Where Do These Wires Go

[roadking77]

Trying to figure the wiring out on my 400/4 speed. I have the laminated diagram but I cannot make heads nor tails of it compared to what I have. Enclosed are the few wires that I believe are for the motor itself. I have the front harness identified with the lights horns etc. and I think there is a separate harness for the ac/heater stuff. Its the wires to the motor itself that I am working on. I am including pics of the wires I have folded in half showing the wire itself and the connector at the end.
2023-11-02_05-07-27 by Kerry Grubb, on Flickr
#1- green wire with the end connector2023-11-02_05-07-21 by Kerry Grubb, on Flickr
#2-Red wire with end connector- fairly heavy gauge compared to the rest

2023-11-02_05-07-15 by Kerry Grubb, on Flickr
#3-Red wire (heavier gauge) and red wire with black stripe (thinner gauge) connected to the same terminal at the end.

2023-11-02_05-07-06 by Kerry Grubb, on Flickr2023-11-02_05-06-55 by Kerry Grubb, on Flickr

#4-Blue wire heavier gauge cut end
#5-Blue wire smaller gauge cut end
2023-11-02_05-06-49 by Kerry Grubb, on Flickr
#6-pinkish wire heavier gauge with connector
2023-11-02_05-08-02 by Kerry Grubb, on Flickr
This is the terminal block at the fire wall. My question is 'how do the wires attach at this point?' Is is easy enough to pull one out an replace. The entire thing looks kinda nasty, and I assume the heavy tar like substance is some sort of sealant? Dont know if there are numbers underneath all of the mess that identifies with the chart that I have.

[5th T/A]

Kerry, This is not going to be an easy one to answer. Hopefully someone can give better advice than me.

I had the luxury of labeling all my wires on disassembly taking all the guess work out of what goes where when going back together. It would be great if you can get assistance from someone close by who has good electrical trouble shooting ability.

The bolt in the center of the bulkhead connector will release it and the connectors kind of slides together to make one large connector. I would think there are numbers on the connector that you can correlate to your wiring diagram, but really don't know. There is a group of about three wires that comes from the alternator and some are spliced into a fusible link. The heaviest gage wire connects to stud on the back of the alternator. There is a two-wire connector that plugs into the alternator Other than the starter motor this is what provides power to everything in the car. If this wiring is in poor shape, you could have some flaky problems. If the insulation is hard or cracked this could short out and you would lose power to everything.

You might want to consider replacing the engine wiring harness, it should be available from multiple sources. If the wires are labeled it will be easier to figure out what the wires connect to.
I don't know if the plastic bulkhead connector is part of the harness or not. This is where it would be great to talk to someone who has already replaced the harness.

The second photo from the top shows how the bulkhead connector comes apart. http://www.firebirdtransamparts.com/techinfo/harness/harness.htm


Sorry I can't be of more help.

[Wallington]

Yes. the goop is just to seal the block from moisture getting in or through. That centre bolt holds the lot in place. The plug is clipped together of two parts, one for engine and one for headlight. Easy to unplug for a look, you can get the foam seals now too that go on the inside of the blocks when connected.

What wiring diagram are you using, a generic version? I have several, and many for 78 which would be almost the same for a lot. But yes, your pics show various engine water temp sender, oil pressure, alternator and HEI wires. A/C also uses the engine harness to connect from.

[Wallington]

Here's the 400 engine section of the 78 diagram.

Firebird 1978 Electrical diagram 2 of 5 by Ben, on Flickr

[wheels78ta]

I have a 400/4 speed.......I also bought a new harness plus kept the old one.

The green wire is for the water temp sender

The only blue wire that I have is for the oil sending unit.

 

[roadking77]

Thanks for the help and the pics and diagrams. The existing wires are shot to say the least. I did not want to start yanking stuff until I knew if I could get the new ones in easy enough. I had considered a new harness but the cost was pretty high compared to that of buying a few pieces of wire. I may just bite the bullet and get one assuming the connectors are all there. The bulkhead connector is what had me scared.

Walli... That diagram is a bit better than the one I have. I bought a laminated copy, it is pretty good but again the connections at the bulkhead are confusing. I cannot get my head wrapped around the orientation of it?