Same Old Brake Controller Wiring Problem

JoeyCrash2 · July 10, 2007

I just got a used 2004 Silverado 1500 and I'll be damned if I can get my brake controller to work. I've looked all over these forums and can't get a clear definition of how to do it. It's got the "factory towing package" or whatever there is of it. I ordered the wiring adapter for the under dash block, hooked it up to the brake controller, installed the 40amp maxi fuse in stud 1 location and I still get nothing. The brake controller has power and if I squeeze the manual control I can get a reading, though the brakes don't actually go on on the trailer. The brake pedal doesn't activate the brake controller at all. I know the trailer works because I've hooked it up to another truck and everything is fine. I'm totally dumbfounded. Can anyone provide clear and concise instructions for wiring pertaining to the under dash block, UBEC (fuse box under hood) and whatever else I might need to know to get this thing to work. Pictures of the UBEC setup would probably help too. I've seen some posts where someone posted a pic of the proper wiring, but that picture is no longer available in whatever forum it was in.

Thanks a bunch,

Joe.

GMTRUCKTECH · July 10, 2007

WHAT IS THE PART NUMBER OR TAG NUMBER ON THE TRAILER HARNESS YOU ORDERED CAUSE IT COULD BE WRONG. YOU NEED THIS HARNESS FOR A O4 The 2003-05 jumper is P/N 15085418. The orange tag identifier is 5418 LET ME KNOW

plainvanilla · July 10, 2007

I just got a used 2004 Silverado 1500 and I'll be damned if I can get my brake controller to work. I've looked all over these forums and can't get a clear definition of how to do it. It's got the "factory towing package" or whatever there is of it. I ordered the wiring adapter for the under dash block, hooked it up to the brake controller, installed the 40amp maxi fuse in stud 1 location and I still get nothing. The brake controller has power and if I squeeze the manual control I can get a reading, though the brakes don't actually go on on the trailer. The brake pedal doesn't activate the brake controller at all. I know the trailer works because I've hooked it up to another truck and everything is fine. I'm totally dumbfounded. Can anyone provide clear and concise instructions for wiring pertaining to the under dash block, UBEC (fuse box under hood) and whatever else I might need to know to get this thing to work. Pictures of the UBEC setup would probably help too. I've seen some posts where someone posted a pic of the proper wiring, but that picture is no longer available in whatever forum it was in.

Thanks a bunch,

Joe.

my factory supplied harness was wired wrong!

THe main power wire coming from the fuse center was right on the truck but the harness had two wires backwards, I would have never figured it out. I had a service tech who knew his stuff come out on the curb and find the problem in about 5 minutes, swapped the wires and it worked.

dichdoc · July 10, 2007

Are you plugging straight in or using an adapter. I wired mine all up and went to plug in to a trailer with a small 6 pin round with an adapter and the brakes were on solid. I had to pull the adapter apart and swap the blue and the black wire (the only two that were set with screws and not soldered). Just a thought. TB

JoeyCrash2 · July 10, 2007

I just got a used 2004 Silverado 1500 and I'll be damned if I can get my brake controller to work. I've looked all over these forums and can't get a clear definition of how to do it. It's got the "factory towing package" or whatever there is of it. I ordered the wiring adapter for the under dash block, hooked it up to the brake controller, installed the 40amp maxi fuse in stud 1 location and I still get nothing. The brake controller has power and if I squeeze the manual control I can get a reading, though the brakes don't actually go on on the trailer. The brake pedal doesn't activate the brake controller at all. I know the trailer works because I've hooked it up to another truck and everything is fine. I'm totally dumbfounded. Can anyone provide clear and concise instructions for wiring pertaining to the under dash block, UBEC (fuse box under hood) and whatever else I might need to know to get this thing to work. Pictures of the UBEC setup would probably help too. I've seen some posts where someone posted a pic of the proper wiring, but that picture is no longer available in whatever forum it was in.

Thanks a bunch,

Joe.

my factory supplied harness was wired wrong!

THe main power wire coming from the fuse center was right on the truck but the harness had two wires backwards, I would have never figured it out. I had a service tech who knew his stuff come out on the curb and find the problem in about 5 minutes, swapped the wires and it worked.

yeah, my harness was wired incorrectly as well - or the truck is wrong. I think the GM layout is supposed to be

|---------------------------|

| Trailer Brakes | Stop Lamp |

|--------------|------------|

| +12V |xxxxxxxxxxx |

|--------------| -----------|

| xxxxxxxxxxxxx | Ground |

|---------------------------|

But I found the layout was different and had to rewire the controller adapter to the following:

|------------------------------|

| Stop Lamp | Trailer Brakes |

|---------------|--------------|

| xxxxxxxxxxxxx | +12V |

|---------------|--------------|

| xxxxxxxxxxxxx | Ground |

|------------------------------|

Almost completely flipped. I don't know if it's right, but it's the only configuration that allows the controller to function at all.

JoeyCrash2 · July 10, 2007

Are you plugging straight in or using an adapter. I wired mine all up and went to plug in to a trailer with a small 6 pin round with an adapter and the brakes were on solid. I had to pull the adapter apart and swap the blue and the black wire (the only two that were set with screws and not soldered). Just a thought. TB

Here's the deal with that - The truck came with the wiring harness all factory installed - sans fuse in stud 1, blue and red wires in UBEC not hooked to anything. But someone used a 7 pole trailer connection at some point because there is one at the rear of the truck clicked with an adapter into the factory harness. The 7 pole is made by U-Haul and has all the standard wiring colors so I (possibly foolishly) assume it's wired correctly and that I was just missing said fuse. But I don't know what to do with the two wires in the UBEC. I read that the red wire is supposed to connect to Stud 1 or 2 for power to the break controller - but I already have power to the brake controller without it...very strange.

Robble · July 11, 2007

I use to work at a camping trailer dealer and use to install brake controllers all day. However, that was a while ago I remember having to switch wires on some of the harnesses. Also, it is easy to blow a brake controller. especially if you don't ground it first.