Truck Trend Garage: 2002 GMC Yukon Power-Window Failure

Question: The passenger-side power windows on my 4WD 2002 GMC Yukon quit working. What could it be causing the problem?   |   2002 Gmc Yukon power Window Failure Answer: Windows plural is important here. In your Yukon's case, we know that both the right-front and right-rear power window motors are inoperable. Since it's unusual for two of these motors to burn up at the same time, we need to find out what the two components have in common. I pulled up the appropriate wiring schematic with the ALLDATA information system (www.alldata.com). The window motor circuits are a bit complex, so I'll try and keep it simple. The R/F and R/R power window motors receive power (12 volts) and a path to ground through the R/F and R/R window switches, while the master window switch (driver door) supplies just a ground circuit to the front and rear switches to remotely trigger the two passenger-side windows. The windows go up and down by reversing polarity"switching positive and negative"to the motors. There isn't a lot in common with the two windows in question until we take a look at the main power sources for both. The 12 volts come from what's called the RAP#2 relay, while the L/F and L/R windows get power from the RAP#1 relay. A failure at RAP#2 or its related wiring and components explains why both passenger-side windows don't work, but the ones on the left do. RAP stands for Retained Accessory Power and the relays are controlled by the ignition switch and the Body Control Module. The RAP#2 relay is in the fuse block on the right side of the instrument panel and there's a 50-amp fuse marked RAP#2 you can check in the fuse block under the hood. We could guess the exact point of failure, but the circuits should be tested by a pro before replacing any parts. How To Reach Alex
If you have a technical question regarding your pickup, SUV, or van, feel free to contact Alex, a master technician with the National Institute for Automotive Service Excellence. Send a letter to him in care of Truck Trend Garage, 831 S. Douglas Street, El Segundo, CA 90245, or e-mail us at trucktrend@sourceinterlink.com. Please include the VIN with your question. Due to the volume of questions received every month, we cannot guarantee that everyone's question will be personally answered or will appear in the magazine.

Can't wait for help with a problem you're having with your Truck or SUV? Ask the expert we trust here at Truck Trend Garage--visit Alex Steele at www.RealWorldAutomotive.com.