This 2007 Chevrolet Tahoe LT came in with the complaint that the LBEC2 fuse would blow as soon as it was installed. The owner had tried several with the same result. The two symptoms that the owner noticed that pointed them towards a blown fuse was that the power windows and rear HVAC unit did not work. There were other symptoms but they did not realize what they were when they brought this Tahoe in for repair.
The LBEC2 fuse is located at position #75 in the underhood fuse relay block.
The vehicle came with the low profile or miniature J-Case fuses. During testing I chose to use the standard length fuse as it is easier to install and remove.
As always I consulted a wiring diagram to see how this circuit was laid out. The wiring diagram showed that there was a red/black wire that connects the LBEC2 fuse circuit to the interior fuse block. That fuse block is located behind the end cover at the left end of the dash. The 60 amp LBEC2 fuse supplies power to these fuse circuits:
BCM fuse 10 amp
COOLED SEATS fuse 30 amp
DDM fuse 10 amp and 15 amp
DIM fuse 10 amp
DSM fuse 10 amp
REAR HVAC fuse 30 amp
RT STOP TRN fuse 15 amp
CTSY fuse 15 amp
All of the involved fuses were the correct amperage (all less than 60 amps) and not wrapped with wire or aluminum foil so that meant the short was probably in the wire between the two fuse boxes.
The most likely area would be under the dash, so I started removing the under dash panel so I could begin inspecting the wiring harness. There is a single 10 mm headed screw that attaches the parking brake handle.
Once the screw is removed the handle has to be slid in order to free the hooks on the top side of the handle as shown below.
There are two 7 mm headed screws at either end of the panel that have to be removed.
Then the panel will pull free of the dash. I pulled the upper edge of the panel towards the driver’s seat in order to free the spring tab retainers.
I searched around looking through the openings and found what looked to be the location of the short. I am pointing towards the general area with my pocket screwdriver in the next picture.
I followed that up with inspecting the same area with a mirror and a flashlight. One of the most important things that I have learned over the years is to inspect slowly and re test for the short still being present after each movement of a harness.
And there it is.
To get a better look at the shorted harness I removed the dash fuse block. There are two locks that hold it in place.
The locking tabs have to be pushed down in order to slide the fuse block out of the metal brackets.
A clear look at the spot on the metal bracket where the harness had rubbed through. I repaired the damage to the wire insulation by wrapping it with tape. I then reformed the harness so that it would no longer rub on any brackets.
Another one done.