Wiring Diagram For 1948 Ford Truck
I made a written tabulation (second item below) of OE wiring colors to use with my '47.
TABULATION OF WIRE CIRCUITS, COLORS AND GAUGES
FORD CARS BETWEEN 1941 AND 1948
Mercury cars similar; Lincoln cars and Truck systems may be similar but often vary.
This tabulation was transcribed December 2015 from the following sources:
(1)"Ford V-8 Service Bulletins; 1941-1948 Complete; Publication Pages 267-268; 1945-1947;Subject No. 15999; Wiring; Bulletin Page No. 168; Published May 17, 1947"
(2)"Ford 1942-1948 Shop Manual – Service Handbook; (Appendix) Service Bulletin; Unnumbered Page titled "Wiring Diagram of DeLuxe and Super DeLuxe Ford V-8, 1945-48"
(3) 1941-48 Ford Book by The Early Ford V-8 Club of America; Copyright 2004; Appendix C; Pages C-5, C-7, C-8 and C-9 (wiring diagrams, color code diagrams, etc)
(4) "Service Manual" Ford …. 1946 thru 1948 (reprint); Copyright 1946 Ford Motor Company; Containing Part One, Part Two and Part Three with Chapters I thru IX.
Within the above four references (a) some contradictory information was found regarding wire colors and gauges; (b) descriptions of wire color combinations were found to vary i.e. the terms "tracer" and "cross tracer"; (c) common modifications are noted in italicized text.
IMPORTANT: Circuit wire colors and gauges are based on original 6 volt systems as described in the above publications. Check your system and equipment to determine if there were later changes.
**CHANGES: If converting to a 12 volt system, OE 6 volt wiring is adequate only if in top condition, due to voltage change .... BUT certain modifications must be made or are recommended: i.e. starter motor, generating device, light bulbs, voltage reducers added to fuel, oil and temp gauges, elec clock, radio and heater motor (last three were OE options). Six volt starter solenoid, horns and horn relay
maysurvive but should be altered/replaced. Consider sending some items to professionals for conversion i.e. starter, generator, clock, radio, heater motor.
**CAUTION: Based on OE wiring diagrams the Ignition and Cigar Lighter Circuits are connected to the "input terminal"of the Circuit Breaker and thus are unprotected/unfused. Fuses should be added to protect them. Other than the horns, other OE circuits are protected by the original Circuit Breaker. [I did add a fuse on the horn circuit] Personal experience: The insulation on the feed wire to my ignition switch melted due to overload by key-operated accessories. I corrected this by running a feeder wire from the ignition switch to a 30 amp relay under the dash, which turns-on a small fuse board. The new fuse board, fed directly by raw battery power, now feeds the key-operated accessories i.e. heater, radio, directionals, wipers, etc. Low power items such as dash gauges, tach or ignition resistor (if you have either) remain directly operated from the ignition switch.
CIRCUIT DESCRIPTIONS ORIGINAL COLOR AND GAGE
Generator to Regulator:
Generator Armature to "A" regulator post Yellow with Black 10
Generator Field to "F" regulator post Black with White 16
Generator "B" post to Circuit Breaker Input Yellow 10
Generator Ground to Regulator Ground Black with Red 16
Alternator if used (3-wire) output to starter relay Yellow 10
Alternator Field to ignition switch Brown (varies) 16 (with a 10 ohm 10 watt resistor & 5 amp fuse)
Alternator Sensor to starter relay White 16
Circuit Breaker Input to Charge Indicator; Yellow 10
Charge Indicator to Starter Relay; Yellow 10
Starter Relay from Starter Button. Black 16
Starter Relay to Horn Relay; Yellow with Green 10
Horn Relay to Horn Button; Blue with Yellow 14
Horn Relay to Horns. Yellow with Green 14
(also found as Yellow with Black)
Circuit Breaker Input to Cigar Lighter. Yellow with Green 12
Circuit Breaker Input to Ignition Switch. Yellow with Black 14
Ignition Switch to Fuel Gage; Black with Green 16
Fuel Gage to Temp Gage; Black and Green 16
Temp Gage to Sender Unit(s). Black 16
Fuel Gage to Tank Sender Unit. Yellow 14 or 16
Ignition Switch to Coil Resistor; Black with Red 16
(also found as Red with Blue)
Coil Resistor to Ignition Coil; Red and yellow 16
Ignition Coil to Distributor Points. Black 16
Ignition Switch to Oil Gage; Black and Yellow 16
Oil Gauge to Pressure Sender Unit. Black and Yellow 16
Ignition Switch to Optional Heater. (unknown) 12 rec
CB Terminal "A" to Stop Lamp Switch; Green 14
Stop Lamp Switch > Stop Lamps Green 14
CB Terminal "A" to Pillar Lt Switch > Lamps Black with Blue 16
Pillar Lt circuit to Electric Clock Fuse Yellow with Black 16
CB Terminal "A" to Dash Lt Switch; Yellow with Red 12
Dash Lt Switch to Instrument Lt Rheostat; Black with Blue 16
Rheostat to Instrument & Clock Lts. Blue with Red 16
Dash Lt Switch to Tail Lamps; Black 14
Tail Lamp circuit to License and Trunk. Green 14
Dash Lt Switch to Parking and Ignition Lock Lts. Black and Yellow 16
CB Terminal "H" to Dash Light Switch; Red with Yellow 12
(also found as Yellow with Red)
Dash Lt Switch to Floor Foot Switch; Yellow with Black 16
(also found as Black with Yellow)
Floor Foot Switch to High-Beam Lts; Green with Black 14
(also found as Black with Green)
Floor Foot Switch to High-Beam Ind. Lt; Green with White 16
Floor Foot Switch to Right Low-Beam; Red with Black 16
Floor Foot Switch to Left Low-Beam. Red with Yellow 16
(also found as Black with Red)
**Accessories NOT covered in this tabulation: (1) Radios; (2) Fog Lights - circuit Breaker Input terminal to 20 amp fuse; #14 wire; color optional; (3) Directional Indicator System; (4) Tach; (5) Electric radiator fan; (6) Aftermarket elec wiper motor; (7) Overdrive or Columbia rear end [my BW R10 OD works fine with 30 amp fuse & relay and #10 wire to its solenoid]. Aftermarket providers often provide wire, fuses and hopefully instructions.
REVISIONS: ** indicates a paragraph edited/amended by drb on 2/26/2017.
Note: The first item I attached below is from a Dealer's Service Bulletin and is similar to V8Coopman's diagram.
Posted by: jeanny-lee02.blogspot.com
Source: https://www.fordbarn.com/forum/showthread.php?t=215538