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 reference signals to the headlamp switch through circuits CLF19 (VT/GN), CLF23 (WH/VT), CLS34 (GY) and CLF18 (BU/WH). At any given time, the headlamp switch routes one of the input circuits to ground through circuit GD111 (BK/BU).
When the SJB detects the headlamp switch in the HEADLAMPS ON position with the multifunction switch in the LOW BEAM position, the SJB provides voltage through circuits CLF04 (BN/BU) and CLF05 (BU/GN) to the LH and RH low beam headlamps.
B2A2E-B2498:
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Headlamp switch
- 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.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.
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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
REFER to Autolamps.
No
If equipped with autolamps, GO to D2.
If not equipped with autolamps, GO to D3.
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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.
- Enter the following diagnostic mode on the scan tool: SJB Data Logger.
- NOTE: Only one PID should indicate ON at each headlamp switch position.
- 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 THE HEADLAMP SWITCH
- Ignition OFF.
- Disconnect: Headlamp Switch C205.
- Carry out the headlamp switch component test.
- Is the headlamp switch OK?
Yes
GO to D5.
No
INSTALL a new headlamp switch. REFER to Headlamp Switch Service and Repair. CLEAR the DTCs. REPEAT the self-test.
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D5 CHECK THE HEADLAMP SWITCH GROUND CIRCUIT FOR AN OPEN
- Disconnect: Negative Battery Cable.
- Measure the resistance between the headlamp switch C205-7, circuit GD111 (BK/BU), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to D6.
No
REPAIR circuit GD111 (BK/BU) 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 D9.
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
- Disconnect: SJB C2280e.
- Does the LH or RH headlamp continue to illuminate?
Yes
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.
No
GO to D9.
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D9 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. 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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