style termination, and is really quite good. See the
photo below for samples of wire terminations made with this
tool. You may have to look a bit to find one locally, but they can
be bought from some of the venders listed at the end of this
article.
“Factory” style crimping tool
Crimp the wiring/terminals using a pair of pliers. The lower
crimp should be over the insulation for a one-wire crimp, and
over the bare wires only for a two-wire crimp.
Standard crimping tools won’t work here, nor will
simply soldering the wires. If you don’t have the correct
crimping tool, it will be necessary to “crimp” the terminals onto
the wire using a small pair of pliers (duckbill pliers work best),
and then soldering them. Crimping alone isn’t adequate with the
pliers, so it is mandatory that you also solder. When terminating a
single wire, it is recommended that you use one of the crimps
around the wire, and the other crimp around the insulation (as
shown in the photo below). When you are terminating two wires,
you won’t be able to fit the insulation of both wires under the
6
A “factory” style crimp, using the tool shown above, and
described in the text.
After you have soldered or crimped the wires in place,
insert the terminals into the backs of the sockets firmly, pushing
until you hear them click in place. If you should insert one into
the wrong position, it can be removed using the same technique
outlined below for removing the flasher terminals, except the
retaining clips are in a slightly different position on the
terminals.
Flasher Sockets: When you receive your flasher sockets, they
will have 8” wire leads already attached. You can leave these
leads on and splice them into the remainder of the wiring if you
wish, but there’s a neater way.
crimping with this tool, make sure that the seam in the terminal is
on the concave side of the jaws, rather than on the convex side.
Otherwise, the tool will split the terminal, and make a very poor
crimp. I also recommend that you use non-insulated terminals,
solder them after crimping, and then slip heat shrink tubing over
the terminal.
Flasher socket, with a terminal which has been removed.
For a much neater installation, remove the terminals
from the flasher sockets and replace the wires with your own
wires, of the correct color code. To remove the terminals, use a
sharp pointed object (or, for an easier job, use two) to press on the
terminal retaining clips and pull the terminals out.When you
look at the sockets, it will be obvious how this is done..
After the terminals are removed, you will see how the
wires are soldered in place (quite sloppily, actually). Using your
soldering gun, unsolder the wires and remove them, shaking the
terminals while the solder is still hot to remove the excess solder.
Now, it’s a simple task to solder in your own wires. As an added
bonus, trouble shooting later on will be much easier if you have
the correct color coded wires.
Solder
GB crimping tool, from Lowes, Home depot, etc.
Bullet/Sleeve connectors: The only reason for using connectors
is to ease assembly - either on the factory assembly line or in your
garage. Connectors are also the most common place for
electrical problems, so you will be doing yourself a favor if you
eliminate as many as you can, wiring directly to the components
as much as possible. Still, there will be places where the standard
British bullet/sleeve connectors will be needed.
British Wiring supplies two different kinds of bullets those intended to be soldered, and those that may be soldered or
crimped. I recommend buying the latter type, and soldering
them, rather than buying the solder only type. They just work
better. When you solder, use a low temperature, rosin core,
solder, such as the 60/40 solder sold by Radio Shack. This is a
small diameter solder, and works very well for automobile
wiring purposes. Do not use acid core solder!
When soldering these bullets onto the wire, strip just
enough of the wire so that the insulation is just inside the bullet
when the tip of the wire is fully inserted. Hold the soldering gun
next to the bullet while you try to feed the solder into the hole in
the end of the bullet. As soon as the bullet is hot enough, the
solder will start to flow, and will be drawn up into the bullet. Feed
just enough solder to fill the bullet, but try not to feed enough that
Retaining
clips
Flasher socket terminal, as removed from a socket.
Crimping tools: Rather than using the typical auto parts store
crimping tool for the standard terminations, I recommend going
to Home Depot, Lowes, or similar, and buying a GB crimping
tool as shown above. This tool has the advantage that it crimps
“along” the wire, rather than “across the wire.” This spreads the
crimp over a larger area, and make a much better crimp. When
Proper technique for soldering bullet connectors
7
it wicks up the wire very far. A little bit of experimentation will
show you just how much solder to feed. See photo above.
