4x4Wire TrailTalk

Rear Turn Signals all flash?!

Posted By: hazard2600

Rear Turn Signals all flash?! - 09/14/13 06:21 PM

So I bought an 86 Chevy k20 Silverado 4x4. It had a 305 originally and was swapped out with a 454. When I purchased it, it needed a LOT of love and finally got it running smoothly. I now found that my turn signals don't work properly.
When I turn on the left or the right signal, both the left and right rear lights go on. The front works perfectly in both left and right and emergency signals (now that I replaced the blown bulbs.

I looked on all the forums and learned that I need to:
1) Make sure all the bulbs are the correct bulbs. (done)
2) Check Wiring. I'm not an electrical guru, but I did find that the dark green wire wasn't supplying any power to one of the rear passenger bulbs. I ran a replacement wire from the matching contact in the Direction/Switch panel attached to the firewall and got that bulb to light up. But they still ALL light up. I have checked the grounds and they all seem good as well.
Symptoms I have caught:
- Emergency lights work fine.
- Side marker and front lights work fine.
- Dash turn signal indicator lights work fine.
- If I hit the brakes when the emergency or turn signal lights are one, all signals go on and the indicator lights also stay on.

The only issue I have found (and I don't know if it is an issue) is the brown wire coming off the Direction/Switch panel has no power. I'm not sure if it should or not.

I am totally stumped. Any help would be MASSIVELY appreciated. <img src="/forums/images/graemlins/confused.gif" alt="" />
Posted By: 4x4Wire

Re: Rear Turn Signals all flash?! - 09/15/13 07:53 PM

Do you have wiring diagrams for the stock (305) setup and the transplant (454)???

Somewhere in that swap, you may have a different wiring configuration in a plug.

I have seen turn signal issues when trailer towing connections have been spliced into the wires. Also, check the flasher units. Some vehicles have dual flashers - one for turn signal and one for emergency blinkers.

Don't assume ground connections are good....
Posted By: hazard2600

Re: Rear Turn Signals all flash?! - 09/16/13 03:03 AM

That's a good point about the tow wiring. Someone DID splice in to the lights for a tow connection, then cut it off and covered it in electrical tape. I need to inspect it closer.

I did find the chassis ground on the passenger rear turn signal was non-existant. So I cut all the ground wires on both signals, spliced them together, and reconnected them to a clean ground on the chassis. I hope that didn't screw anything up! lol
Posted By: hazard2600

Re: Rear Turn Signals all flash?! - 03/10/14 07:19 PM

Sorry for resurecting a very old post, but figured it'd be best to include all the previous chatter.

After much deliberation and inspection and hunting, I cannot find any bad grounds in my turn signal electrical wiring whatsoever.

I had a thought the other night. Since my front turn signals work perfectly, Could I just piggyback the current from the front turn signals and run it to the corresponding rear signal? If I just slightly increase the fuse to handle the additional load, maybe it would be bright enough to work? It already seems to have enough grounds on the entire circuit to handle a speaker capacitor. Why not a couple additional bulbs?

I know it sounds hokey and I am a strong proponent of "Do it right the first time", but I really have no other options going for me.
Posted By: rxinhed

Re: Rear Turn Signals all flash?! - 03/14/14 04:36 AM

First question for you, do you have brake lights?

Second question, have you checked the wires on the combo switch / steering column / rear loom?

Bad idea to jump off a separate circuit and increase the load. This will lead to an overloaded ciruit, hot wires, and potential fire. If you have to use the vehicle, I'd suggest a new loom from the cab back.
Posted By: 4x4Wire

Re: Rear Turn Signals all flash?! - 03/19/14 03:16 PM

One thing to try...

Splice in a wire from front to back to see if you can trigger the rear turn signals. You MAY have a broken wire in the wiring loom.
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