Paging all [automotive] electrical gurus

[Hawkmoon]

 I'm usually pretty good with electrical (not "electronic") issues, but I've encountered something that has me stumped. My beautiful, low-miles 2000 Cherokee 5-speed was in an accident awhile back. Collision damage was repaired properly, but the insurance didn't cover fixing the ruptured brake lines that actually caused the accident. I finally got around to doing that, using copper-nickel (cunifer) line and silicone brake fluid, so I hope not to have a repeat performance.

Now that it's back on the road, there's an anomaly. Right turn signals blink at the normal rate. Left turn signals blink at the normal rate when the headlights are off, but when the headlights are on, they blink faster. No bulbs burned out. 

Any ideas?

[Boomhauer]

I can’t diagnose issues over the internet but i would say it’s likely a wiring issue that was not fixed. Wires get damaged during collisions harnesses get pinched etc. sometimes not a visibile thing. Time to start ohming out wires and check for shorted wires. Also wiggle the harnesses too. It can take a lot of patience to find the issue but I’m guessing a harness got pinched and mashed some wires together, but not messed up enough to blow fuses

A very helpful book is Dan Sullivan’s fundamentals of electrical troubleshooting, available on Amazon. Cheesy drawings but great info and written on the layman’s level

[p12]

Seen it. Bad ground.

The lights have common ground at various places. When the headlamps are off the turn signal is grounding via the headlamp circuit.

Check the ground for that turn signal and you will find the issue.

If the damage was in the front the ground for that corner is poor.


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[Boomhauer]

Yep grounds will cause all kinds of Fuckery too

[Brad Johnson]

Unplug the headlights at the lamp connection and see if symptoms change. If so, you've narrowed it to the wiring harness at that locale.

Brad

[RoadKingLarry]

Another vote for checking the ground connections.
Or for ye Olde Pharts, the earth connections.

 

[dogmush]

I'm not saying it's the right answer,  but the obvious answer is to swap out the flasher with one of the plug and play electronic flashers that don't use the circuit resistance to time on. Then go on with your life.

But yeah, it's a ground somewhere in that circuit causing the flasher to see the wrong resistance.