Bob - Turn signal and brake light problems #782

[DanEC]

Originally Posted by patrickt

Dan, if you disconnect your trailer relay on the 3-wire "car side," and then turn the car on, and touch the brakes, the RED wire should have a 12v continuous. Take your foot off the brake and put on the left turn signal. The front left light bulb should be flashing and you should get a pulsing 12v at the YELLOW wire. Put the right turn signal on and the right front bulb should now be flashing and you should get a pulsing 12v at the GREEN wire. If this doesn't happen, then there is a problem upstream from your trailer relay -- either a wiring fault or the turn signal switch is bad, or maybe something else. But that's your first diagnostic test. If you can't pass this test, then there's no point in actually removing the trailer relay.

I checked voltage on the red wire coming to the relay from the brake light switch and got 12V when I pushed on the pedal.

I disconnected the leads from the turn signal switch and got these voltage readings.

Turn signals off: 1.5 V left side and 1.3 V right side.

Left signal on: 12 V left side and 1.6 V right side

Right signal on: 12 V right side and 1.9 B left side.

With everything hooked up I get peaks of 9V and lows of about 1.5V with the flasher flashing on the left side. From memory that is what I found to be the case last year when trouble shooting a front turn signal.

With the exception that I don't know if some low voltage bleed over through the turn signal switch is normal or not, it looks like the turn signal is OK.

Comments?

Dan