Need wire identification for 78 Fj40 (1 Viewer)

[matzell]

I am having trouble figuring out where these wires go. They come out of the harness at the back of the t-case. I know the light blue and red tracer goes to the back up light switch. (LR). What I need to figure out is what do the two light blue (L) go to?

Thanks in advance

 

[Living in the Past]

78 has a forth gear sensor on top of the transmission that is a single wire.

 

[matzell]

I also have a single black wire with a green connector on it? Could that be the black one? The chassis is a 77, harness is a 78. I do not know what the trans and t-case came out of. This was a v-8 conversion that I am putting back to a 78 2f 4spd truck.
Thanks

 

[BeerM3]

This shows a blue with red tracer wire coming to the reverse light switch, and two spliced red with blue tracers leaving it. The first one matches your b/r wire. Maybe the other two are to your reverse lights and the color diagram is off? Wouldn't be the first time. You could pop the tail lens and jumper one of those to check.

Is your rear heater in place / functioning?

 

[matzell]

Rear heater runs up the heater hoses and plugs in under dash. I have studied the diagram and can not seem to find anything that those wires go to????

thanks,
Rob

 

[Living in the Past]

Do you have the wire going to the driver's side seat belt?

 

[BeerM3]

Rear heater runs up the heater hoses and plugs in under dash.

Same with mine which is a '76, but your wire colors looked to be a match with those. I wasn't sure if they routed them from underneath on a '78 which I believe has 2 fan speeds but sounds like they didn't. Could be the seatbelt buzzer?

If it hasn't been retrofitted over the years, can you look at the wire colors coming into your taillights and verify if you have that same light blue wire there too? It would make sense that the 3 are bundled together on their way to/from the reverse switch on top of the trans, and someone just cut them below where the splice was for the wires that branch between the l/r reverse lights and the switch.

I know I and others have found small discrepancies between the color codes shown on Haynes or other aftermarket diagrams and what's in the actual harness. Not many, but a few. Have you checked the pdfs at Coolerman's website? Blue is typically associated with the heater, but that's not to say someone didn't "redo" your rear harness after snagging it on a branch out wheeling back in the 80's? If you don't have it already some FSM's are posted on, I believe, Trollhole's website. You can search for it in the classifieds. Look for "hell of a price".

 

[Coolerman]

Prepare to be confused: Starting in 1978 Toyota, for whatever reason, started using some solid colored wires in the rear chassis harness instead of striped wires.

An example is the two light blue wires you show. Those are actually going to the reverse lights. Those two wires BOTH go to a single female bullet connector. The Blue/Red wire you show should also be a female bullet connector. The two wires from your reverse switch will connect to the Blue/Red wire and the two blue wires. When the switch is made, +12V from the Blue/Red wire will go to both the blue wires lighting the reverse lamps.

FYI
Blue/Yellow is for the 4th gear indicator if so equipped
Green is for the seat belt if so equipped AND for Park/Tail
Yellow is for Right Turn (Normally this wire is Green/Yellow)
White is for Brake Lights (Normally this wire is Green/White)
Red is for Left Turn (Normally this wire is Green/Black or Green/Orange)
Blue is for Reverse Lights (Normally this wire si Red/Blue)

Mark aka Coolerman

 

[BeerM3]

Those are actually going to the reverse lights.

lol...I got one right! Blind squirrels and all that...