There is another option for installing bullet connectors,
and that is to use a special crimping tool sold by British Wiring,
just for bullets. It’s a bit pricey, at around $50.00, but it is NICE!
I have one, and I will never solder bullets again.
sockets. Run the headlight wires directly into the headlight
buckets, cover the wires with protective sleeving as they pass
through holes in the buckets and the fenders to prevent abrasion,
and crimp AND solder the wires to the socket terminals. If you
should ever need to remove the wiring for some reason, you will
have to either cut the wires just short of the sockets and replace
the sockets when you’re finished, or remove the terminals from
the sockets as described earlier. Leave enough slack in the wires
to allow for this.
I believe I’ve covered everything you need to know to
build the Power block, and to install it in your car. Keep in mind
as you compare the cost of this panel with some of the
commercially available wiring systems, or to a stock
replacement harness, that the prices shown for this wiring
system is complete, and will replace ALL of the wiring in your
car. None of the other approaches will include, for example, the
inertia cutoff switch, nor will they have six relays. The cost for
this setup is very comparable to many of the aftermarket
systems, and cheaper than a stock replacement harness. If you
buy a replacement harness, you will still have to modify it to your
application. Just think how cool it’ll be to tell your friends “I
made my own wiring harness!”
Crimping tool for British type “bullet terminals.
HEADLIGHT WIRING:
For maximum headlight brightness, you should eliminate ALL
connections between the headlight relays and the headlight
OPTIONS:
8
85
G1
87 87
G
105A
G
G2
30
86
G
15A
POWER
RELAY
G
G3
G - 14/28
10A
R1
FUEL PUMP
R
INERTIA SW
10A
87
87
30
85
STARTER
WR - 28
86
WR - 14
YG - 9
STARTER
FROM
IGNITION
SWITCH
B-9
Y-9
Y-9
P
P4
N
85
15A
15A
P3
30
N
86
87
87
OVERDRIVE
P
P2
10A
15A
B-9
P1
OVERDRIVE
ON - OFF
SWITCH
86
85
DRIVING LIGHTS
LOW BEAMS
85
30
87
87
30
Y-9
B-9
TRANSMISSION
INTERLOCK
SWITCHES
YP - 28
OD SOLENOID
UP - 28
UP - 28
86
87
UP - 9
87
TURN SIGNAL
86
87
30
30
87
87 87 86
30
85
HORN
85
85
87 87 86
COOLING FAN
G
HIGH BEAMS
If you are using an older “A” type
overdrive unit, you will have to add a relay, as
the solenoid for this type OD unit draws too
much current for the selector switch to handle.
To do this, you’ll have to modify the circuit
and add a relay as shown to the right. Or, you
could eliminate the fuel pump relay, wiring it
directly to the fuse block, and rewire that relay
for the OD function. To add a relay for the OD,
just add the wiring shown in dark lines on the
right to the existing power block. The
mounting plate will have to be lengthened 1
7/32 to make room for the relay.
If you wish to add a relay for driving
lights, modify the circuit as shown, and as
described on page 2. If you are not using the
fuel pump relay for the OD circuit, you can
use it for the driving lights, wiring the pump
directly to the fuse block Even if you don’t
need to use the pump relay for another
function, you may not want to use it for the
pump either. In that case, just eliminate it as
shown.
Prefer to have a relay for the starter?
Wire it as shown, either adding a relay or
using one of relays that you might not be using
for it’s original function.
You may wish to locate the power
terminal to another location, off the panel, or
you may wish to eliminate it altogether and
wire the brown power leads directly to the
starter solenoid.
Many other options are open to you after all, this is a CUSTOM wiring system, so
design it that way YOU want it!
