What are these wires for ? 72 GMC

[Canadian 72 C15]

Help
Can anyone identify what these wires and plugs would be for?

72 gMC with 307 and 4 speed floor shift.

It now has a 305 and is not using these anymore. They are all on the same harness passenger side are near the firewall.

One green wire on its own with a plug and loomed

One semi thick red (power I assume) with a plug

Then one 3 wire plug with a blue, green with a white stripe , and brown with a white stripe.

[LockDoc]

Originally Posted by Canadian 72 C15

Help
Can anyone identify what these wires and plugs would be for?

72 gMC with 307 and 4 speed floor shift.

It now has a 305 and is not using these anymore. They are all on the same harness passenger side are near the firewall.

One green wire on its own with a plug and loomed

One semi thick red (power I assume) with a plug

Then one 3 wire plug with a blue, green with a white stripe , and brown with a white stripe.

The Green one would be for the temp gauge sender (should be in the head by #1 spark plug)

The other ones look like Alternator wiring.

LockDoc

[Canadian 72 C15]

Originally Posted by LockDoc

The Green one would be for the temp gauge sender (should be in the head by #1 spark plug)

The other ones look like Alternator wiring.

LockDoc

Thanks for the response. I don’t know that the green one is long enough to reach over to the other side of the block by #1. I could try I guess. This would be the wire then I assume that goes to my temp gage in the dash ? Or at least did originally? I have a green wire on my thermostat housing now but again I don’t know if it’s hooked up anywhere else or it even does something.

As for the other plugs the red and the 3 wire plug yes a previous alternator connection sounds right.

[LockDoc]

Originally Posted by Canadian 72 C15

Thanks for the response. I don’t know that the green one is long enough to reach over to the other side of the block by #1. I could try I guess. This would be the wire then I assume that goes to my temp gage in the dash ? Or at least did originally? I have a green wire on my thermostat housing now but again I don’t know if it’s hooked up anywhere else or it even does something.

As for the other plugs the red and the 3 wire plug yes a previous alternator connection sounds right.

Yes, for the temp gauge. Some of the later engines may have had a sender in the T-stat housing but I think the '72 was still in the drivers side head. Not sure about the Canadian models though.

There is a port by the #8 plug also but you very seldom see a temp sender in that location. Do you have a temp sender in the drivers side head by #1 plug?

LockDoc

[Canadian 72 C15]

Originally Posted by LockDoc

Yes, for the temp gauge. Some of the later engines may have had a sender in the T-stat housing but I think the '72 was still in the drivers side head. Not sure about the Canadian models though.

There is a port by the #8 plug also but you very seldom see a temp sender in that location. Do you have a temp sender in the drivers side head by #1 plug?

LockDoc

I do yes but this is a 305 and the casting number says it’s from a 80-85 model year GM. But yes it does have a spade connector sensor there at #1

[kwmech]

Looks to me like an old NOx system wiring that cut out vacuum to the dist until you shifted into 4th gear. Used to be a solenoid bolted to the intake and a relay on the firewall. dark green wire does look like the temp wire with the insulation and the broken metal bracket. Looks like it may have been rerouted at some point

[Orange Crate]

Wow I just posted this link about 20 minutes ago for something else. You can look up the wire colors yourself here:


http://67-72chevytrucks.com/vboard/s...d.php?t=558016