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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 4.3 W, STANDARDREPAIR AND DIAGNOSISBODY & FRAMESEATSPOWER SEAT SYSTEMSYMPTOM TESTSPOWER SEAT DOES NOT MOVE FORWARD OR REARWARD
1999 GMC Forward Control 4.3 W, Standard

Power Seat Does Not Move Forward Or Rearward

1999 GMC Forward Control 4.3 W, StandardSECTION Power Seat Does Not Move Forward Or Rearward
  1. Perform POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING. Go to next step.
  2. At inoperative seat, disconnect power seat switch connector C-2. Using DVOM, check for continuity between power seat switch connector C-2, terminal "D" (Tan wire) and ground. See WIRING DIAGRAMS  . If continuity is indicated, go to next step. If continuity is not indicated, go to step  4 .
  3. Connect test light between power seat switch connector C-2, terminal "D" (Tan wire) and ground. Press power seat forward/reverse switch lever to forward position. If test light comes on, go to step  6 . If test light does not come on, go to step  13 .
  4. Check for open in Tan pigtail wire between power seat switch and connector C-2. If circuit is faulty, go to next step. If circuit is okay, go to step  13 .
  5. Repair open in Tan pigtail wire between power seat switch and connector C-2. If suspect power seat still does not move forward/backward, go to next step. If suspect seat is okay, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
  6. Using DVOM, check for continuity between power seat switch connector C-2, terminal "C" (Light Green) and ground. If continuity is indicated, go to next step. If continuity is not indicated, go to step  8 .
  7. Connect test light between power seat switch connector C-2, terminal "C" (Light Green) and ground. Press power seat forward/reverse switch lever to reverse position. If test light comes on, go to step  10 . If test light does not come on, go to step  13 .
  8. Check for open in Light Green pigtail wire between power seat switch and power seat forward/rearward motor. If circuit is faulty, go to next step. If circuit is okay, go to step  13 .
  9. Repair open in Light Green pigtail wire between power seat switch and power seat forward/rearward motor. If seat is still inoperative, go to step  7 . After repairs, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
  10. Check for open in pigtail wires between connector C-2 and power seat forward/rearward motor. If faulty circuit is found, go to step  12 . If circuits are okay, go to step  13 .
  11. Repair open in pigtail wires between connector C-2 and power seat forward/rearward motor. After repairs, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
  12. Replace power seat forward/rearward motor. See ADJUSTER MOTORS & DRIVE CABLES  under REMOVAL & INSTALLATION. After repairs, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
  13. Replace suspect power seat switch. See POWER SEAT ADJUSTER SWITCH  under REMOVAL & INSTALLATION. If seat is still inoperative, go to step  7 . After repairs, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
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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.