reedbr

I've been searching thru the forums for an hour and haven't seen anything. So i'm starting a thread.

I've got a 2007 LTZ Suburban with a factory towing package & hitch system. I've purchased and installed an Reliance Brake Force Brake Controller and wired it to the 4 wires that are hanging under the dash. Red/Black =+12v, White = ground, Dark Blue = Trailer brakes, Blue/White = Brake Pedal Switch.

Problem = the controller isn't working.

I've ohm tested from under the dash to the 7 terminal connector on the bumber and the Dark Blue wire is correct.

I've voltage tested the blue/white wire and i get +12vdc when i push on the brake pedal which is correct.

When I ohm test the white wire to chassis ground or to the negative battery post i get >> 1,000,000 ohnms. So i'm confused.

When i voltage test the red/black wire to chassis ground i get 0v. So i'm confused.

when i look under the hood in the fuse box there are 4 fuses on the right that are supposed to be for the trailer lights, etc. Using a test light i do not have any power to either side of the fuse. all of the fuses are good..

any ideas.

reedbr

i looked and between the fuse box and fender i saw a red/black wire taped to the harness. i removed the tape and it had a large ring terminal on the end of it.
i ohm tested it to the red/black wire i connected the controller to and read 0.24 ohms. so i've got the power wire under the hood. from the size of the factory ring terminal i suppose it gets landed on one of the two large studs on the front of the fuse box (bumper side). but both of the two studs have constant 12v and i would think i would want both a fused and switched 12v.

i'm still confused about the white wire that is supposed to be ground.

thoughts?

in2pro

Welcome to the forum..
see if this helps... it looks like the white is the ground...
Attached PDF

reedbr

thanks for the help. i performed a resistance check between the white wire and chassis ground which showed the wire was not connected to chassis ground (open). Since i was able to figure out the red/black wire needed connected at the fuse box i just went ahead and ran my own ground wire from the chassis under the dash to the new brake controller. the controller is working, but i'm still concerned the red/black wire being terminated on the fuse box constant 12v without a fuse. i may add an inline fuse just to be safe. thanks again for the help.

{tpc}

Very strange that the white wire wasn't connected to ground. I would say maybe there is a fuse at some point in play there but I'm not sure you would fuse the ground side.

At any rate, on my 07 tahoe there are two wires that are taped to harness's under the hood that need to be connected to the fuse block studs. I want to say one is for the brakes on the trailer, and the other is used to charge charge the trailer battery off the trucks alternator.

I found one on the left side of the fuse block and one on the right side. I'm fairly certain they are both fused inside the fuse block, but I could be wrong.

in2pro

When you pull off the under hood fuse cover you will see 2 studs toward the front of the vehicle, the fuses for them are the 30amp and 40amp next to them. Those wires go to those respective studs... I do not have a BC so I use the other stud to charge my camper battery in the aux battery tray...

Brady

SOLUTION: There are two wires under the hood that have to be connected to make the tow package functional, one is the power wire to the brake control and the other is the battery charge line to the 7 way connector. These wires are both Red/Black with eyelets on them. They are coiled up under the hood and will need to be connected to the under hood fuse box. One of the wires is located between the under hood fuse box and the left (driver) side fender. The other is located under the master cylinder/brake booster assembly.

fuse box under the hood

The battery charge wire and the power wire to the brake control have different size eyelets on them and will connect to the threaded studs under the Gray handle at the front of the fuse box. The two studs are also different size.

Note: GM does not supply the attaching nut required to secure the wires to the studs. These can be obtained locally. You will need (1) M6 x 1.0 nut and (1) M8 x 1.25 nut.

CAUTION: Raising the Gray handle more than 3/8 of an inch to gain access to the studs may result in the fuse box coming disconnected from the electrical connector. If disconnection occurs you may have to consult your local GM dealership for repairs.

Here is a link to etrailer with photos.
Installing an Electric Brake Controller on 2007-2013 GM Full-Size Truck or 2007-Present GM SUV | etrailer.com

intheburbs

Or, if you disconnect the ground wire from the battery (as is prudent any time you're doing electrical work), you don't have to worry about lifting the fuse tray too far.