Pinpoint Test D: The Low Beam(s) Are Always On
Headlamps
Pinpoint Tests
Pinpoint Test D: The Low Beam(s) Are Always On
Refer to Wiring Diagram Set 85, Headlamps/Autolamps for schematic and connector information. Diagrams By Number
Normal Operation
The Smart Junction Box (SJB) sends voltage signals to the headlamp switch (OFF, PARKING LAMPS and HEADLAMPS). At any given time, the headlamp switch routes one of the input circuits to ground.
When the SJB detects the headlamp switch in the HEADLAMPS ON position (or a fault with one of the headlamp switch input circuits for more than 5 seconds) and the multifunction switch in the LOW BEAM position, the SJB provides voltage to the low beam headlamps.
Vehicles equipped with High Intensity Discharge (HID) headlamps utilize a second (hot at all times) voltage feed to the HID ballasts.
When the ballasts receive the headlamp on voltage from the SJB, the ballasts provide high voltage to the HID bulbs.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Headlamp switch
- Ballast
- SJB
PINPOINT TEST D: THE LOW BEAM(S) ARE ALWAYS ON
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 CHECK FOR AUTOLAMP DTCs
- Review the DTCs retrieved from the SJB self-test.
- Is DTC B1696, B1791, B1793 or B2008 present?
Yes
GO to Pinpoint Test H Pinpoint Test H: The Autolamps Are On Continuously.
No
GO to D2.
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D2 CHECK THE SJB AUTOLAMP ON REQUEST PID
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB Data Logger.
- While placing the headlamp switch in the AUTOLAMPS ON and then OFF position, monitor the SJB headlamp switch PID (HDLMP_AUT_CKT).
- Does the PID indicate ON with the headlamp switch in the AUTOLAMPS ON position and OFF when the headlamp switch is in the OFF position?
Yes
GO to D3.
No
GO to Pinpoint Test H Pinpoint Test H: The Autolamps Are On Continuously.
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D3 CHECK THE SJB HEADLAMP SWITCH PIDs
NOTE: Make sure the headlamp switch is lined up in the correct position when monitoring the PIDs.
NOTE: Only one PID should indicate ON at each headlamp switch position.
- Enter the following diagnostic mode on the scan tool: SJB Data Logger.
- While moving the headlamp switch through all positions, monitor the SJB headlamp switch input PIDs (HDLMP_OFF_CKT, HDLMP_PRK_CKT, HDLMP_ON_CKT).
- Do the headlamp switch positions agree with the PIDs (with only one PID indicating ON in each position)?
Yes
GO to D8.
No
GO to D4.
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D4 CHECK FOR VOLTAGE TO THE HEADLAMP SWITCH
- Ignition OFF.
- Disconnect: Headlamp Switch C205.
- Ignition ON.
- Measure the voltage between the headlamp switch, harness side and ground as follows:
- Are the voltages greater than 10 volts?
Yes
GO to D5.
No
GO to D6.
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D5 CHECK FOR VOLTAGE BETWEEN THE OFF CIRCUIT AND GROUND
- Measure the voltage between the headlamp switch C205-6, circuit CLF23 (WH/VT), harness side and headlamp switch C205-3, circuit GD116 (BK/VT), harness side.
- Is the voltage greater than 10 volts?
Yes
INSTALL a new headlamp switch. REFER to Headlamp Switch Service and Repair. CLEAR the DTCs. REPEAT the self-test.
No
REPAIR circuit GD116 (BK/VT) for an open. CLEAR the DTCs. REPEAT the self-test.
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D6 CHECK THE HEADLAMP SWITCH INPUT CIRCUITS FOR A SHORT TO GROUND
- Disconnect: SJB C2280b.
- Measure the resistance between the headlamp switch, harness side and ground as follows:
- Are the resistances greater than 10,000 ohms?
Yes
GO to D7.
No
REPAIR the circuit in question for a short to ground. CLEAR the DTCs. REPEAT the self-test.
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D7 CHECK THE HEADLAMP SWITCH INPUT CIRCUITS FOR AN OPEN
- Measure the resistance between the headlamp switch, harness side and the SJB, harness side as follows:
- Are the resistances less than 5 ohms?
Yes
GO to D10.
No
REPAIR the circuit in question for an open. CLEAR the DTCs. REPEAT the self-test.
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D8 CHECK THE SJB OUTPUT
- Ignition OFF.
- Disconnect: SJB C2280e.
- Ignition ON.
- Does the LH or RH headlamp continue to illuminate?
Yes
For vehicles with halogen headlamps, REPAIR circuit CLF04 (BN/BU) (LH headlamp) or circuit CLF05 (BU/GN) (RH headlamp) for a short to voltage as necessary. CLEAR the DTCs. REPEAT the self-test.
For vehicles with HID headlamps, GO to D9.
No
GO to D10.
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D9 CHECK THE SJB LOW BEAM OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: Illuminated Headlamp.
- Ignition ON.
- Measure the voltage between the LH headlamp C1284-1 circuit CLF04 (BN/BU), harness side and ground; or between the RH headlamp C1285-1 circuit CLF05 (BU/GN), harness side and ground.
- Is any voltage present?
Yes
REPAIR circuit CLF04 (BN/BU) (LH headlamp) or circuit CLF05 (BU/GN) (RH headlamp) for a short to voltage. CLEAR the DTCs. REPEAT the self-test.
No
INSTALL a new ballast. REFER to Ballast Service and Repair. TEST the system for normal operation.
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D10 CHECK FOR CORRECT SJB OPERATION
- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB 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. REFER to Multifunction Electronic Modules Service and Repair. 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. CLEAR the DTCs. REPEAT the self-test.
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