1996 GMC Forward Control 6.5 Y, StandardFACTORY OEM SERVICE PROCEDURE

Left Window Does Not Operate

  1. Disconnect left window switch connector. Disconnect left window motor connector. Connect self-powered test light between Dark Blue wire terminals at left window switch and left window motor connectors. If test light illuminates, go to next step. If test light does not illuminate, repair open in Dark Blue wire between left window switch and left window motor.
  2. Connect self-powered test light between Brown wire terminals at left window switch and left window motor connectors. If test light illuminates, go to next step. If test light does not illuminate, repair open in Brown wire between left window switch and left window motor.
  3. Connect self-powered test light between Dark Blue and Black wire terminals at left window switch connector. If test light illuminates, go to next step. If test light does not illuminate, replace left window switch.
  4. Connect self-powered test light between Brown and Black wire terminals at left window switch connector. If test light illuminates, go to next step. If test light does not illuminate, replace left window switch.
  5. Connect self-powered test light between Yellow wire at left window switch connector and ground. Turn ignition switch to ACC position. If test light illuminates, go to next step. If test light does not illuminate, repair open in Yellow wire between left window switch and fuse block.
  6. Reconnect left window switch connector. Connect test light between ground and Dark Blue wire at left window motor connector. Press left window switch to UP position. If test light illuminates, go to next step. If test light does not illuminate, replace left window switch.
  7. Connect test light between Brown wire at left window motor connector and ground. Press left window switch to DOWN position. If test light illuminates and no mechanical problems exist, replace left window motor. If test light does not illuminate, replace left window switch.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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