reverse/ back up light troubleshooting

[alborz]

stopped at the scale by DOT and complete level one inspection.

back uplight was not working.
I tested the wiring and at the reverse switch at the top of transmission checked the wires. one light up the tester but I think doesn't have enough voltage to light up a bulb .
didn't find a fuse
any help will be appreciated
2010 peterbilt 387
13 Spd eaton trans

[snailexpress]

(05-28-2018 )alborz Wrote:  stopped at the scale by DOT and complete level one inspection.

back uplight was not working.
I tested the wiring and at the reverse switch at the top of transmission checked the wires. one light up the tester but I think doesn't have enough voltage to light up a bulb .
didn't find a fuse
any help will be appreciated
2010 peterbilt 387
13 Spd eaton trans

Back up switch is NO normally open switch. When you put in R it will close relay circuit to the ground and relay will send +12 v to backup light. LCM could be used too.
To check switch - in neutral it should be some voltage present on switch terminal if wire connected or infinity resistance with wire disconnected
In R position 0 volts or 0 ohms accordingly.

[Moose]

I'm having the same problem on a 2014 paccar. Someone told me there is a circuit breaker somewhere but I have yet to find it. I've run a ground separate to the trans switch and I'm still having intermittent issues.

[Moose]

Does anybody on here have access to the Paccar wiring PDFs? I know the CECU plays a big role in this but all the diagrams I have are for my old KW...

I'm still chasing my problem and I'm well into the body and it keeps getting better. Now I have 8vdc at both stop/turn when they're supposed to be 0vdc and I'm still losing the reverse voltage.