Pinpoint Test C: The Interior Courtesy Lamp(s) Are Inoperative
Interior Lighting
Pinpoint Test C: The Interior Courtesy Lamp(s) Are Inoperative
Normal Operation
Power is supplied to the interior courtesy lamps and cargo lamp through the Smart Junction Box (SJB) fuse 9 (15A). Based on the input status from the door ajar switches and the instrument panel dimmer switch, the SJB (Smart Junction Box) supplies voltage to the interior courtesy lamps.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Interior lamp
- Body builder equipment
- SJB (Smart Junction Box)
PINPOINT TEST C : THE INTERIOR COURTESY LAMP(S) ARE INOPERATIVE
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
C1 CHECK THE OPERATION OF ALL THE INTERIOR COURTESY LAMPS
- Ignition OFF.
- Rotate the instrument panel dimmer switch to the DOME LAMP position and observe the interior courtesy lamps.
Are all the interior courtesy lamps inoperative?
Yes
VERIFY the SJB (Smart Junction Box) fuse 9 (15A) is OK.
If OK:
For stripped chassis vehicles, GO to C4.
For vehicles with a single interior courtesy lamp, GO to C5.
For vehicles with multiple interior courtesy lamps, GO to C7.
If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short Electrical Diagrams. After the repair:
If no DTCs are present, TEST the system for normal operation.
If DTC B106E is present, CLEAR the DTCs and REPEAT the self-test (required to enable the courtesy lamp output driver if DTC B106E is present). TEST the system for normal operation.
If DTC B106F is present, INSTALL a new SJB (Smart Junction Box). TEST the system for normal operation.
No
GO to C2.
C2 CHECK FOR VOLTAGE TO THE INTERIOR LAMP
- Rotate the instrument panel dimmer switch out of the DOME LAMP position.
- Disconnect: Inoperative Interior Lamp.
- Rotate the instrument panel dimmer switch to the DOME LAMP position.
- Measure the voltage between the inoperative interior lamp, harness side and ground as follows:
Vehicles With Rear Headliner
Inoperative Lamp Connector-Pin Circuit Front interior/map C929-1 VLN33 (GY/VT) Second row interior/map C981-1 VLN33 (GY/VT) Third row interior/map C901-1 VLN33 (GY/VT) Cargo C926-1 VLN33 (GY/VT)
Vehicles Without Rear Headliner (Except Cutaway)
Inoperative Lamp Connector-Pin Circuit Front interior/map C929-1 VLN33 (GY/VT) Second row interior C957-1 VLN33 (GY/VT) Third row interior C924-1 VLN33 (GY/VT) Auxiliary cargo C993-1 VLN33 (GY/VT) Cargo (part of the high mounted stoplamp) C475-4 VLN33 (GY/VT)
Cutaway Chassis Vehicles
Inoperative Lamp Connector-Pin Circuit Front interior/map C929-1 VLN33 (GY/VT) Body builder C3359-4 VLN33 (GY/VT)
Is the voltage greater than 10 volts?
Yes
For the body builder connector, the vehicle is operating correctly. REFER to the body builder manual to continue diagnosis.
For any other lamp, GO to C3.
No
REPAIR circuit VLN33 (GY/VT) for an open. TEST the system for normal operation.
