Pinpoint Test C: One Low Beam Headlamp Is Inoperative
Headlamps
Pinpoint Tests
Pinpoint Test C: One Low Beam Headlamp Is Inoperative
Refer to Wiring Diagram Set 85, Headlamps/Autolamps for schematic and connector information. Diagrams By Number
Normal Operation - Halogen Headlamps
When the Smart Junction Box (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. Ground is supplied on circuit GD121 (BK/YE) and circuit GD123 (BK/GY) for the LH and RH headlamps.
High Intensity Discharge (HID) Headlamps
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 HID relay coils. Ground for the HID relay coils is provided through circuit GD121 (BK/YE). Switched voltage for the LH and RH HID relays is provided from the Battery Junction Box (BJB) through circuit SBB26 (YE/RD) and circuit SBB27 (BU/RD). When the relays are energized, voltage is routed to the LH and RH headlamps through circuit CLF30 (VT/BN) and circuit CLF31 (YE/GY). Ground is supplied on circuit GD121 (BK/YE) and circuit GD123 (BK/GY) for the LH and RH headlamps.
- DTC B1795 (Lamp Headlamp Low Beam Circuit Open) - a continuous DTC that sets when the SJB detects an open from the LH or RH low beam output circuit.
- DTC B1797 (Lamp Headlamp Low Beam Circuit Short to Ground) - a continuous DTC that sets when the SJB detects a short to ground from the LH or RH low beam output circuit.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- HID relay
- HID bulb
- Headlamp assembly
- Ballast
- SJB
PINPOINT TEST C: ONE LOW BEAM HEADLAMP IS INOPERATIVE
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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C1 CHECK THE HEADLAMP GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Disconnect: Inoperative Headlamp.
- Measure the resistance between the LH headlamp C1021-1, circuit GD121 (BK/YE), harness side and ground; or between the RH headlamp C1041-1, circuit GD123 (BK/GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to C2.
No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
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C2 CHECK FOR VOLTAGE TO THE HEADLAMP
- Connect: Negative Battery Cable.
- Place the headlamp switch in the HEADLAMPS ON position.
- Measure the voltage between the inoperative headlamp, harness side and ground as follows:
- Is the voltage greater than 10 volts?
Yes
For HID headlamps, GO to C3.
For halogen headlamps, REPAIR or INSTALL a new headlamp assembly. REFER to Headlamp Assembly Service and Repair. CLEAR the DTCs. REPEAT the self-test.
No
For HID headlamps, GO to C5.
For halogen headlamps, GO to C10.
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C3 CHECK THE BALLAST
- Place the headlamp switch in the OFF position.
- Install a known good ballast.
- Place the headlamp switch in the HEADLAMPS ON position.
- Does the inoperative headlamp now illuminate?
Yes
REMOVE the known good ballast. INSTALL a new ballast. REFER to Ballast Service and Repair. CLEAR the DTCs. REPEAT the self-test.
No
REMOVE the known good ballast. GO to C4.
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C4 CHECK THE HID BULB
- Place the headlamp switch in the OFF position.
- Install the original ballast.
- Install a known good HID bulb.
- Place the headlamp switch in the HEADLAMPS ON position.
- Does the inoperative headlamp now illuminate?
Yes
INSTALL a new HID bulb. REFER to Headlamp Bulb - LH Headlamp Bulb - LH or Headlamp Bulb - RH Headlamp Bulb - RH. CLEAR the DTCs. REPEAT the self-test.
No
REPAIR or INSTALL a new headlamp assembly. REFER to Headlamp Assembly Service and Repair. CLEAR the DTCs. REPEAT the self-test.
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C5 CHECK CIRCUIT CLF04 (BN/BU) (LH HEADLAMP) OR CIRCUIT CLF05 (BU/GN) (RH HEADLAMP) FOR VOLTAGE
- Place the headlamp switch in the OFF position.
- Disconnect: Suspect HID Relay.
- Place the headlamp switch in the HEADLAMPS ON position.
- Measure the voltage between the LH HID relay pin 85, circuit CLF04 (BN/BU), BJB face side and ground; or between the RH HID relay pin 85, circuit CLF05 (BU/GN), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
TURN the headlamps off. GO to C7.
No
TURN the headlamps off. GO to C6.
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C6 CHECK CIRCUIT CLF04 (BN/BU) (LH HEADLAMP) OR CIRCUIT CLF05 (BU/GN) (RH HEADLAMP) FOR AN OPEN OR SHORT TO GROUND (HID HEADLAMPS)
- Disconnect: SJB C2280a.
- Measure the resistance between the suspect HID relay, BJB face side and the SJB, harness side; and between the suspect HID relay, BJB face side and ground as follows:
- Is the resistance less than 5 ohms between the HID relay and the SJB, and greater than 10,000 ohms between the HID relay and ground?
Yes
GO to C11.
No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
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C7 CHECK CIRCUIT SBB26 (YE/RD) (LH HID RELAY) OR CIRCUIT SBB27 (BU/RD) (RH HID RELAY) FOR VOLTAGE
- Measure the voltage between the LH HID relay pin 30, circuit SBB26 (YE/RD), BJB face side and ground; or between the RH HID relay pin 30, circuit SBB27 (BU/RD), BJB face side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to C8.
No
VERIFY the BJB fuse 26 (15A) (LH HID relay) or fuse 27 (15A) (RH HID relay) is OK. If OK, REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.
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C8 CHECK THE HID RELAY GROUND CIRCUIT FOR AN OPEN
- Disconnect: Negative Battery Cable.
- Measure the resistance between the LH HID relay pin 86, circuit GD121 (BK/YE), BJB face side and ground; or between the RH HID relay pin 86, circuit GD121 (BK/YE), BJB face side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to C9.
No
REPAIR circuit GD121 (BK/YE). CLEAR the DTCs. REPEAT the self-test.
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C9 CHECK THE HID RELAY
- Connect: Negative Battery Cable.
- Substitute a known good relay and recheck the headlamp operation.
- Does the headlamp in question operative correctly?
Yes
REMOVE the known good relay. INSTALL a new HID relay. CLEAR the DTCs. REPEAT the self-test.
No
REMOVE the known good relay. REPAIR circuit CLF30 (VT/BN) (LH HID relay) or circuit CLF31 (YE/GY) (RH HID relay) as necessary. CLEAR the DTCs. REPEAT the self-test.
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C10 CHECK CIRCUIT CLF04 (BN/BU) (LH HEADLAMP) OR CIRCUIT CLF05 (BU/GN) (RH HEADLAMP) FOR AN OPEN OR SHORT TO GROUND (HALOGEN HEADLAMPS)
- Disconnect: SJB C2280a.
- Measure the resistance between the inoperative headlamp, harness side and the SJB, harness side; and between the inoperative headlamp, harness side and ground as follows:
- Is the resistance less than 5 ohms between the headlamp and the SJB, and greater than 10,000 ohms between the headlamp and ground?
Yes
GO to C11.
No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the self-test.
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C11 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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