1994 Ford Aerostar Factory Trailer Wiring Harness Does Not Power Trailer Brake Lights

Question:

I have a 1994 ford aerostar with the factory trailer wiring harness. I have used this before and all lights worked. I used the same harness on another ford aerostar 1995 and it worked on it. I then switched back to the first van and I cant get the brake lights to come on. I have turn signals but no brake lights. The van has separate brake and turn signals and I have never had to install a three in one device before. Any ideas of what it could be? Some relay that has gone bad maybe?

asked by: Steve

Helpful Expert Reply:

You will want to check the stop light and/or CHMSL fuses in your 1994 Ford Aerostar. That very well could be the issue. There may also be separate fuses or possibly relays related to the tow package wiring. Use the vehicle owners manual to find the locations of any fuses/relays.

If the fuses/relays are all good then it could just be a ground problem. Make sure the vehicle side and trailer side main grounds are attached to clean and corrosion free bare metal surfaces. Also make sure that the connectors are clean and free of corrosion.

On the trailer side will also want to check the grounds at the lights. I have included a link to a help article showing how you can further test the vehicle side wiring harness.

expert reply by: Michael H