C3 CHECK FOR VOLTAGE TO THE INTERIOR LAMP USING THE CONNECTOR GROUND
- Measure the voltage between the suspect interior lamp pins, harness side as follows:
Vehicles With Rear Headliner
Inoperative Lamp Connector-Pin/ Circuit Connector-Pin/ Circuit Front interior/map C929-1 VLN33 (GY/VT) C929-2 GD133 (BK) Second row interior/map C981-1 VLN33 (GY/VT) C981-2 GD133 (BK) Third row interior/map C901-1 VLN33 (GY/VT) C901-2 GD133 (BK) Cargo C926-1 VLN33 (GY/VT) C926-2 GD133 (BK)
Vehicles Without Rear Headliner (Except Cutaway)
Inoperative Lamp Connector-Pin Circuit Front interior/map C929-1 VLN33 (GY/VT) C929-2 GD133 (BK) Second row interior C957-1 VLN33 (GY/VT) C957-2 GD133 (BK) Third row interior C924-1 VLN33 (GY/VT) C924-2 GD133 (BK) Auxiliary cargo C993-1 VLN33 (GY/VT) C993-2 GD133 (BK) Cargo (part of the high mounted stoplamp) C475-4 VLN33 (GY/VT) C475-1 GD133 (BK)
Cutaway Chassis Vehicles
Inoperative Lamp Connector-Pin Circuit Front interior/map C929-1 VLN33 (GY/VT) C929-2 GD133 (BK)
Is the voltage greater than 10 volts?
Yes
INSTALL a new interior lamp for the lamp in question. REFER to Interior Lamp Service and Repair. TEST the system for normal operation.
No
REPAIR the ground circuit in question for an open. TEST the system for normal operation.
C4 CHECK THE INSTRUMENT PANEL DIMMER SWITCH INPUT
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB (Smart Junction Box) DataLogger.
- Monitor the SJB (Smart Junction Box) instrument panel dimmer switch PID (DOMELM_SW) while rotating the instrument panel dimmer switch in and out of the DOME LAMP position.
Does the PID agree with the instrument panel dimmer switch position?
Yes
GO to C7.
No
GO to Pinpoint Test B. Pinpoint Test B: The Courtesy Lamps Do Not Turn On From The Instrument Panel Dimmer Switch
C5 CHECK FOR VOLTAGE TO THE FRONT INTERIOR LAMP
- Ignition OFF.
- Disconnect: Front Interior Lamp C929.
- Rotate the instrument panel dimmer switch to the DOME LAMP position.
- Measure the voltage between the front interior lamp C929-1, circuit VLN33 (GY/VT), harness side and ground.
Is the voltage greater than 10 volts?
Yes
GO to C6.
No
GO to C7.
C6 CHECK FOR VOLTAGE TO THE FRONT INTERIOR LAMP USING THE CONNECTOR GROUND
- Measure the voltage between the front interior lamp C929-1, circuit VLN33 (GY/VT), harness side and the front interior lamp C929-2, circuit GD133 (BK), harness side.
Is the voltage greater than 10 volts?
Yes
INSTALL a new interior lamp for the lamp in question. REFER to Interior Lamp Service and Repair. TEST the system for normal operation.
No
REPAIR circuit GD133 (BK) for an open. TEST the system for normal operation.
C7 BYPASS THE SJB (Smart Junction Box)
- Rotate the instrument panel dimmer switch out of the DOME LAMP position.
- Connect: Interior Lamp.
- Disconnect: SJB (Smart Junction Box) C2280A.
- NOTE: If the jumper wire fails, refer to the Wiring Diagrams to identify the possible causes of the circuit short Electrical Diagrams. After the repair, if no DTCs are present, test the system for normal operation. If DTC B106E is present, clear the DTCs and repeat the self-test (required to enable the courtesy lamp output driver if DTC B106E is present). Test the system for normal operation. If DTC B106F is present, install a new SJB (Smart Junction Box). Test the system for normal operation.
Connect a fused jumper wire between the SJB (Smart Junction Box) C2280A-9, circuit VLN33 (GY/VT), harness side and battery positive.
Do the courtesy lamps illuminate?
Yes
REMOVE the jumper wire. GO to C8.
No
REMOVE the jumper wire. REPAIR circuit VLN33 (GY/VT) for an open. CLEAR the DTCs. REPEAT the self-test.
C8 CHECK FOR CORRECT SJB (Smart Junction Box) OPERATION
- Disconnect all the SJB (Smart Junction Box) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB (Smart Junction Box) connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new SJB (Smart Junction Box). TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.