I need help with to problems

[Mikeymike383]

1st what is this wire. my truck is a 73 with mech oil pressure gauge so I'm not sure if thts what it's 4.
2nd when I got my truck it had no gauges. I have a rlly good friend that only sells 73-87 truck parts and he gave me gauges out of a 74. it has the dummy seat belt light and brake light. so the brake light stays on until I turn the truck off. seat belt light is always on even after I take out key

[blazer74]

I also have that connector on my 74. Forget if it's battery hot or ignition hot.
Accessory not used I would  assume.
Never looked at a wire diagram or thought about it much.
Could be for a throttle kicker or timed spark control, really don't know.

[blazer74]

Does that cluster have a voltmeter or an amp gauge?

Noticed the temp gauge is pegged also

[Mikeymike383]

I want 2 say amp. but the guy b4 me cut all connections on engine side. so I'm trying 2 find stock connectors

[blazer74]

The reason I ask is 73-75 had amp gauges, 76 + had volt meters and the are wired different meaning burn/smoke/melt

[Greybeard]

You HAVE to match the gauges with the circuit board. IF you don't, things don't work right all the time. I have a 75 electrical repair manual around here somewhere, the problem is finding it. I have piles of manuals from everything I have ever owned. 

[Greybeard]

OK found the wiring diagram for the 75, should be close enough.

This would be the wires through the bulkhead connector...


This part is for the circuit board connections...


And this is an overall...



They might not be much help unless you can get it to expand clearly. If you can figure out where I might take a close-up I'll be happy to.

[blazer74]

The connector in question near the booster is a tan wire under the gunk. Wire # 20T141B     Ties into the TCS/Radio fuse.


TCS.  Trans controlled spark (optional)


That's According to my 74 wire manual

[Greybeard]

On the pages of the 75 wire diagram that wire color and number is for different engines available that year but regardless it was used for the idle stop solenoid. Not used with an automatic trans.

So, it's always good to have choices 

[blazer74]

Yep the idle stop power comes from the same place if used. Wire 141 has diff variables.