Headlamp Switch Input Circuit High
HEADLAMP SWITCH INPUT CIRCUIT HIGHWHEN MONITORED
Ignition on.
SET CONDITION
The BCM detects a voltage greater than 4.75 V on the Headlamp Switch Input for more than 5 seconds.
POSSIBLE CAUSES
- Headlamp switch open
- Headlamp switch mux circuit open
- Headlamp switch return circuit open
- Body control module
DIAGNOSTIC TEST
1. INTERMITTENT CONDITION
Turn the ignition on.
With the Scan Tool, erase all BCM DTC's.
Turn the headlamps to the ON position.
With the Scan Tool, read DTCs.
Q: Does the Scan Tool display: HEADLAMP SWITCH INPUT CKT HIGH?
YES: Go To 2
NO: The condition is not present at this time. Monitor Scan Tool parameters while wiggling the related wire harness. Refer to any Technical Service Bulletins that may apply. Visually inspect the related wiring harness and connector terminals.
Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
2. HEADLAMP SWITCH OPEN
Turn the ignition off.
Disconnect the Multifunction Switch harness connector.
Connect a jumper wire between the Headlamp Switch MUX circuit and the Headlamp Switch Return circuit in the Multifunction Switch harness connector.
Turn the ignition on.
With the Scan Tool, select Body, Body Controller and read: Headlamp Switch volts.
Q: Does the Scan Tool display Headlamp Switch voltage below 0.5 volts?
YES: Replace the Headlamp Switch.
Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 3
3. HEADLAMP SWITCH MUX CIRCUIT OPEN
Turn the ignition off.
Disconnect the Body Control Module harness connector.
Disconnect the Multifunction Switch harness connector.
Measure resistance of the Headlamp Switch MUX circuit from the Body Control Module connector to the Multifunction Switch harness connector.
Q: Is the resistance above 5.0 ohms?
YES: Repair the Headlamp Switch MUX circuit for an open condition.
Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 4
4. HEADLAMP SWITCH RETURN CIRCUIT OPEN
Turn the ignition off.
Disconnect the Body Control Module harness connector.
Disconnect the Multifunction Switch C1 harness connector.
Measure resistance of the Headlamp Switch Return circuit from the Body Control Module connector to the Multifunction Switch harness connector.
Q: Is the resistance above 5.0 ohms?
YES: Repair the Headlamp Switch Return circuit for an open condition.
Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Replace the Body Control Module.
Perform BODY VERIFICATION TEST - VER 1. Body Verification Test