Non Corvette _ GMC truck

[Kent D.]

[Dennis C.]

Non Corvette _ GMC truck

In our case w/new 06 GMC 3/4 ton - the exact opposite happened. All wires were hooked up, but no fuse was installed to complete the circuit. One fuse solved the issue.
Good luck, Dennis

[William N.]

Re: Non Corvette _ GMC truck

Hi,
Yes there is a wire that is taped back in the wire harness. it is located between the fuse block (UBEC) and the left fender. You unwrap it and connect it to the #2 stud on the front of the Fuse Block or UBEC. This is from bulletin 06-08-45-008.
I tried to scan it in but the scan was too large.
Bill

[Patrick H.]

Re: Non Corvette _ GMC truck

And, I've had a bad trailer light blow the fuse so that the circuit didn't work.

Check for the fuse first, as Dennis notes.

Patrick

[Kent D.]

Re: Non Corvette _ GMC truck

Hi,
Yes there is a wire that is taped back in the wire harness. it is located between the fuse block (UBEC) and the left fender. You unwrap it and connect it to the #2 stud on the front of the Fuse Block or UBEC. This is from bulletin 06-08-45-008.
I tried to scan it in but the scan was too large.
Bill

Thanks Bill for the bulletin, I found the wire just where you said it was but after hooking it up I still have no battery power at the rear bumper, I do have power at the stud on the UBEC so the fuse is good.

[John D.]

Re: Non Corvette _ GMC truck

here's the bulletin


Document ID: 2180085
#06-08-45-008B: Information on Auxiliary Power Wire at Trailer and Installation of Aftermarket Trailer Brake Controller - Towing, Tow - (Aug 19, 2008)

Subject:Information on Auxiliary Power Wire at Trailer and Installation of Aftermarket Trailer Brake Controller -- Towing, Tow

Models:2007-2009 Cadillac Escalade, Escalade ESV, Escalade EXT
2007-2009 Chevrolet Avalanche, Silverado, Suburban, Tahoe
2007-2009 GMC Sierra, Yukon, Yukon Denali, Yukon XL, Yukon Denali XL
2008-2009 HUMMER H2

This bulletin is being revised to add the 2009 model year and the HUMMER H2. Please discard Corporate Bulletin Number 06-08-45-008A (Section 08 -- Body and Accessories).
Important: Installation of an electric brake controller and the wiring connections outlined in this bulletin are the responsibility of the dealership or customer. These repairs should never be charged to warranty. If you have any questions, please consult with your District Service Manager.
Some customers may have questions on how to connect an electric trailer brake controller or where the brake controller pigtail harness is located.
Starting with the new 2007 full-size utilities and pickups and 2008 HUMMER H2, there is no longer an electric trailer brake controller pigtail harness.
An aftermarket brake controller will need to be installed/connected to the blunt wires under the left side of the IP for vehicles built without JL1 - Integrated Brake Controller (full-size utilities and pickups). The JL1 - Integrated Brake Controller option is NOT available on the HUMMER H2. The following steps should be used to complete the installation.

1. 
   
   <LI type=1>Locate the trailer brake control circuits that are looped and taped to the main harness under the instrument panel.
   
   
   <LI type=1>Pull the trailering wire harness down.
   
   
   <LI type=1>Match the vehicle harness label circuit functions to the trailer brake controller jumper harness functions. Important: The color or wires to be joined together may not match.
   

   Dark Blue Wire: switched power from controller to trailer brakes
   Red with Black Stripe: fused vehicle power to electrical brake controller
   Light Blue with White Stripe: Brake switch input to power electric brake controller
   White: ground
   Orange: CHMSL (Center High Mounted Stop Lamp) -- not required with most systems

   
   
   
   <LI type=1>After completing the under dash connections to the electric brake controller, open the hood and locate the red wire that is taped to the harness between the underhood electrical center and the driver side front fender. <LI type=1>Break the tape on the red/black wire and pull it toward the front of vehicle. <LI type=1>Remove the lid from the electrical center.
   
   
2. Place the terminal on the larger of the two studs at the front of the electrical center and secure with an M8 nut. This is circuit #242 to stud #2, to power the aftermarket trailer brake controller. Important: The fuse is already present in the vehicle to power the electrical trailer brake controller system.

Auxiliary Power

Circuit #742 for Auxiliary Power at the 7-way trailer connector is no longer connected by the GM Assembly Plant. If the customer desires auxiliary power at the trailer connector location (i.e. refrigeration, battery charger or interior light in the trailer), complete the following steps to connect circuit #742:

1. <LI type=1>Locate the red/black wire, looped and taped to the chassis harness, below the brake master cylinder. <LI type=1>Break the tape and route the wire to the front of the underhood electrical center.

1. 
   
   <LI type=1>Place the terminal on the smaller of the two studs on the electrical center and secure with an M6 fastener. This is circuit #742 to stud #1 for auxiliary power to the 7-way trailer connector.
2. ONLY for vehicles without RPO TP2 - Auxiliary Battery, install a 40 amp fuse to power the circuit. Important: For vehicles equipped with RPO TP2 -- Devices powered by this fuse will drain the vehicle battery if left connected with the vehicle not running.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.

WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

[Kent D.]

Re: Non Corvette _ GMC truck

Auxiliary Power

Circuit #742 for Auxiliary Power at the 7-way trailer connector is no longer connected by the GM Assembly Plant. If the customer desires auxiliary power at the trailer connector location (i.e. refrigeration, battery charger or interior light in the trailer), complete the following steps to connect circuit #742:

1. <LI type=1>Locate the red/black wire, looped and taped to the chassis harness, below the brake master cylinder. <LI type=1>Break the tape and route the wire to the front of the underhood electrical center.

1. 
   
   
   <LI type=1>Place the terminal on the smaller of the two studs on the electrical center and secure with an M6 fastener. This is circuit #742 to stud #1 for auxiliary power to the 7-way trailer connector.
2. ONLY for vehicles without RPO TP2 - Auxiliary Battery, install a 40 amp fuse to power the circuit. Important: For vehicles equipped with RPO TP2 -- Devices powered by this fuse will drain the vehicle battery if left connected with the vehicle not running.

Thanks John, that is great infomation. This truck already has the factory installed brake controler and the 2nd battery. It's the Circuit #742 for Auxiliary Power that I'm tring to hook up. I have power at stud #1 but no power at the trailer conection.

[Kent D.]

Re: Non Corvette _ GMC truck

OK, I found the corect wire now and I have power at the trailer conection. The wire I was tring to use was between the UBEC and the left fender it had a tag on it that said aftermarket trailer power conection, the corect wire was not labeled.