C3 1974 Starter Wiring

[Richard M.]

I'm helping an acquaintance at his house on a '74 project, manual transmission. Lots of wiring issues.

At the starter harness on the car, I see a #16(?) black wire with no terminal. I have to trace it back, but could this be the lead going back to the ammeter? I see on the diagram below, it shows (at the ammeter), the wire starts as black, then becomes red, then brown fusible link, then red at the starter battery terminal on the solenoid.

1974 Wiring Diagram

What is the gauge of the RED wire feeding the ammeter? I would think it should be a #10 or #12. This black wire in question is only a #16 so I'm unsure what's going on. What is the fusible link rating?

Rich

[Joseph K.]

Re: C3 1974 Starter Wiring

On my 69 there is a back 16 ga wire that comes down with the starter wires that is a ground. The wire leaves the starter wire bundle about a foot or so from the starter.

Joe

[Larry M.]

Re: C3 1974 Starter Wiring

I'm making a wild guess, as I don't have a '74, but IIRC, for at least a portion of the model year, GM vehicles had a seat belt interlock relay, or some such terminology, that prevented the starter from engaging unless the driver's seat belt was buckled. Also, IIRC, there was some sort of override button for this function that was mounted on the firewall.
If, way back when, I had a '74 GM product with such a restriction, there's a very good chance I would have rendered it inoperative by whatever wire-cutting/splicing means necessary.
Is it possible you've encountered such a modification made by a prior owner, and perhaps all the original components are no longer in place, leaving wires with no place to go?
Larry

[Richard M.]

Re: C3 1974 Starter Wiring

I was thinking a ground also, but nothing in the wiring diagram showing that. I suppose it could be a seatbelt related circuit also. Either way I have to get back to the car to diagnose more. I recall I could not see a heavy gauge RED wire anywhere.

Thanks,
Rich

[Ed D.]

Re: C3 1974 Starter Wiring

There a several small black wires in the wire harnesses, almost all are ground wires of some sort. The one you are refering to could be the the wire to the tcs switch on the trans. If you have many more wiring quesintions, I would recommend getting the service manual with the wire diagrams.
Ed

[Richard M.]

Re: C3 1974 Starter Wiring

Yes I have the service manual. It has no helpful information. It has no physical layout of the harness to the starter. The wiring diagram in the link in my first post is the correct wiring diagram for 1974. As you can see it has no gauges shown on the color codes, all it shows is a thicker bold line for the heavier wires, and shows no ground wire at the starter. It is likely incomplete.

Unfortunately the diagrams show electrical only circuits, not any physical harness descriptions. Many times the ground wires in a harness are shown far away in an electrical wiring diagram. IMO this has always been a common flaw in automotive wiring diagrams.

Rich

[Rich W.]

Re: C3 1974 Starter Wiring

This may help or not..but this pic is of my 73 in the garage..its a stick also..the one black wire is loop ended and grounded..http://i1216.photobucket.com/albums/...ket_35003_.jpg

[Richard M.]

Re: C3 1974 Starter Wiring

Rich, That helps alot. It makes perfect sense now that I see in the photo it's attached to the bellhousing bolt. The wire on this one wouldn't reach the starter bolt, where the ground normally attaches on most midyears.

Thanks much......Rich

[Rich W.]

Re: C3 1974 Starter Wiring

I think that wire does something with the wiper motor..not sure..but a friend of mine put a clutch in his 71 and he hooked up that wire onto the starter solenoid..it melted a bunch of stuff up on the firewall..glad this pic helped..

[Richard M.]

Re: C3 1974 Starter Wiring

So looking at the diagram above again a little closer, I think it's the ground for the heater blower AND the wiper motor. If you look at the diagram, the ground for the blower is just a simple ground symbol right next to the symbol for the blower.

As I mentioned, these diagrams never tell you the exact ground connection for the wire, just a symbol to ground.

I would imagine the '74 AIM may show this ground wire in the appropriate body wiring section. If anyone can snapshot a photo of that in the AIM I'd appreciate it.

Thanks,
Rich