GMC front parking light socket

[BigSix]

Is the front parking light socket on my 65 GMC a standard 1157? As nice as the original wiring is in my truck, the previous owner has done some interesting modification and wiring to the hood light harness and sockets. Just looking to replace the sockets with fresh new ones as they are rather tired. And also - those are not turn signal but just running lights - correct?

[jtrichard]

1157/1034 correct and both park and turn

[BigSix]

Originally Posted by jtrichard

1157/1034 correct and both park and turn

Thank you. I will have to rewire from firewall plug - at about 3 feet the previous owner started using wire nuts...

[BigSix]

In terms of wiring - any pics on that harness and grounding?

[ray_mcavoy]

Originally Posted by BigSix

I will have to rewire from firewall plug - at about 3 feet the previous owner started using wire nuts...

You might want to look into buying a replacement harness. This one is listed for 63-66 Chevy trucks --> http://www.americanautowire.com/shop...t-harness-3067 I think it would be the same for your GMC but I don't know for sure.

Originally Posted by BigSix

In terms of wiring - any pics on that harness and grounding?

This harness doesn't contain any ground wires. The sockets are grounded through the metal reflector/housings of the light assemblies. So make sure the holes that the sockets snap into are clean & free of corrosion. Also make sure the light housings are making good electrical contact with the hood since that's part of the ground path as well.

[BigSix]

So I'm getting zero current to the firewall connector where the harness plugs. Where does that connector draw power from - could I have unplugged it from the fuse box in any way? Headlights and tail lights work and horn is super weak but when I attached horn to battery it was strong. Could my issue be the horn relay?

[ray_mcavoy]

There are 3 wires/circuits in this harness & the section of the firewall connector it plugs into.

(1) The parking light circuit (purple wire on Chevy, not sure if GMC is the same) is fed directly off the headlight switch. This circuit will only be live with the headlight switch knob pulled out to the first detent. The parking lights in these years go back out again when you pull the knob all the way out to the headlights on position.

(2 & 3) The turn signal light circuits (light blue left, dark blue right) are fed directly off the turn signal switch. And the feeds to the front are separate from the rear since the rear turn signals use the same bulb filaments as the brake lights. Power into the switch is routed through the turn signal flasher.

Yes, bad contacts inside the horn relay could be preventing the horn from receiving full power and making it sound weak. Could also be a poor connection in the wiring between the relay & horn or in the feed wire leading to the horn relay.

[BigSix]

What is strange is that I cannot get any power out of the parking light/turn signal wires. Headlights work, dimmer switch works, but I cannot get parking lights or turn signals to work. Could my issue be in the steering column with the turn signals and that is also killing the parking lights?

[[JP]]

I've just been through all of this connecting my parking lights and turn signals as the previous owner ripped everything off.
I used a motorbike turn signal to test it out, which connector did what, not sure if yours looks the same as mine though

I followed the diagram and put a spade connector on the plug in the engine bay and got front turn signals working! (again using the bike light)
So on that photo, where the blade is connected turns the left turn signal on (flashing)
the one above turns the right turn signal on
and the one to the left of that blade connector turns them steady - parking lights, which is the first stop when pulling the lights switch, goes off once i pull another stop which turns headlights on



all i done was one wire to the blade connector, the other wire to ground

[BigSix]

Sorry what did you do to fix it? Thus far, using a test light, grounding to the block, I cannot get any of the 3 spaces on the firewall connector to turn on my test light. Somehow power is not making it to those 3 wires.

[ray_mcavoy]

Originally Posted by BigSix

Thus far, using a test light, grounding to the block, I cannot get any of the 3 spaces on the firewall connector to turn on my test light. Somehow power is not making it to those 3 wires.

For the parking lights, use your test light to check for power on the purple wire at the headlight switch connector.
Just in case it's a different color in your GMC vs. Chevy, the parking light wire should be the one leading to "terminal #7" in this diagram:



That diagram is for the later years that keep the parking lights on with the headlights so that terminal is missing from the switch pictured.

If you have power there, but not out at the firewall connector, check for a break somewhere in the purple wire between the headlight switch & firewall connector.

But if you don't have any power on that headlight switch terminal then you likely have a bad headlight switch or bad power feed to the switch. You mentioned that the headlights do work so I think you can rule out a bad power feed since the parking lights in these years operate off the same feed as the headlights.



Similarly, for the turn signals, use your test light to check for power on the light & dark blue wires on the turn signal switch connector near the steering column. If you have power at the switch, but not out at the firewall connector, check for broken damaged wires between the switch & firewall connector.

However, if there is no power on the light & dark blue wires directly at the turn signal switch, check for power on the purple wire. That's the feed from the turn signal flasher. If that doesn't have power, check the flasher & fuse. Note that the turn signal circuit is only powered with the key on.

[BigSix]

Thank you!