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Home >> GMC >> 2001 >> C3500 HD 6.5 F, Standard >> Repair and Diagnosis >> Accessories & Equipment >> Interior/Illumination Lights >> Lighting Systems >> Diagnostic Information and Procedures >> Courtesy Lamps Inoperative (With RPO Y91)

Courtesy Lamps Inoperative (With RPO Y91)

Courtesy Lamps Inoperative (With RPO Y91)

Step Action Value(s) Yes No
Schematic Reference: Interior Lights Schematics (Base Utility) , Interior Lights Schematics (Base Pickup) , Interior Lights Schematics (Uplevel Pickup) , Interior Lights Schematics (Uplevel and Luxury (Y91) Utility) 
1 Did you perform the Lighting Diagnostic System Check?   Go to Step 2  Go to Diagnostic System Check - Lighting Systems 
2 Operate the courtesy lamps to verify the fault is present.
Does the system operate normally?		   Go to Testing for Electrical Intermittents in Wiring Systems Go to Step 3 
3 Is only one lamp inoperative?   Go to Step 4  Go to Step 6 
4 Test the courtesy lamps PWM supply voltage circuit of the inoperative lamp for high resistance, an open, or a short to ground. Refer to Circuit Testing , and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		   Go to Step 35  Go to Step 5 
5 Test the ground circuit of the inoperative lamp a high resistance, or an open. Refer to Circuit Testing , and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		   Go to Step 35  Go to Step 21 
6
  1. With the scan tool, read the dome override switch status.
  2. Change the dome lamp override switch between the ON and OFF positions several times.
Does the scan tool display the switch status as expected?		   Go to Step 9  Go to Step 7 
7
  1. Disconnect the headlamp and panel dimmer switch.
  2. With the scan tool, read the dome override switch status.
Does the scan tool display the switch status as OFF?		   Go to Step 8  Go to Step 20 
8 Test the ground circuit to the headlamp switch for high resistance, or an open. Refer to Circuit Testing , and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		   Go to Step 35  Go to Step 22 
9
  1. Ensure that the dome override switch is in the OFF position.
  2. Place the dome lamp switch in the ON position.
  3. With the scan tool, observe the courtesy lamp switch data parameter.
Does the scan tool display ON?		   Go to Step 11  Go to Step 10 
10 Test the courtesy lamps on signal circuit of the headlamp switch for a short to voltage, short to ground, a high resistance, or an open. Refer to Circuit Testing , and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		   Go to Step 35  Go to Step 22 
11
  1. Open the drivers door.
  2. With the scan tool, read the drivers door jamb switch status.
Does the scan tool display the switch status as Active?		   Go to Step 14  Go to Step 12 
12
  1. Disconnect the appropriate mini wedge or door jamb switch.
  2. Connect a fused jumper wire between the door jamb switch signal circuit and the ground circuit of the door jamb switch.
  3. With the scan tool, read the appropriate door jamb switch status.
Does the scan tool display the switch status as Active?		   Go to Step 23  Go to Step 13 
13
  1. Connect a fused jumper wire between the door jamb switch signal circuit and a good ground.
  2. With the scan tool, read the appropriate door jamb switch status.
Does the scan tool display the switch status as Active?		   Go to Step 27  Go to Step 19 
14 Test the courtesy lamps PWM supply voltage circuit of the courtesy lamps module for a high resistance, an open, or a short to ground. Refer to Circuit Testing , and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		   Go to Step 35  Go to Step 15 
15
  1. Remove the courtesy lamp module.
  2. Connect a test lamp between the inadvertent power supply voltage circuit and the ground circuit of the courtesy lamp module.
Does the test lamp illuminate?		 Go to Step 16  Go to Step 18 
16
  1. Measure the voltage from the courtesy lamp low control circuit of the courtesy lamp module to a good ground.
  2. Open the drivers door.
Does the voltage measure near the specified voltage?		 0 Volts Go to Step 24  Go to Step 17 
17 Test the courtesy lamps low control circuit of the courtesy lamps module for a high resistance, an open, or a short to voltage. Refer to Circuit Testing , and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		   Go to Step 35  Go to Step 26 
18
  1. Reinstall the courtesy lamp module.
  2. Remove the inadvertent power relay.
  3. Connect a fused jumper wire between the fused battery positive circuit and the inadvertent power relay output circuit at the relay socket.
  4. Open drivers door.
Do the courtesy lamps light?		   Go to Step 25  Go to Step 28 
19 Test the door jamb switch signal circuit between the mini wedge and the body control module (BCM). Refer to Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		   Go to Step 35  Go to Step 26 
20 Test the interior lamp defeat switch signal circuit of the BCM for a short to ground. Refer to Circuit Testing , and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		   Go to Step 35  Go to Step 26 
21 Inspect for poor connections at the harness connector of the courtesy lamp. 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 35  Go to Step 29 
22 Inspect for poor connections at the harness connector of the headlamp switch. 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 35  Go to Step 30a 
23 Inspect for poor connections at the harness connector of the mini wedge. 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 35  Go to Step 31 
24 Inspect for poor connections at the harness connector of the courtesy lamp module. 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 35  Go to Step 32 
25 Inspect for poor connections at the harness connector of the inadvertent power relay. 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 35  Go to Step 33 
26 Inspect for poor connections at the harness connector of the BCM. 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 35  Go to Step 34 
27 Repair the open in the ground circuit. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		   Go to Step 35  -
28 Repair the inadvertent power supply voltage or ground circuits of the courtesy lamp module. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		   Go to Step 35  -
29 Replace the inoperative courtesy lamp.
Did you complete the repair?		   Go to Step 35  -
30 Replace the headlamp and panel dimmer switch. Refer to Headlamp Switch Replacement .
Did you complete the replacement?		   Go to Step 35  -
31 Replace the appropriate mini wedge, door jamb switch. Refer to Front Side Door Lock Actuator Replacement in Doors.
Did you complete the replacement?		   Go to Step 35  -
32 Replace the courtesy lamp module. Refer to Lamp Control Module Replacement .
Did you complete the replacement?		   Go to Step 35  -
33 Replace the inadvertent power relay.
Did you complete the replacement?		   Go to Step 35  -
34
IMPORTANT:

Perform the setup procedure for the body control module.

Replace the body control module. Refer to Body Control Module Replacement in Body Control System.Did you complete the replacement?		   Go to Step 35  -
35 Operate the system in order to verify the repair.
Did you correct the condition?		   System OK Go to Step 3 
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