B
L
see text
HAZARD
L
B
P
DRIVING LIGHT
SWITCH
DRIVING LIGHTS
WG - 9
85
W - 28
W - 14
G - 14
N - 44
87 87
G - 14
10A
G - 14
G - 28
G - 28
86
30
15A
POWER
RELAY
G - 28
10A
N - 44
N - 28
N - 28
R - 14
N - 120
10A
N - 44
N - 28
POWER
TERMINAL
N - 28
BW - 9
85
P - 28
P - 28
P3
15A
P2
10A
P1
15A
RG - 14
30
86
87
87a
S - 14
15A
POWER
BLOCK™
NR - 14
FUEL PUMP
R - 14
YR - 28
P - 14
P - 28
P - 28
P - 14
BY - 9
86
30
87
87
B-9
85
30
87
87
86
P - 14 OR G - 14
SEE TEXT
85
COOLING FAN
LOW BEAMS
UR - 14
TURN SIGNAL
UW - 14
UW - 14
UR - 28
UR - 28
G - 14
LG/N - 14
HIGH BEAMS
B
85
30
30
87
87 87
SEE TEXT
85
HAZARD
P - 28
86
87
L
B
L
PN - 28
86
HORN
PB - 9
UW - 28
UW - 28
PY - 28
LG/R YN
28
28
BG - 9
BASIC POWER BLOCK WIRING
9
WIRE
Meters required per color per size
9
14 28
Color/size
Black
2
2
3
Black/Green
3
Black/Orange
1
Black/Red
1
Black/White
3
Black/Yellow
2
Blue
1
Blue/LG
2
Blue/Red
2
7
Blue/White
4
7
Brown
3
Brown/LG
2
Brown/Red
2
Brown/Yellow
3
Green
4
4
Green/Black
4
Green/Blue
3
Green/Brown
5
Green/Purple
5
Green/Red
7
Green/White
7
LG/Black
2
LG/Brown
2
LG.Red
2
Purple
4
2
Purple/Black
2
Purple/Brown
2
Purple/Green
1
Purple/Pink
1
Purple/White
4
Purple/Yellow
4
Red
6
Red/Black
1
Red/Green
2
Red/LG
2
Red/White
3
Slate
2
White
2
3
White/Black
2
4
White/Brown
1
White/Green
1
White/Purple
2
White/Red
3
Yellow/Brown
4
Yellow/Green
3
2
Yellow/Purple
1
1
Yellow/Red
4
Total cost for wiring:
Total cost for panel wiring only:
HARDWARE
44
1
120
Price
4.65
1.35
0.45
0.60
1.35
0.90
0.60
1.20
7.15
8.35
4
15.55
1.20
1.20
1.80
5.80
1.80
1.35
4.25
4.25
4.20
4.20
1.20
1.20
1.70
4.10
0.90
1.70
0.45
0.45
1.80
3.40
3.60
0.60
1.20
1.20
1.80
1.20
3.75
4.30
0.45
0.45
1.70
2.55
3.40
3.05
1.30
3.40
$123.05
$77.60
Note: Quantities shown should be more than adequate for a
“typical” application. For more precise values, depending on
where you locate the power block,you will need to measure
your specific installation before ordering. Wiring shown as
“shaded” is for the power block wiring, but the number of
meters shown in shaded areas may be for the entire system.
