Need help with my front park lamps/turn signals. I have a 1966 1001 GMC.

[esquibdl]

Hello, I need help from this group. I have been chasing electrical and ground problems on my 1966 1001 Stepside GMC pickup. I finally got my rear taillamp/turnsignals/brake lights working by determining that there was not a good connection between the frame and chassis where the taillight assemblies mount.
Now my attention is on the front park lamp/turn signals which are not working.
Question: Where/how do the front park lamp turn signals get their ground from?
Also, I have noticed that the dome light inside the cab will not come on either.

One more thing I just noticed is that when I turn on the ignition switch to start the truck my rear taillight/turn signals stop working while the truck is running. They work perfectly fine in the AC mode of the ignition switch but not after I start the truck.

All four head lights work in both Hi-beam and Lo-beam even with the truck running.

Need help chasing these electrical gremlins.

Anybody that wants to help me via email may contact me at my personal email:

Thank you

DAVID L. ESQUIBEL
email: EsquibDL@comcast.net

[FetchMeAPepsi]

If you're not getting rear lights after starting the truck, you didnt fix it. You should have lights all the time when the key is on. How did you "fix" the rear light grounding issue? Any pictures?

[James]

First thing you should have is a wiring manual for your truck, before any electrical troubleshooting can be performed.

Originally Posted by esquibdl

Now my attention is on the front park lamp/turn signals which are not working.
Question: Where/how do the front park lamp turn signals get their ground from?

The front will ground at the lights. If the hood is not grounded to the frame it won't turn on.

Originally Posted by esquibdl

Also, I have noticed that the dome light inside the cab will not come on either.

Check your fuses, it should be label Tail/Stop/Dome. Dome light come on when the headlight knob is turn full bright. There should be a detent in the switch when it turn on. For it to operate by the doors a switch will need to be added to both door frames between the hinges.

Originally Posted by esquibdl

One more thing I just noticed is that when I turn on the ignition switch to start the truck my rear taillight/turn signals stop working while the truck is running. They work perfectly fine in the AC mode of the ignition switch but not after I start the truck.

This sound more like a bad ignition switch. It should operate in run and ACC position.

[AZKen]

Email sent

[esquibdl]

I used a ground strap and bolted it between the frame and the rear chassis where the turn signal/tail lights get mounted.

[esquibdl]

Got all external lights working. Headlights work - both lo-beam and hi-beam, park lamp/front turn signals work. Tail lamp/turn signal/brake lights work. Turned out to be bad grounds in the front between hood and battery/chassis ground. In the back, bad ground between truck frame and truck box where tail lights mount.

Still can't get the dome light to work. Bulb checks good, dome housing has power on one side of the bulb, and I can bypass the light switch across the bulb by jumping that side to ground and see that the bulb lights up. Any ideas here? The rest of the light switch is working fine, just the dome light is not coming on with the switch.

[esquibdl]

Got all external lights working. Headlights work - both lo-beam and hi-beam, park lamp/front turn signals work. Tail lamp/turn signal/brake lights work. Turned out to be bad grounds in the front between hood and battery/chassis ground. In the back, bad ground between truck frame and truck box where tail lights mount.

Still can't get the dome light to work. Bulb checks good, dome housing has power on one side of the bulb, and I can bypass the light switch across the bulb by jumping that side to ground and see that the bulb lights up. Any ideas here? The rest of the light switch is working fine, just the dome light is not coming on with the switch.

[James]

Originally Posted by esquibdl

Still can't get the dome light to work. Bulb checks good, dome housing has power on one side of the bulb, and I can bypass the light switch across the bulb by jumping that side to ground and see that the bulb lights up. Any ideas here? The rest of the light switch is working fine, just the dome light is not coming on with the switch.

Have you tried grounding the dome light wire at the headlight switch? This will make sure if the wire not broken, if the light comes on then the wire is good. Then the problem would be at the light switch. The switch body needs to have a good ground. If there any paint or rust on either side of the switch mounting hole our on the switch body where it make contact with the dash will need to be clean. While you have the switch out make sure the switch has a good continuity (with the switch in the on position), from the male spade terminal to the switch body.

Hope this help.
James

[esquibdl]

That is an excellent idea. How do I locate the dome light wire at the head light switch. Does anybody have a pinout of the 66 GMC headlight switch? It would be nice to know where the dome light plugs into the headlight switch for power and ground connections.

I have removed the head light switch from the dash mounting hole and it is now just dangling there, does that mean that it no longer has a good ground connection? Since I have removed it from the chassis ground?

[James]

Originally Posted by esquibdl

That is an excellent idea. How do I locate the dome light wire at the head light switch. Does anybody have a pinout of the 66 GMC headlight switch? It would be nice to know where the dome light plugs into the headlight switch for power and ground connections.

I have removed the head light switch from the dash mounting hole and it is now just dangling there, does that mean that it no longer has a good ground connection? Since I have removed it from the chassis ground?

I do not have a 66 Manual. However on my 1964 manual the color of the wire is natural (what ever that means). Another way to know the color of the wire is, the wire from the dome light all the way to the headlight switch is a single color. So look at the dome light, you already know which side is hot, look at the ground side for the color of the wire and it will be the same at the switch.

Once the switch is removed from the dash there is no ground available. If you have a jumper lead, you can connect one end to the switch and the other end to a known good ground. Then operate the switch to the dome light position and it should come on.