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HOMESERVICE MANUALSGMC1999FORWARD CONTROL 5.7 R, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 533 (LIGHTING SYSTEMS)DIAGNOSTIC INFORMATION AND PROCEDURESINTERIOR BACKLIGHTING INOPERATIVE
1999 GMC Forward Control 5.7 R, Automatic

Interior Backlighting Inoperative

1999 GMC Forward Control 5.7 R, AutomaticSECTION Interior Backlighting Inoperative
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. However, it is still accessible from the selected car via links, so may be relevant.
Interior Backlighting Inoperative

Step Action Yes No
Schematic Reference:  Interior Lights Dimming Schematics  
Connector End View Reference: Master Electrical Component List in Wiring Systems.
1 Did you perform the Lighting System Diagnostic System Check? Go to Step 2  Go to Diagnostic System Check - Lighting Systems 
2
  1. Turn the ignition to the ON position.
  2. Turn the headlamp switch to the PARK position.
  3. Turn the I/P lamp dimmer switch to a high position.
Are all the I/P lamps ON?		 Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems Go to Step 3 
3 Are all of the instrument panel lamps inoperative? Go to Step 11  Go to Step 4 
4 Are any of the steering wheel control lamps inoperative? Go to Step 5  Go to Step 14 
5 Is one steering wheel control switch illuminated? Go to Step 7  Go to Step 6 
6
  1. Remove both steering wheel control switches.
  2. Probe the I/P lamp supply circuit of each switch with a test lamp connected to ground. Refer to Circuit Testing in Wiring Systems.
Does the test lamp illuminate a each supply circuit?		 Go to Step 9  Go to Step 8 
7
  1. Remove the inoperative switch.
  2. Probe the I/P lamp dimming supply circuit of the inoperative switch with a test lamp connected to ground. Refer to Circuit Testing in Wiring Systems.
Does the test lamp illuminate?		 Go to Step 9  Go to Step 8 
8 Test for a high resistance, short to ground or an open in the I/P dimming lamp supply circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 19  Go to Step 15 
9 Test for a high resistance or an open in the I/P dimming lamp ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 20  Go to Step 15 
10
  1. Disconnect the headlamp switch.
  2. Install a fused jumper between the dimming potentiometer reference voltage circuit and the instrument panel lamps dimming control circuit.
Do the instrument panel lamps turn on?		 Go to Step 18  Go to Step 19 
11 Inspect the instrument panel lamps dimming control circuit for a short to ground, short to battery positive voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 20  Go to Step 12 
12 Inspect the dimming potentiometer reference voltage circuit for high resistance, short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 20  Go to Step 13 
13 Test for a short to ground in the instrument panel lamps supply voltage circuit. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 Go to Step 20  Go to Step 10 
14 Inspect for a high resistance or an open in the inoperative instrument panel lamp component supply voltage circuit or the ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 20  Go to Step 17 
15 Inspect for a poor connection at the harness connector of the steering wheel control switches. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
Did you find and correct the condition?		 Go to Step 20  Go to Step 16 
16 Replace the Inoperative switch. Refer to Steering Wheel Control Switch Assembly Replacement in Steering Wheel and Column.
Did you complete the repair?		 Go to Step 20  -
17 Replace the inoperative component or bulb.
Did you complete the repair?		 Go to Step 20  -
18 Replace the headlamp switch. Refer to Headlamp Switch Replacement  in Instrument, Panel, Gages, and Console.
Did you complete the repair?		 Go to Step 20  -
19
IMPORTANT: Perform the set up procedure for the body control module (BCM). Refer to Body Control Module (BCM) Programming/RPO Configuration in Body Control Systems.
Replace the BCM. Refer to Body Control Module Replacement in Body Control System.Did you complete the replacement?		 Go to Step 20  -
20 Operate the system in order to verify the repair.
Did you correct the condition?		 System OK Go to Step 3 
RENDER: 1.0x

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

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