Total cost - panel only
Total cost - complete system
$153.66
$307.25
Part Name
Vendor
building supply
Mounting plate
Cable clamp - #16
building supply
Fuse blocks
auto parts store
Power terminal
MAD Enterprises
Flasher sockets
Ron Francis WW
Headlight sockets
American Autowire
American Autowire
Alternator plug
Alternator stud boot
American Autowire
Hazard switch DPDT
Waytek
Fan Switch SPST
Radio Shack/auto store
Fan indicator lamp
Radio Shack/auto store
Cutout switch SPST
Waytek
Fuel pump buzzer
Radio Shack
Hazard flasher
auto parts store
TS flasher
auto parts store
Waytek
Relay sockets
Relay socket terminals
Waytek
Relay (SPST)
Waytek
Relay (changeover)
Waytek
Wiper motor plug
British Wiring
British Wiring
Washer motor plug
Wire bullets (9 strd)
British Wiring
Wire bullets (14 strd)
British Wiring
Wire bullets (28 strd)
British Wiring
British Wiring
Sleeve, single
Sleeve, double
British Wiring
Inertia switch
Moss Motors
Total cost for hardware
Cost for panel mounted components only
Part #
n/a
n/a
n/a
CN-1
FC-32
500196
500201
500057
44263
your choice
your choice
44251
your choice
552
552
75280
31073
75102
75113
805
841
309
314
328
311
312
900-240
Quan
1
1
2
1
2
2
1
1
1
1
1
2
1
1
1
6
30
5
1
1
1
2
42
15
5
15
1
Price
7.95
0.50
4.98
4.99
9.00
3.00
3.00
2.50
5.00
5.00
5.00
2.53
5.95
2.95
2.95
0.73
0.10
3.60
3.38
3.00
1.60
0.12
0.12
0.12
0.30
0.50
49.95
Total
7.95
0.50
9.96
4.99
18.00
6.00
3.00
2.50
5.00
5.00
5.00
5.06
5.95
2.95
2.95
4.38
3.00
18.00
3.38
3.00
1.60
0.24
5.04
1.80
1.50
7.50
49.95
184.20
76.06
Items shown as “shaded” are panel mounted items. Depending on the year, additional multi-pin
connectors may be needed to connect the wiring to the steering column mounted switches. These
connectors are not listed here because you may prefer not to use them, and the type of connectors
varies from year to year, and one part number wouldn’t apply to all models. Check with the vendors
listed below if you wish to use them.
VENDORS
American Autowire Systems
150 Heller Place, #17 West
Bellmawr, NJ 08031
1-800-482-9473
www.americanautowire.com
Ron Francis Wire Works
167 Keystone Road
Chester, PA 19013
1-800-292-1940
www.wire-works.com
British Wiring
20449 Ithaca
Olympia Fields, IL 60461
1-708-481-9050
www.britishwiring.com
Moss Motors
PO Box 847
440 Rutherford Street
Goleta, CA 93116
1-800-667-7872
Waytek, Inc
PO Box 690
Chanhassen, MN 55317-0690
1-800-3282724
www.waytekwire.com
MAD Enterprises
PO Box 675
Springville, CA 93265
1-559-539-7127
www.madelectrical.com
NOTE: Miscellaneous small hardware items - screws, nuts, bolts, terminals, heat shrink tubing, tie wraps, harness
wrap, etc - are not listed. Prices shown are as of summer, 2002, and may not be current. Check with the venders for upto-date prices.
MATERIALS LIST
10
FUEL PUMP
POWER
30
30
85
87
COOLING FAN
86
85
87a
30
86
85
87
87
30
86
87
HIGH BEAMS
HORN
85
87
87
POWER
TERMINAL
30
30
86
85
87
86
87
85
87
NOTE: terminal designations are as viewed
from the back (wiring side) of the sockets.
87
86
87
“PURPLE” FUSE BLOCK
X
X
LOW BEAMS
“GREEN” FUSE BLOCK
L
L
HAZARD
FLASHER
TURN SIGNAL
FLASHER
Power Block Connection details - shown approximately 3/4 scale
8 3/8
1 7/32
1 7/32
1 7/32
1 7/32
1 7/32
1 1/4
3/16
4 1/2
UNIVERSAL
BRITISH CAR
POWER BLOCK
3/8
1/2
1/4 1/4
3/4
1
1
3 3/8
DRILL 13/64
17 PLACES
DRILL 1/4
4 PLACES
FOR 10-32
“NUTSERTS”
3/8
7/8
1/2
1
1/2
3/4
3 1/8
15/16
9 3/8
Power Block mounting plate - shown approximately 3/4 scale
11
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