2001 GMC 2500HD trailer wiring

[KB9UDE]

I ran a ground straight to the battery. NO help...

I did find that by moving the hazard light switch in the top of the steering column I can make the brake lights work. Seems that switch is bad?? At times the hazards are not functional other times with that switch on all you can hear is the relays chattering...

I think its the hazard switch??

 

[Diamondpilot]

OK, lets start over. How long have you owned this truck and has it ever worked properly?

You say there are no brake lights. How about turn signals and running lights?

Have you thoroughly check the 7 round plug at the rear with a helper and a volt meter? The test light you used is a good start be we need to establish there is good voltage.

I would also take apart the 7 pin plug at the rear of the truck and check things over for bad or corroded connections. If I remember right there have been a few GM owners on here with older trucks such as yours have issues and found that to be the issue.

I wish you lived around the corner. Between the two of us being there we could get you up and running in a few minutes. We could properly diagnose it at my home shop.

I seriously doubt its your hazard switch but anything is possible. Is it working properly if its just the truck, no trailer?

Again I would check the 7 pin plug on your truck. The more I think of it I remember others having internal corrosion problems.


Chris

 

[Soundguy]

my yukon had green stuf fin it's 7 pin plug that had to be cleaned out.. made enough power to fool an LED based plug tester.. but not emough to fire a lamp with a filament.

soundguy

 

[KB9UDE]

When I put a voltage meter on either of the LT or RT pins I get 0 VDC until I wiggle the hazard switch and then I get up to 14v if I am pushing on the brake pedal. All lights on truck work. All lights on trailer work except brake lights until I wiggle the hazard switch. I will have the dealer look at the switch tommorow

 

[Soundguy]

that sounds like a connector issue under that cowling.

soundguy

 

[Diamondpilot]

I guess it is the hazard switch then. New switch should not be that much. May even be just a loose plug on the backside of it.

Chris

 

[KB9UDE]

Dealer says it is the multifunction switch. It includes turn signal and hazard switch.

 

[Diamondpilot]

Dealer says it is the multifunction switch. It includes turn signal and hazard switch.

Keep us informed how it works out and how much it sets you back.

Chris

 

[KB9UDE]

They are saying 650.00 to fix

 

[Diamondpilot]

They are saying 650.00 to fix

Ouch. I would see if I could get one from a junk yard. The steering column is a pain in the rear but maybe worth a try. I have had to take apart two in my time, both on GM trucks. Not the same issue as you but because the cheap soft keys they used back in the 80's. Broke one off and the other wore down so bad I had to change the tumbler with a new key set.

Chris