Hey guys, been dealing with the driver's power window ever since I got the truck a couple years ago. Finally had enough, and I want to continue the diagnosis and try and determine the cause.

My gut: Th BCU, since the horn doesn't work either and they both route through there.

Here's what I know is fine:
- driver's window regulator
- window motor
- the wires going through the boot cover in the door hinge area
- the switch itself (I swapped with the passenger one, and same problem)

My suspicion is that it's somewhere upstream of the door itself, and upstream of the switch itself. All of the wires 'upstream' go into the BCU, so that's why I'm suspecting this.

Here's the symptoms:
- driver's power window doesn't work at all
- all other windows work great
- horn doesn't work (wheel switches seem fine... related?)
- you can hear the clicking sound as if something is trying to actuate on the window switch, but only when trying to roll it UP. When you click down, there's no sound... completely dead.
- all other window switches you can hear a 'click' on both up and down.

Motor? I suspected that, and I had a new 'used' motor shipped. I had the motor out of the car, and still plugged into the wire harness. I then tried the switch to see if the motor would spin it's little gear, but nothing, on either the motor that was in there or the new motor I got. Either both are duds (unlikely) or there's another problem.

The ultimate reason I'm suspecting the BCU is because the horn doesn't work and it's also routed through it, and the fact that I'm hearing it try to click when pressing up, but nothing when I'm pressing down. This leads me to believe it's an electrical gremlin, rather than something mechanical.

Is there something I'm missing? A relay/fuse? Are there any other tests I can do to rule out other problems? I really hope it's not BCU, cause those things I hear are v. expensive and need to be keyed to the car specifically.

 

Try unplugging tre right connector on the passenger side and plug in the driver side and test. I just happen to have the same issue but the wires got cut inside the boot.

 

The problem could very well be in the harness between the motor and the BCU. I've read about BCUs failing but that seems quite rare.

Last year I was chasing an SRS fault and was about to install a new SRS DCU, but I first tested continuity of the airbag harness and found there was a short in the DCU electrical connector.

Before replacing the BCU I'd try testing continuity between the motor connector and the BCU connector, or operating the window motor directly by unplugging the connector at the BCU and applying power and providing a ground to the correct wires, respectively.

From the door the harness connects behind the driver kick panel to another connector from which the wiring runs to the BCU. That is so the door can be replaced readily without splicing wires. The fault could be there or it could be at the BCU connector.

The RAVE Electrical Library and RAVE Electrical Circuits PDFs are great resources. If you don't have them I recommend searching for and downloading them. It took me a little time and effort to get familiar with using them but I now find myself going to them more and more. Let me know if you'd like any help interpreting them for this effort.

Good luck.