Pinpoint Test D: The Headlamps Are On Continuously
Headlamps
Pinpoint Test D: The Headlamps Are On Continuously
Refer to Wiring Diagram Set 85, Headlamps/Autolamps for schematic and connector information. Diagrams By Number
Normal Operation
The Lighting Control Module (LCM) sends voltage signals to the headlamp switch to monitor each headlamp switch position. At any given time, one of the input circuits is routed to ground to indicate the headlamp switch position. If the LCM detects a fault with any of the headlamp switch inputs, the LCM defaults the exterior lamps on.
When the LCM detects the headlamp switch in the HEADLAMPS ON position and the multifunction switch in the LOW BEAM position, the LCM provides voltage to the LH and RH low beam headlamps.
When the LCM detects the headlamp switch in the HEADLAMPS ON position and the multifunction switch in the HIGH BEAM position, the LCM provides voltage to the LH and RH high beam headlamps.
The LCM sends a voltage signal to the multifunction switch. When the multifunction switch is placed in the HIGH BEAM position, the voltage signal is routed to ground. When the multifunction switch is placed in the FLASH-TO-PASS position, battery voltage is routed to the LCM. When the LCM detects a request for the flash-to-pass or high beam headlamps, the LCM provides voltage to the high beam headlamps.
- DTC B1472 (Lamp Headlamp Input Circuit Short to Ground) - sets when the LCM detects a short to ground from the headlamps on input circuit.
- DTC B1570 (Lamp Headlamp High-Beam Circuit Short to Ground) - sets when the LCM detects a short to ground from the high beam request input circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Headlamp switch
- Multifunction switch
- LCM
PINPOINT TEST D: THE HEADLAMPS ARE ON CONTINUOUSLY
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
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D1 DETERMINE IF THE HIGH BEAMS ARE ILLUMINATED
- Ignition OFF.
- Place the headlamp switch in the HEADLAMPS ON position.
- While observing the headlamps, place the multifunction switch in the FLASH-TO-PASS position.
- Does the headlamp brightness increase?
Yes
GO to D6.
No
GO to D2.
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D2 CHECK THE MULTIFUNCTION SWITCH
- Ignition OFF.
- Disconnect: Multifunction Switch C202c.
- Do the high beam headlamps continue to illuminate?
Yes
GO to D3.
No
INSTALL a new multifunction switch. REFER to Steering Column Switches Steering Column Multifunction Switch. CLEAR the DTCs. REPEAT the self-test.
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D3 CHECK THE LCM HIGH BEAM OUTPUT CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: LCM C2145c.
- Do the high beam headlamps continue to illuminate?
Yes
REPAIR circuit 1337 (VT/YE) (LH high beam) or circuit 1335 (YE/WH) (RH high beam). CLEAR the DTCs. REPEAT the self-test.
No
GO to D4.
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D4 CHECK THE HIGH BEAM REQUEST INPUT CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: LCM C2145d.
- Ignition ON.
- Measure the voltage between the multifunction switch C202c-10, circuit 12 (LG/BK), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit 12 (LG/BK) for a short to voltage. CLEAR the DTCs. REPEAT the self-test.
No
GO to D5.
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D5 CHECK THE HIGH BEAM REQUEST INPUT CIRCUIT FOR A SHORT TO GROUND
- Measure the resistance between the multifunction switch C202c-10, circuit 12 (LG/BK), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to D12.
No
REPAIR circuit 12 (LG/BK) for a short to ground. CLEAR the DTCs. REPEAT the self-test.
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D6 CHECK THE LCM HEADLAMP SWITCH PIDs
- Place the headlamp switch in the OFF position.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: LCM DataLogger.
- Monitor the LCM headlamp switch PIDs (HLMPOFF, PARK_SW, and HD_LMP_SW) while moving the headlamp switch through all positions.
- Do the headlamp switch PIDs agree with the headlamp switch positions?
Yes
GO to D7.
No
GO to D9.
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D7 CHECK FOR AUTOLAMP DTCs
- Retrieve the recorded results from the LCM self-test.
- Is DTC B1449 or DTC B1696 present?
Yes
REFER to Autolamps Special Tool(s) Used With Diagnostics.
No
GO to D8.
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D8 CHECK THE LCM LOW BEAM OUTPUT CIRCUITS FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: LCM C2145c and C2145d.
- Ignition ON.
- Do the low beam headlamps continue to illuminate?
Yes
REPAIR circuit 160 (DB/WH) (LH low beam) or circuit 161 (DG/OG) (RH low beam). CLEAR the DTCs. REPEAT the self-test.
No
GO to D13.
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D9 CHECK THE HEADLAMP SWITCH
- Ignition OFF.
- Disconnect: Headlamp Switch C205a.
- Carry out the headlamp switch component test.
Refer to Headlamp Switch for component testing.
- Is the headlamp switch OK?
Yes
GO to D10.
No
INSTALL a new headlamp switch. REFER to Headlamp Switch Service and Repair. CLEAR the DTCs. REPEAT the self-test.
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D10 CHECK THE HEADLAMP SWITCH GROUND CIRCUIT FOR AN OPEN
- Disconnect: Negative Battery Cable.
- Measure the resistance between the headlamp switch C205a-7, circuit 57 (BK) harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to D11.
No
REPAIR circuit 57 (BK) for an open. CLEAR the DTCs. REPEAT the self-test.
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D11 CHECK THE HEADLAMP SWITCH INPUT CIRCUITS FOR A SHORT TO GROUND
- Disconnect: LCM C2145a and C2145b.
- Measure the resistance between the headlamp switch, harness side and ground as follows:
- Are the resistances greater than 10,000 ohms?
Yes
GO to D12.
No
REPAIR the circuit in question for a short to ground. CLEAR the DTCs. REPEAT the self-test.
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D12 CHECK THE HEADLAMP SWITCH INPUT CIRCUITS FOR AN OPEN
- Disconnect: LCM C2145a and C2145b.
- Measure the resistance between the headlamp switch, harness side and the LCM, harness side as follows:
- Are the resistances less than 5 ohms?
Yes
GO to D13.
No
REPAIR the circuit in question for an open. CLEAR the DTCs. REPEAT the self-test.
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D13 CHECK FOR CORRECT LCM OPERATION
- Ignition OFF.
- Disconnect all the LCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the LCM 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 LCM. REFER to Multifunction Electronic Modules Lighting Control Module (LCM). 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.
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