suburban trailer wiring harness

sledrace · August 27, 2005

I have a 2003 suburban 1500 2wd factory wiring harness, plug and hitch. Tekonsha prodigy brake controller. I have working charging system, signal, running, brake lights and working electric brakes. Problem: no voltage at the plug on the truck for charging the trailer batteries. I think I have isolated the correct fuse under the hood but 3 dealers and the GM help line were unable to tell me exactly which fuse it is. The trailer wiring matches the truck wiring. I was told by one dealer that GM had trouble with corrosion on the in the trailer plug. I took the the plug apart and the wires are molded into the plug. No way to check them without cutting the wire. I tried sticking a pin in the 12 volt wire to check continuity between the wire and and the pin inside the plug but the wire and coating are so hard I kept breaking the pin. How do I find the correct fuse under the hood. My 88 suburban was a cinch. The 12 volt wire was not buried in a wiring harness and ran separatley with a bayonette fuse. Any ideas

GM-Tech · August 27, 2005

Does this help?

sledrace · August 28, 2005

I have a 2003 suburban 1500 2wd factory wiring harness, plug and hitch. Tekonsha prodigy brake controller. I have working charging system, signal, running, brake lights and working electric brakes. Problem: no voltage at the plug on the truck for charging the trailer batteries. I think I have isolated the correct fuse under the hood but 3 dealers and the GM help line were unable to tell me exactly which fuse it is. The trailer wiring matches the truck wiring. I was told by one dealer that GM had trouble with corrosion on the in the trailer plug. I took the the plug apart and the wires are molded into the plug. No way to check them without cutting the wire. I tried sticking a pin in the 12 volt wire to check continuity between the wire and and the pin inside the plug but the wire and coating are so hard I kept breaking the pin. How do I find the correct fuse under the hood. My 88 suburban was a cinch. The 12 volt wire was not buried in a wiring harness and ran separatley with a bayonette fuse. Any ideas

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GM-Tech · August 28, 2005

That's a rather odd reply.

sledrace · August 28, 2005

Does this help?

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Thank you for researching this but I found my answer.Sorry about that I hit the wrong button. I found the answer yesterday after hours of searching. Some guy that had an 03 and an airstream had the same problem. Seems GM changed everything around in 03 but never told anyone. Now it seems if they did this with my truck why didn't they do it on everyone? Then the dealers would have found out about when every new suburban ordered would have been brought in for diagnosis of the problem I had. Why the 3 dealers or the GM tech line didn't know about it I don't know. The vehicle has a factory towing package which includes hitch and wiring. This didn't even appear in the manual. There is no fuse or breaker. You have to buy one and put it in. Under the hood in the fuse box on the top left there is a red plastic plug in a terminal labeled STUD 1 or blank labeled with a capital B+. On the right there is a terminal labeled STUD 2 (auxiliary power/trlr brakes). Auxiliary power is what screwed me up. The owners manual says don't use a fuse in STUD 1 but it also doesn't say "but use a breaker. Now the packaging that the breaker came in was labeled fuse when in fact it's a breaker. How many people would know whether they bought the right part. I added a 40 amp breaker and guess what I have power at that wire. I was so close to cutting the plug since the wires were molded in. That's like not putting a fuse in the radio that comes with the truck.