Engine wiring harness help

[nicholasmansfield]

Have a couple wires left that I’m not certain of where they go. I imagine purple and yellow are heading towards the starter. 69 with Hei. Does anyone I’ve an engine wiring harness diagram or any thoughts? Thanks in advance.
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[RustyPile]

Go to the electrical forum on this site. The first thread is a "sticky" that lists many, many electrical wiring diagrams for our trucks.
http://67-72chevytrucks.com/vboard/f...splay.php?f=64

[HO455]

Here a link to the schematics.

http://67-72chevytrucks.com/vboard/s...d.php?t=185856

Just shooting from the hip I believe the upper single green in the photo is the temperature guage sender. The double connector green is either the turn signal or the marker light. And the yellow one to the coil and maybe the blue one with it is the oil pressure switch???
Is the harness for guages or idiot lights?

You're correct about the purple and yellow ones.

[RichardJ]

DO NOT connect the yellow wire to the R terminal on the Solenoid.

The R terminal has that little bent finger attached to it inside the solenoid cap. The solenoid has two inductor coils. When voltage is REMOVED from an inductor, it can generate a very high voltage spike. If that finger is bent a little out of shape and touches anything when the solenoid is released, it can send that voltage spike up that yellow wire to the HEI and destroy the module.
That washer isn't held very tight and usually flops around a little bit.

A voltage spike on that yellow wire up to the original points ignition would go completely unnoticed.

If you look at many AC compressors since 1980, you'll find most have a diode across the compressor clutch coil. The clutch coil is an inductor that can sent a voltage spike back to the AC controller when the AC clutch cycles off.

I'm not going to go into how you wire your HEI, because I usually won't agree with how most people will tell you how to do that.
If you leave that yellow wire in the harness, fold it back on itself and tape it up.

[zosoppp]

The double green wire harness might be for a manual trans with floor shifter (reverse switch on trans itself, not on the column).

[Jason Banks]

That engine harness must have been from a truck with a 4 speed. The green light green go to the switch on the 4 speed trans. I think it's backup light switch.

[Johnl48]

I believe the green wires go to transmission for backup lights

[LockDoc]

Originally Posted by nicholasmansfield

Have a couple wires left that I’m not certain of where they go. I imagine purple and yellow are heading towards the starter. 69 with Hei. Does anyone I’ve an engine wiring harness diagram or any thoughts? Thanks in advance.
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The Green one with the bracket is the temp sender wire as HO455 said.

The wire runs along the valve cover/intake manifold and there should be 2 small clips for it on the valve cover. It runs down over the front of the head and the bracket fastens to the bottom water pump mounting bolt, then the wire goes under the #1 spark plug and back up to the temp sender. This is to keep it away from the exhaust manifold..... The bolt in the water pump is a special bolt that has a stud on the head so the bracket can be secured to it. The cloth type sheath over the wire is to protect it from chaffing and heat. I will see if I can find a picture.


EDIT: Here are some pictures. I think a couple of them were posted by "FirstOwner69".

LockDoc
.

[nicholasmansfield]

Originally Posted by zosoppp

The double green wire harness might be for a manual trans with floor shifter (reverse switch on trans itself, not on the column).

I have a 3 on the tree. Will my backup lights still work without that being able to plug in anywhere?
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[nicholasmansfield]

I realized that I had the wrong harness. I swapped to one with an Hei connection. Now I’ve just got the yellow next to my purple starter wire which I believe doesn’t need to be used with the Hei left. The double green which it sounds like is my backup lights, but I have 3 on the tree so they won’t go anywhere? I also have the blue wire with the plug left that I think might be to the oil pressure switch which I don’t think I would have either, I have a hard line going into my gauge cluster for oil pressure. If this is correct l, do I just make sure these wires are just out of the way?
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[zosoppp]

For the TotT shifters, the reverse switch is on the column inside the cab. So the Green/Dk Green wires don't go through the main bulkhead connnector but go directly to said switch.

The reverse switch is roughly where a neutral safety switch would be on an automatic column but with a different style two pin connector.

[nicholasmansfield]

Originally Posted by zosoppp

For the TotT shifters, the reverse switch is on the column inside the cab. So the Green/Dk Green wires don't go through the main bulkhead connnector but go directly to said switch.

The reverse switch is roughly where a neutral safety switch would be on an
automatic column but with a different style two pin connector.

Anyway I could see how that’s ran?
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[HO455]

This thread may help.

http://67-72chevytrucks.com/vboard/s...d.php?t=794727