2001 gmc dually trailer brake light problem - The 1947 - Present Chevrolet & GMC Truck Message Board Network

demi · 05-11-2015, 10:30 AM

Hi folks,

I am trying to resolve a problem with my trailer brake light. All of the lights on the truck are functioning correctly. All of the lights on the trailer are functioning correctly except for the driver side brake light.

When I test the prong on the 7-round connector (for the driver side) I am not getting power when the brakes are applied. I do have power for the turn signal and park lights.

I have checked the fuses under hood and inside truck. I know that on 2003 and up trucks there is a module that switches between turn signals and brake lights. On my 2001 I do not have this module #10383321.

Does anyone know if or where there is a relay that controls the turn and brake lights.

Any help would be greatly appreciated, I am stumped or maybe I'm just missing something simple.

Thanks,
demi

GCncsuHD · 05-11-2015, 10:54 AM

So if I'm reading correctly, the left trailer light lights up for the turn signal but not the brake? Since the brake/signal share a wire, it's obviously a problem on the truck. Since you have checked all fuses/connections, and obviously the trailer is good since it lights up for the signal, I would check out the turn signal/multifunction switch. My brother's truck (02 2500HD) had an issue with trailer brake lights not working, but everything else worked. I noticed his hazard button (built into the multifunction switch) was broken, on a whim we replaced it and it fixed the trailer light issue. Apparently the truck signal, trailer signal, and brake light wires all pass through there.

demi · 05-11-2015, 11:28 AM

yes you are correct.
The hazards work fine on the truck and the trailer. Are you suggesting the turn signal/hazard relay thing under the steering wheel?

I will go ahead and check the multifunction switch. I guess that is on the steering column?

GCncsuHD · 05-11-2015, 01:00 PM

Quote:

Originally Posted by demi

yes you are correct.
The hazards work fine on the truck and the trailer. Are you suggesting the turn signal/hazard relay thing under the steering wheel?

I will go ahead and check the multifunction switch. I guess that is on the steering column?

Yea the turn signal stalk/hazard switch/wiper/cruise control etc is all built into the multifunction switch on the steering column.

demi · 05-11-2015, 01:54 PM

Cool I will check that out. Thank you

05-11-2015, 10:54 AM	#2
GCncsuHD Charlie Daniels w/ a Tq Wrench Join Date: May 2009 Location: Statesville, NC Posts: 1,570	Re: 2001 gmc dually trailer brake light problem So if I'm reading correctly, the left trailer light lights up for the turn signal but not the brake? Since the brake/signal share a wire, it's obviously a problem on the truck. Since you have checked all fuses/connections, and obviously the trailer is good since it lights up for the signal, I would check out the turn signal/multifunction switch. My brother's truck (02 2500HD) had an issue with trailer brake lights not working, but everything else worked. I noticed his hazard button (built into the multifunction switch) was broken, on a whim we replaced it and it fixed the trailer light issue. Apparently the truck signal, trailer signal, and brake light wires all pass through there. __________________ ΜΟΛΩΝ ΛΑΒΕ 67 C10 Shortbed "Great Grandpa's Truck" I6 3 on the Tree 71k original miles 5.3 swap in the works 69 K5 Blazer-Family Beach Cruiser Project 78 K30 Dually Semi-Retired Fire Truck 350/SM465 35"s SOLD01 2500HD ECSB 6.0 4x4 5.13's 8" lift 38"s

05-11-2015, 11:28 AM	#3
demi Registered User Join Date: Sep 2003 Location: Arizona Posts: 305	Re: 2001 gmc dually trailer brake light problem yes you are correct. The hazards work fine on the truck and the trailer. Are you suggesting the turn signal/hazard relay thing under the steering wheel? I will go ahead and check the multifunction switch. I guess that is on the steering column? Last edited by demi; 05-11-2015 at 11:31 AM. Reason: added wording

05-11-2015, 01:54 PM	#5
demi Registered User Join Date: Sep 2003 Location: Arizona Posts: 305	Re: 2001 gmc dually trailer brake light problem Cool I will check that out. Thank you

05-11-2015, 10:30 AM	#1
demi Registered User Join Date: Sep 2003 Location: Arizona Posts: 305	2001 gmc dually trailer brake light problem Hi folks, I am trying to resolve a problem with my trailer brake light. All of the lights on the truck are functioning correctly. All of the lights on the trailer are functioning correctly except for the driver side brake light. When I test the prong on the 7-round connector (for the driver side) I am not getting power when the brakes are applied. I do have power for the turn signal and park lights. I have checked the fuses under hood and inside truck. I know that on 2003 and up trucks there is a module that switches between turn signals and brake lights. On my 2001 I do not have this module #10383321. Does anyone know if or where there is a relay that controls the turn and brake lights. Any help would be greatly appreciated, I am stumped or maybe I'm just missing something simple. Thanks, demi



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