Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 27 (ANALOG INSTRUMENT PANELS)SYSTEM TESTSTEST Z: INTERIOR BACKLIGHTING DOES NOT DIM
1999 GMC Forward Control 5.7 R, Automatic
Test Z: Interior Backlighting Does Not Dim
1999 GMC Forward Control 5.7 R, AutomaticSECTION Test Z: Interior Backlighting Does Not Dim
WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2001 GMC Savana Special, 2001 GMC Savana Camper Special, 2001 GMC Savana, 2001 Chevrolet RV Cutaway, and 2001 Chevrolet Cutaway. However, it is still accessible from the selected car via links, so may be relevant.
- Perform PRELIMINARY INSPECTION under TROUBLESHOOTING. Go to next step.
- Turn parking lights on. Using thumbwheel, dim instrument panel illumination lights. If illumination lights do not operate properly, go to next step. If illumination lights operate properly, problem may be intermittent. Try to recreate fault by wiggling wiring and connectors. Check for faulty connections at all connectors that may be causing intermittent condition.
- If any parking lights operate properly, go to next step. If no parking lights operate properly, repair as necessary. See EXTERIOR LIGHTS article.
- Disconnect headlight and panel dimmer switch Black 12-pin harness connector. If instrument panel lights are illuminated, go to next step. If instrument panel lights are not illuminated, go to step 6 .
- Remove ILLUM fuse from instrument panel fuse block. If instrument panel lights are illuminated, go to step 7 . If instrument panel lights are not illuminated, go to step 8 .
- Check headlight switch connector for intermittent or poor terminal contact. If terminal contact is okay, go to step 9 . If terminal contact is not okay, repair as necessary. After repair, go to step 10 .
- Repair short to voltage in Gray wire between ILLUM fuse and IPC. After repair, go to step 10 .
- Repair short to voltage in Dark Green wire between headlight switch and ILLUM fuse. After repair, go to step 10 .
- Replace headlight switch. After repair, go to next step.
- Operate system to verify fault no longer exists. If fault still exists, go to step 3 .
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.
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.