trouble shooting opinions

[Ultrasummer]

Finally to the point where I can focus on trouble shoot some electrical gremlins. 1968 C10 stepside. 307 4 speed.

I'm getting ready to work on some electrical issues this weekend. Before I get to it, I thought I'd throw it out there and see if anyone had any opinions. Here's the problem. Turn signals don't work front or back. New tail lights only work on driver's side but not on passenger side. License plate light works fine. New rear wiring harness for new rear tail lights. No lights at all on passenger side rear.

I'm guessing a fuse might be the turn signal issue (that big silver guy in the corner of the fuse box). I can only figure it's a bad wire between fuse box and new rear wiring harness.

[Willys_MB]

It sounds like it might be a grounding issue. Check all the grounding points and clean them up and replace if necessary. It’s tedious, but that’s the most common issue on these trucks.

[Ultrasummer]

I will definitely be checking that out. Guess I'll start at the tail light and work backwards. Thanks

[Greasey Harley]

Originally Posted by Willys_MB

It sounds like it might be a grounding issue. Check all the grounding points and clean them up and replace if necessary. It’s tedious, but that’s the most common issue on these trucks.

^^^Agreed^^^^
Grounds, grounds. grounds
check/replace fuses
inspect and repair any molested wiring.
replace all the bulbs, clean and grease (di-electric grease)all the sockets.
Oh yeah and clean up every ground you can find.
Seriously, all of them. the whole truck.

[Ultrasummer]

I could see how it could be a grounding issue for the tail lights but if the turn signals don't work (front and back) .....are you guys thinking a bad fuse in the fuse panel?

[LockDoc]

-
Here is a good thread on grounding.

http://67-72chevytrucks.com/vboard/s...d.php?t=422234

LockDoc

[Ultrasummer]

thank you

[LockDoc]

-
And here is a good thread on turn signals.

http://67-72chevytrucks.com/vboard/s...d.php?t=712235

LockDoc

[rpmerf]

For troubleshooting lighting issues - Get or make a test light. Read the schematics. Follow the circuit end to end, finding where it stops working.

http://outintheshop.com/faq/wiring/w...s/image002.jpg
http://outintheshop.com/faq/wiring/w...s/image003.jpg

[special-K]

Do the 4-ways work? Did you try a new flasher?

[Andy4639]

My suggestion is start at the steering column and work your way back to the tail lights. Check the turn signal connection where the u shaped connector is. Then if it has power start looking at the new connector you installed. Check it with a test light with each light on and then with all of them on.
If you have a helper who can push the brakes and turn the lights on and off helps a bunch.

[CANUCIT]

I had the same problem and it was a grounding issue

figured it out after I bought 2 turn signal switches

[Ol Blue K20]

The big silver thing in the fuseblock is a flasher (there's 2). One for turn signal, the other for the emergency flashers.

[Sheepdip]

A quick inexpensive way to pin point a grounding issue is get you a 20" piece of light gauge wire with alligator clips on each end, one end to the Negetive battery post and the other end to your problem such as e.g. your tail light ground wire.

A small safety pin pushed thru the existing pigtail ground wire with the other alligator clip hooked to it will work. This is assuming your bulb sockets are in good contact condition and bulbs are good.

If it lights up/works you have a grounding issue, you can then proceed accordingly.

[PanelDeland]

On kind of the same topic but more about the tools for troubleshooting, I recently bought a "power probe". It's basically a meter test light and carries it' own power source. I'm still learning all it's uses but it seems a lot easier than trying to juggle three test tools at once (and finding/figure out which you want to use)
.

[HO455]

I recommend familiarizing yourself with the wiring diagram and where the components shown are on the truck. Remember that half of the circuit is not shown as it is the frame and body parts that make up the negative side of the circuit.

[Ultrasummer]

UPDATE:
Well I spent some time using all your advice. Here is the outcome: I put 5 new ground straps on with good bare metal.
engine to firewall
engine to frame
front inner fender to frame
cab to frame
bed to frame
Still had same problem. Traced it back to the tail light itself. Wiring all looks good. New LED tail light removed. With the power ON and associated turn signal on, I messed with the insertion point of the LED (much like the old bulb socket) and the light finally came on. Although it was in, it just wasn't making the right contact I guess. Lots of frustration but just ecstatic that that problem is solved and now on to the next thing. Thanks again

[LockDoc]

Originally Posted by Ultrasummer

UPDATE:
Well I spent some time using all your advice. Here is the outcome: I put 5 new ground straps on with good bare metal.
engine to firewall
engine to frame
front inner fender to frame
cab to frame
bed to frame
Still had same problem. Traced it back to the tail light itself. Wiring all looks good. New LED tail light removed. With the power ON and associated turn signal on, I messed with the insertion point of the LED (much like the old bulb socket) and the light finally came on. Although it was in, it just wasn't making the right contact I guess. Lots of frustration but just ecstatic that that problem is solved and now on to the next thing. Thanks again

Thanks for following up on this. Many people don't. It will help someone else down the road.

LockDoc

[53burb]

awesome! thx for the follow up also....many times that doesn't happen....

[Ultrasummer]

It's the least I could do. This will be a long and interesting journey with this good old truck. I'm sure you'll see me in the future asking many thought provoking questions. I look forward to the many years of knowledge and wisdom of you guys when I'm cussing like a sailor at this truck during the next glitch.
Thanks again.

[landarts]

Thanks for posting solution. I had the same issue and it came down to the screws that holds the rear tail light housing to the bed. The truck had a fresh paint job and the housing and screw was not making ground, once that was fixed the lights came on.

[HO455]

Good work! All those new ground straps will save you further heartache down the road. And as others have said "thanks for posting your results".