B3857

DTC B3857

CIRCUIT DESCRIPTION
The body control module (BCM) monitors the high beam headlamp signal circuit by verifying the high beam input.

CONDITIONS FOR RUNNING THE DTC
- Voltage supplied to the module is in the normal operating voltage range (approximately 10-16 volts).
- The high beam headlamps must be ON.

CONDITIONS FOR SETTING THE DTC
- The BCM detects a short to voltage, short to ground or an open in the high beam headlamp signal circuit.
- The condition must be present for more than 3 ms.

ACTION TAKEN WHEN THE DTC SETS
- The BCM stores DTC B3857 in memory.
- The SERVICE VEHICLE SOON telltale illuminates.

CONDITIONS FOR CLEARING THE DTC
- A current DTC B3857 will clear if the BCM no longer detects a short to battery voltage, short to ground or an open in the high beam headlamp signal circuit.
- A history DTC B3857 will clear after 100 consecutive ignition cycles if the condition for the malfunction is no longer present.
- A DTC B3857 will clear when commanded by a scan tool.

DIAGNOSTIC AIDS
- If the DTC B3857 is a history DTC, the fault may be intermittent.
- The following conditions may cause an intermittent malfunction to occur:
- An intermittent short to voltage in the high beam headlamp signal circuit.
- An intermittent short to ground in the high beam headlamp signal circuit.
- An intermittent open in the high beam headlamp signal circuit.
- An intermittent short to voltage in the BCM.

TEST DESCRIPTION

Steps 1-2:

Steps 3-7:

The numbers below refer to the step numbers on the diagnostic table.
2. Test for a short to battery positive voltage in the high beam headlamp signal circuit.
3. Test for a short to ground or an open in the high beam headlamp signal circuit.