Right Blinkers Come On When Brakes Applied

evanssce · March 29, 2009

My 2000 Yukon XL's right turn signals illuminate (front, rear, and dash) every time the brake pedal is depressed. I have checked all the fuses and all the bulbs on the right side (front and back). The local dealer said it is probably something to do with my aftermarket towing harness for electric trailer brakes but there was no change after disconnecting the harness.

silveradobobby · March 29, 2009

Sounds like there is water in one of the light sockets causing a short or a bad bulb. Try taking a bulb out one at a time and see if the issue goes away.

ScottyBoy · March 29, 2009

Do the brake lights also blink when the right turn signal is used? If so you have wires crossed somewhere. Either someone didnt't correctly install the trailer harness or you have a bad bulb/socket in your rear right tail light. You said you removed the harness for the electric brakes. Did you just remove the harness under the dash for the brake controller? Or did you remove the actual light harness near the towing hitch? My boss just had this same issue on his Tundra. It has seperate brake and turn signal bulbs just like a yukon. Most trailer lights share the same wire/bulb for the turn signal and brake lights. So if the installer didn't realize this he could have very easily connected the brake and turn signal wires together. Thats exactly what was wrong with my boss's truck. He had to unwrap the electric tape where the trailer light plug was tied in with the factory wiring undr the truck, and sure enough, the two wire were connected together at the turn signal wire on the harness. When wiring up a truck with seperate brake and turn signal bulbs, you have to buy an adapter to get it to work right.

evanssce · April 8, 2009

Do the brake lights also blink when the right turn signal is used? If so you have wires crossed somewhere. Either someone didnt't correctly install the trailer harness or you have a bad bulb/socket in your rear right tail light. You said you removed the harness for the electric brakes. Did you just remove the harness under the dash for the brake controller? Or did you remove the actual light harness near the towing hitch? My boss just had this same issue on his Tundra. It has seperate brake and turn signal bulbs just like a yukon. Most trailer lights share the same wire/bulb for the turn signal and brake lights. So if the installer didn't realize this he could have very easily connected the brake and turn signal wires together. Thats exactly what was wrong with my boss's truck. He had to unwrap the electric tape where the trailer light plug was tied in with the factory wiring undr the truck, and sure enough, the two wire were connected together at the turn signal wire on the harness. When wiring up a truck with seperate brake and turn signal bulbs, you have to buy an adapter to get it to work right.

No. The brake lights do not blink when the right turn signal is used. I removed the harness from under the dash. The rear harness has an adapter and the trailer lights and brakes worked fine the last time they were used a year ago. I have already removed all of the bulbs on the right side and I still get an illuminated right turn arrow on the instrument panel when the brakes are applied.

bill190 · April 8, 2009

Try "giggling" your turn signal switch and also try turning on/off the hazard flasher switch.

I don't have the wiring diagram for your year, but with older vehicles, the stop lights were switched through the turn signal switch and also related to the hazard switch.

If that does not give a clue as to the problem, then get out the multimeter and factory wiring diagrams...