Pinpoint Test H: The Autolamps Are Inoperative

Autolamps

Pinpoint Tests

Pinpoint Test H: The Autolamps Are Inoperative

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

Normal Operation

The Smart Junction Box (SJB) sends a reference signal to the headlamp switch through circuit CLF19 (VT/GN) and a signal to the light sensor through circuit VLF14 (BU/BN). Ground for the light sensor is provided by circuit GD116 (BK/VT). When the headlamp switch is placed in the AUTOLAMPS ON position, the voltage signal is routed to ground. When the SJB detects the headlamp switch in the AUTOLAMPS ON position, the SJB sends out voltage to the exterior lamps if the ambient light conditions are dark. The light sensor determines the amount of light based on the input received from the ambient sky conditions. When the ambient level has reached a point (determined by the internal programming of the SJB), the SJB sends voltage to the headlamps, parking and license plate lamps.

- DTC B1793 (Autolamp Sensor Input Circuit Short to Ground) - a continuous DTC that sets when the SJB detects a short to ground from the light sensor input circuit.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- Light sensor
- SJB



PINPOINT TEST H: THE AUTOLAMPS ARE INOPERATIVE

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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H1 RETRIEVE THE RECORDED DTCs FROM THE SJB SELF-TEST


- Ignition OFF.
- Check the recorded results from the SJB self-test.
- Was DTC B1793 recorded?

Yes
GO to H3.

No
GO to H2.

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H2 CHECK THE MANUAL HEADLAMP OPERATION


- Place the headlamp switch in the HEADLAMPS ON position.
- Do the headlamps operate correctly?

Yes
GO to H3.

No
REFER to Headlamps. Headlamps

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H3 CHECK FOR VOLTAGE TO THE LIGHT SENSOR


- Disconnect: Light Sensor C286.
- Ignition ON.
- Place the headlamp switch in the AUTOLAMPS ON position.
- Measure the voltage between the light sensor C286-2, circuit VLF14 (BU/BN), harness side and ground.




- Is the voltage approximately 5 volts?

Yes
INSTALL a new light sensor. REFER to Light Sensor Service and Repair. CLEAR the DTCs. REPEAT the self-test.

No
GO to H4.

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H4 CHECK CIRCUIT VLF14 (BU/BN) FOR A SHORT TO GROUND


- Ignition OFF.
- Disconnect: SJB C2280d.
- Measure the resistance between the light sensor C286-2, circuit VLF14 (BU/BN), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to H5.

No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.

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H5 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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