Pinpoint Test 4: The Headlamps Are On Continuously

PINPOINT TEST 4: THE HEADLAMPS ARE ON CONTINUOUSLY

Normal Operation

Low Beams

The smart junction box (SJB) sends reference signals to the headlight switch through circuits (W/V) (off), (L/GY) (parking lamps) and (Y/L) (headlamps). At any given time, the headlight switch routes one of the input circuits to ground through circuit (B/L).
When the SJB detects the headlight switch in the HEADLAMPS ON position with the multifunction switch in the LOW BEAM position, the SJB provides voltage through circuit (BR/L) to the LH low beam headlamp and circuit (L/G) to the RH low beam headlamp.

High Beams

The SJB sends a reference signal to the multifunction switch through circuits (GY/BR) (flash-to-pass) and (G/BR) (high beams). When the multifunction switch is placed in the FLASH-TO-PASS or HIGH BEAM position, the voltage signal is routed to ground. When the SJB detects a request for flash-to-pass or high beams (when the low beams are on), the SJB energizes the high beam relay (integrated into the SJB), which routes voltage through circuit (Y/V) to the high beam headlamps.

- DTC B1472 (Lamp Headlamp Input Circuit Short to Ground) - an on-demand DTC that sets when the SJB detects a short to ground from the headlamps on input circuit.
- DTC B1510 (Flash To Pass Switch Circuit Short to Ground) - an on-demand DTC that sets when the SJB detects a short to ground from the flash-to-pass request input circuit.
- DTC B2A22 (Headlamp Off Circuit Open) - an on-demand DTC that sets when the SJB detects an open from the headlight switch off input circuit.
- DTC B2A23 (High Beam Input Circuit Short to Ground) - an on-demand DTC that sets when the SJB detects a short to ground from the high beam request input circuit.
- DTC B2A2E (Right Front Lamp Low Beam Circuit Open) - an on-demand DTC that sets when the SJB detects a short to voltage from the RH low beam output circuit.
- DTC B2A30 (Left Front Lamp Low Beam Circuit Open) - an on-demand DTC that sets when the SJB detects a short to voltage from the LH low beam output circuit.

Possible Causes
- Wiring, terminals or connectors
- Headlight switch
- Multifunction switch
- SJB

Diagnostic Procedure

CAUTION: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. See Battery Disconnect.

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