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How-To: Install Electric Trailer Brake Controller GMT900.

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vette1028 New Member

vette1028

Posted
Posted

JUST BOUGHT A 2009 DENALI PICKUP. IT HAS THE TRAILERING PKG, BUT DOES NOT HAVE THE FACTORY BRAKE CONTROL SWITCH IN THE LWR DASH. DOES ANYONE KNOW IF THE TRUCK IS PREWIRED FOR THE FACTORY SWITCH. I CAN BUY THE SWITCH & LWR DASH PANEL FROM GM BUT NOT SURE IF ANYTHING ELSE IS NEEDED.

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brims Senior Enthusiast

brims

Posted
Posted

It's been tried, there are a LOT of components that are needed. I forget who was going to do it but he gave up seeing how much stuff was needed to add it, plus they don't seem to sell those parts to install the controller after it's been built at the factory, liability or something.

  • 2 months later...
ub2slo Enthusiast

ub2slo

Posted
Posted

Problem, I just installed my brake controller and added the 7 way plug in the bed. When plugged up to the camper the reverse lights come on and stay on. All functions work, tail lights, blinkers, hazards, and brake lights. Anyone have an idea of what could be wrong?

 

Thanks

  • 2 months later...
  • 1 month later...
MattyB4x4 Enthusiast

MattyB4x4

Posted
Posted
the step by step directions are not working.....

 

I just noticed that too. Any way I could get them?

 

Have a trip on Friday and got the controller yesterday.

 

Thanks!

MattyB4x4 Enthusiast

MattyB4x4

Posted
Posted
Here ya go. I happened to save them.

 

GMT900 Prodigy Install Info

 

Its a PDF, so you will need acrobat reader. It is big, so it takes a few seconds to load.

 

C

 

Thank you so so much!!!! I'm working in the dark in my driveway right now. Got everything taken care of but need to run to the hardware store...didn't know what size nuts to get for the two posts on the fuse box.

compulynx Enthusiast

compulynx

Posted
Posted
Problem, I just installed my brake controller and added the 7 way plug in the bed. When plugged up to the camper the reverse lights come on and stay on. All functions work, tail lights, blinkers, hazards, and brake lights. Anyone have an idea of what could be wrong?

 

Thanks

 

Sounds like you got the +12v on the trailer hooked to the center pin. Should be pin 4. Center Pin on a 7 wire is for backup lights on a GMT900. It is labeled "auxillary in this diagram.

 

con3.jpg

 

Just for info, you are looking at the trailer plug from the back, not looking in to it. This is where these diagrams throw a lot of folks....and this is the plug on the trailer, NOT the truck receptacle.

 

This would also be the wiring pattern looking INTO the receptacle on the truck.

 

con2.jpg

 

C

MattyB4x4 Enthusiast

MattyB4x4

Posted
Posted
Here ya go. I happened to save them.

 

GMT900 Prodigy Install Info

 

Its a PDF, so you will need acrobat reader. It is big, so it takes a few seconds to load.

 

C

 

Thank you so so much!!!! I'm working in the dark in my driveway right now. Got everything taken care of but need to run to the hardware store...didn't know what size nuts to get for the two posts on the fuse box.

 

 

 

Got it all hooked up, minus the fuse. Does it make sense that I would have power at the controller without the fuse in? I assume that the fuse has to do with the actual trailer brakes and not the brake controller itself?

 

Thanks again

  • 4 months later...
gerry001 New Member

gerry001

Posted
Posted

Yet another thanks. That was one of the best instruction/info packages that I've seen anywhere. I also liked your mounting approach. A little more work here, as all I could get was steel, but painted to match and it looks good.

  • 3 weeks later...
  • 2 months later...
Jsdirt Senior Enthusiast

Jsdirt

Posted
Posted

I just installed the P3 in my '07 NBS Silverado. On the white wire there's a tag -- it says to connect DIRECTLY to battery ground, or it will result in intermittent operation. I can attest to this. While towing an 18' flatbed with an S10 Blazer on board through hilly backroads , I got full lockup on some applications of the brake, then other times not enough braking. Got real annoying in NY traffic. Light pressure on the pedal would result in violent see-saw action of the truck & trailer on occasion. Didn't happen every time, but enough to be aggravating.

 

Going to see if I can get a wire out there without drilling through the firewall, but more than likely I'll have to drill. Hopefully that will take care of that issue - which I'm thinking it will due to the number of times this is mentioned in the installation instructions, along with the ground wire sticker.

  • 1 month later...
ponchjoe Enthusiast

ponchjoe

Posted
Posted
I just installed the P3 in my '07 NBS Silverado. On the white wire there's a tag -- it says to connect DIRECTLY to battery ground, or it will result in intermittent operation. I can attest to this. While towing an 18' flatbed with an S10 Blazer on board through hilly backroads , I got full lockup on some applications of the brake, then other times not enough braking. Got real annoying in NY traffic. Light pressure on the pedal would result in violent see-saw action of the truck & trailer on occasion. Didn't happen every time, but enough to be aggravating.

 

Going to see if I can get a wire out there without drilling through the firewall, but more than likely I'll have to drill. Hopefully that will take care of that issue - which I'm thinking it will due to the number of times this is mentioned in the installation instructions, along with the ground wire sticker.

 

How did this turn out? I can't find a black wire in the factory harness. Do you have to run a seperate ground?

 

Thanks,

Joe

Doug_Scott Senior Enthusiast

Doug_Scott

Posted
Posted
I just installed the P3 in my '07 NBS Silverado. On the white wire there's a tag -- it says to connect DIRECTLY to battery ground, or it will result in intermittent operation. I can attest to this. While towing an 18' flatbed with an S10 Blazer on board through hilly backroads , I got full lockup on some applications of the brake, then other times not enough braking. Got real annoying in NY traffic. Light pressure on the pedal would result in violent see-saw action of the truck & trailer on occasion. Didn't happen every time, but enough to be aggravating.

 

Going to see if I can get a wire out there without drilling through the firewall, but more than likely I'll have to drill. Hopefully that will take care of that issue - which I'm thinking it will due to the number of times this is mentioned in the installation instructions, along with the ground wire sticker.

 

If there is a wire from the neg term on the battery to the body, then there is no reason the run a dedicated wire to the battery. About the only issue that can come from that is the wire may not be big enough to support all the grounds needed. If you want to make sure it is big enough, simply run a 10 gauge wire from the engine to the master cyl mount (to avoid having to scrape paint off of the body to ensure good connection)

  • 4 weeks later...

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