* Window Switch (Master Control): The master switch in the driver's door controls all the windows. A faulty switch is a common cause of multiple window failures. If the driver's side window also isn't working, this is highly suspect.
* Wiring Harness: A break or short in the wiring harness running from the main switch to the rear windows is a possibility. This is particularly likely if the truck has seen rough use, especially near the door jambs where the wires flex frequently. Rodents chewing wires are also a possibility, though less likely to affect both simultaneously.
* Window Regulator Motors: While less likely to fail simultaneously, it's possible both rear window regulator motors have failed. This is mechanical, not just electrical, so it would explain functionality independent of the switches or harness.
* Window Switch (Passenger Side): While less common, the passenger-side door switch could have a problem affecting both rear windows, if it is involved in their operation.
* Body Control Module (BCM): The BCM is a computer that controls many electrical functions in the vehicle. A malfunction in the BCM could affect multiple systems, including the window motors. This is a less likely but possible cause requiring diagnostic tools to assess.
* Ground Connection: A poor ground connection somewhere in the circuit could prevent the power from reaching the motors.
Troubleshooting Steps:
1. Test the Switches: Try all window switches – front and rear (if there are rear switches). If the problem is with the switch, you'll usually need to replace the entire switch assembly.
2. Check Wiring: Visually inspect the wiring harnesses, particularly near the door jambs and where the harness goes into the body. Look for broken wires, frayed insulation, or signs of rodent damage. This may require removing some interior panels.
3. Test Window Motors (if accessible): If you have some electrical experience, you could try to directly test the power going to the window motors. This usually requires removing the door panel and checking the voltage at the motor's connector.
4. Professional Diagnosis: If you're not comfortable with electrical troubleshooting, take your truck to a qualified mechanic or an auto electrician. They'll have the tools to diagnose the problem more precisely, likely using a scan tool to check for BCM issues and wiring faults.
Start with the simplest solutions (switches, visual wiring inspection) before moving to more complex troubleshooting or repairs. The simultaneous failure strongly suggests a common problem in the wiring or control system, rather than a double mechanical failure.
