Turn Signal Oddity

[NEK_VT_FJ60]

When the headlights are off the turn signals and brake lights work fine both front and rear.

But... When the headlights are on the front turn signals work fine, but the rear really go crazy. When I activate the turn signal both rear turn signals and brake lights pulsate in rythym ie all 4 rear lights blink but not all at the same time.

Where should I start looking? Advice?

 

[archie]

Start looking for water or moisture around any place that could be causing a grounding problem(ex.brake lens,headlight connectors,etc..). Look for frayed wires. Check connectors(could be shorted at headlights). Good luck + keep us updated.

 

[60wag]

I'll bet the problem is in the rear. Will the turn signals screw up if just the parking lights are on? I'd pull the rear interior panel on the drivers side to inspect the wiring harness. Does the truck have a trailer hitch on it? If it does, then the PO probably added a trailer light wiring adapter. It could be the source of the problem.

 

[Landpimp]

check the trailer harness if it has one.

 

[fergus]

Check the ground wire on the rear portion of the loom,it's a wire connected to the frame/body under the tailgate area.
HTH