Pinpoint Test E: The Low Beam(S) Are Always on
Headlamps
Pinpoint Tests
Pinpoint Test E: 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 - Halogen Low Beam Headlamps
The Smart Junction Box (SJB) sends reference signals to the headlamp switch through circuits CLF18 (BU/WH), CLF19 (VT/GN), CLF23 (WH/VT) and CLS34 (GY). At any given time, the headlamp switch routes one of the input circuits to ground through circuit GD116 (BK/VT).
When the SJB detects the headlamp switch in the HEADLAMPS ON position and the multifunction switch in the LOW BEAM position, the SJB sends voltage through circuit CLF04 (BN/BU) and circuit CLF05 (BU/GN) to the LH and RH low beam headlamps.
High Intensity Discharge (HID) Low Beam Headlamps
The SJB sends reference signals to the headlamp switch through circuits CLF18 (BU/WH), CLF19 (VT/GN), CLF23 (WH/VT) and CLS34 (GY). At any given time, the headlamp switch routes one of the input circuits to ground through circuit GD116 (BK/VT).
When the SJB detects the headlamp switch in the HEADLAMPS ON position and the multifunction switch in the LOW BEAM position, the SJB sends voltage through circuit CLF04 (BN/BU) and circuit CLF05 (BU/GN) to the LH and RH High Intensity Discharge (HID) relay coils. When the relays are energized, voltage is routed to the LH and RH headlamps through circuit CLF30 (VT/BN) and circuit CLF31 (YE/GY).
B1472-B2498:
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- HID relay
- Headlamp switch
- SJB
PINPOINT TEST E: 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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E1 CHECK FOR AUTOLAMP DTCs
- Review the DTCs retrieved from the SJB self-test.
- Was DTC B1692 or B1791 retrieved?
Yes
REFER to Autolamps. Autolamps
No
GO to E2.
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E2 CHECK THE SJB HEADLAMP SWITCH PID
- Enter the following diagnostic mode on the scan tool: SJB DataLogger.
- Monitor the SJB headlamp switch PIDs while moving the headlamp switch through all positions. Refer to the following table.
- Do the headlamp switch positions agree with the PIDs?
Yes
GO to E7.
No
GO to E3.
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E3 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 E4.
No
INSTALL a new headlamp switch. REFER to Headlamp Switch Service and Repair. CLEAR the DTCs. REPEAT the self-test.
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E4 CHECK CIRCUIT GD116 (BK/VT) FOR AN OPEN
- Disconnect: Negative Battery Cable.
- Measure the resistance between the headlamp switch C205-1, circuit GD116 (BK/VT), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to E5.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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E5 CHECK THE HEADLAMP SWITCH INPUT CIRCUITS FOR A SHORT TO GROUND
- Disconnect: SJB C2280d.
- Measure the resistance between the headlamp switch, harness side and ground as follows:
- Are the resistances greater than 10,000 ohms?
Yes
GO to E6.
No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
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E6 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 E10.
No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
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E7 CHECK THE SJB OUTPUT
- Disconnect: SJB C2280a.
- Does the LH or RH headlamp continue to illuminate?
Yes
For halogen headlamps, REPAIR circuit CLF04 (BN/BU) (LH headlamp) or circuit CLF05 (BU/GN) (RH headlamp) as necessary. CLEAR the DTCs. REPEAT the self-test.
For HID headlamps, GO to E8.
No
GO to E10.
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E8 CHECK CIRCUIT CLF30 (VT/BN) (LH HEADLAMP) AND CIRCUIT CLF31 (YE/GY) (RH HEADLAMP) FOR A SHORT TO VOLTAGE
- Disconnect: Suspect HID Relay.
- Does the LH or RH headlamp continue to illuminate?
Yes
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
No
GO to E9.
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E9 CHECK THE HID RELAY
- Carry out the HID relay component test.
- Is the HID relay OK?
Yes
REPAIR circuit CLF04 (BN/BU) (LH HID relay) or circuit CLF05 (BU/GN) (RH HID relay) as necessary. CLEAR the DTCs. REPEAT the self-test.
No
INSTALL a new HID relay. CLEAR the DTCs. REPEAT the self-test.
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E10 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 Body Control Systems. 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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