Pinpoint Test A: Both Low Beams Are Inoperative

Headlamps

Pinpoint Tests

Pinpoint Test A: Both Low Beams Are Inoperative

Refer to Wiring Diagram Set 85, Headlamps for schematic and connector information. Diagrams By Number

Normal Operation

The Smart Junction Box (SJB) is supplied voltage for the low beams through circuit 1052 (TN/BK) from the Bussed Electrical Center (BEC). When a request for the low beams is detected, the SJB provides voltage to the low beams or High Intensity Discharge (HID) relays (if equipped). The headlamps share a common ground through circuit 1205 (BK).

This pinpoint test is intended to diagnose the following:

- Fuse
- Wiring, terminals or connectors
- BEC
- SJB



PINPOINT TEST A: BOTH LOW BEAMS ARE 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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A1 CHECK CIRCUIT 1052 (TN/BK) FOR A VOLTAGE


- Ignition OFF.
- Disconnect: SJB C2280h.
- Measure the voltage between the SJB C2280h-32, circuit 1052 (TN/BK), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
GO to A3.

No
VERIFY the BEC fuse 67 (30A) is OK. If OK, GO to A2. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short.

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A2 CHECK CIRCUIT 1052 (TN/BK) FOR AN OPEN


- Disconnect: BEC C1035a.
- Measure the resistance between the SJB C2280h-32, circuit 1052 (TN/BK), harness side and the BEC C1035a-A5, circuit 1052 (TN/BK), harness side.




- Is the resistance less than 5 ohms?

Yes
INSTALL a new BEC. TEST the system for normal operation.

No
REPAIR the circuit. TEST the system for normal operation.

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A3 CHECK CIRCUIT 1205 (BK) FOR AN OPEN


- Disconnect: BEC C1035c.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the BEC C1035c-E11, circuit 1205 (BK), harness side and ground.




- Is the resistance less than 5 ohms?

Yes
GO to A4.

No
REPAIR the circuit. TEST the system for normal operation.

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A4 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.

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