ABS trailer light on dash never worked
I have a 2001 Freightliner Columbia. The truck ABS light works with key on self test. The trailer ABS light has never worked since I have had the truck. Yes the lamp is good.
The ABS light on the trailer works with key on self test and with brakes applied key off.
My experience as an electronics tech tells me that there should be a connection between truck and trailer for a signal to turn dash light on but I cannot find one in the pigtail.
How does the truck "know" there is an ABS problem?
white = ground
black= power marker lights
brown = power tail lights
yellow = left turn
green = right turn
red = stop
blue = power key on
Is this a good question?