SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSGMC1999FORWARD CONTROL 4.3 W, STANDARDREPAIR AND DIAGNOSISBODY & FRAMESEATSPOWER SEAT SYSTEMSYMPTOM TESTSPOWER SEAT DOES NOT MOVE VERTICALLY
1999 GMC Forward Control 4.3 W, Standard

Power Seat Does Not Move Vertically

1999 GMC Forward Control 4.3 W, StandardSECTION Power Seat Does Not Move Vertically
  1. Perform POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING. Go to next step.
  2. If front of seat does not tilt up or down, go to next step. If rear of seat does not move up and down, go to step  14 .
  3. At inoperative seat, disconnect power seat motors connector C-2. Using DVOM, check for continuity between ground and connector C-2 terminal "E" (Dark Green wire). See WIRING DIAGRAMS  . If continuity is indicated, go to step  6 . If continuity is not indicated, go to next step.
  4. Check for open in Dark Green pigtail wire between suspect seat adjuster switch and suspect seat front tilt motor. If circuit is faulty, go to next step. If circuit is okay, go to step  25 .
  5. Repair open in Dark Green pigtail wire between suspect seat adjuster switch and suspect seat front tilt motor. If seat still does not tilt up or down in front, go to next step. After repairs, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
  6. Connect test light between power seat motor connector C-2, terminal "E" (Dark Green wire) and ground. Press power seat front tilt switch to up position. If test light comes on, go to next step. If test light does not come on, go to step  25 .
  7. Using DVOM, check continuity between power seat switch connector C-2, terminal "F" (Dark Blue wire) and ground. If continuity is indicated, go to step  10 . If continuity is not indicated, go to next step.
  8. Check for open in Dark Blue 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  25 .
  9. Repair open in Dark Blue pigtail wire between power seat switch and connector C-2. If seat will still not tilt up or down in front, go to next step. After repairs, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
  10. Connect test light between power seat motor connector C-2, terminal "F" (Dark Blue wire) and ground. Press power seat front tilt switch to down position. If test light comes on, go to next step. If test light does not come on, go to step  25 .
  11. Check for open in pigtail wires between connector C-2 and power seat front tilt motor. If faulty circuit is found, go to next step. If circuits are okay, go to step  13 .
  12. Repair open in pigtail wires between connector C-2 and power seat front tilt motor. If seat will still not tilt up or down in front, go to next step. After repairs, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
  13. Replace suspect power seat front tilt motor. See ADJUSTER MOTORS & DRIVE CABLES  under REMOVAL & INSTALLATION. After repairs, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
  14. Disconnect suspect power seat motors connector C-2. Using DVOM, check continuity between power seat switch connector C-2, terminal "A" (Yellow wire) and ground. If continuity is indicated, go to step  17 . If continuity is not indicated, go to next step.
  15. Check for open in Yellow pigtail wire between power seat switch and connector C-2. If faulty circuit is found, go to next step. If circuit is okay, go to step  25 .
  16. Repair open in Yellow pigtail wire between power seat switch and connector C-2. If seat will still not tilt up or down in the rear, go to next step. After repairs, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
  17. Connect test light between ground and power seat connector C-2 terminal "A" (Yellow wire). Press power seat rear tilt switch to up position. If test light comes on, go to next step. If test light does not come on, go to step  25 .
  18. Use DVOM to check continuity between power seat switch connector C-2, terminal "B" (Light Blue wire) and ground. If continuity is indicated, go to step  21 . If continuity is not indicated, go to next step.
  19. Check for open in Light Blue pigtail wire between power seat switch and connector C-2. If faulty circuit is found, go to next step. If circuit is okay, go to step  25 .
  20. Repair open in Light Blue pigtail wire between power seat switch and connector C-2. If seat will still not tilt up or down in the rear, go to next step. After repairs, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
  21. Connect test light between ground and power seat connector C-2 terminal "B" (Light Blue wire). Press power seat rear tilt switch to down position. If test light comes on, go to next step. If test light does not come on, go to step  25 .
  22. Check for open in pigtail wires between connector C-2 and power seat rear tilt motor. If faulty circuit is found, go to next step. If circuits are okay, go to step  24 .
  23. Repair open in pigtail wires between connector C-2 and power seat rear tilt motor. If seat will still not tilt up or down in the rear, go to next step. After repairs, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
  24. Replace suspect power seat motor. See ADJUSTER MOTORS & DRIVE CABLES  under REMOVAL & INSTALLATION. After repairs, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
  25. Replace suspect power seat switch. See POWER SEAT ADJUSTER SWITCH  under REMOVAL & INSTALLATION. After repairs, go to POWER SEAT SYSTEM CHECK  under TROUBLE SHOOTING.
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

Shop Manual-Ready ToolsFree Quote CheckQuote Shield Pro

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.