Headlamp Sw Open Circuit

When Monitored: Ignition in RUN and IOD fuse/connector installed.

Set Condition: This DTC sets if the BCM detects voltage on the MUX circuit more than 4.8 volts.

Possible Causes are:

• HEADLAMP MUX VOLTS MORE THAN 4.9 VOLTS
• HEADLAMP SWITCH MUX OPEN
• HEADLAMP SWITCH RETURN OPEN
• BCM HEADLAMP MUX

1. Disconnect the left multi-function switch connector. Turn ignition on. Connect a jumper wire between headlamp switch MUX and headlamp switch return at the left multi-function switch. Using the DRBIII(R) in Body Sensors, read the Headlamp sw volts. Does the DRBIII(R) display HEADLAMP SWITCH 0.0 volts? If no, go to next step. If yes, replace the left multi-function switch. Perform BODY VERIFICATION TEST VER 1  under VERIFICATION TESTS.
2. Turn ignition off. Disconnect the left multi-function switch connector. Disconnect the Body Control Module C1 connector. Measure the resistance of the headlamp switch MUX circuit from the BCM C1 connector to the left multi-function switch connector. Is the resistance less than 5 ohms? If yes, go to next step. If no, repair the open headlamp switch MUX circuit. Perform BODY VERIFICATION TEST VER 1  under VERIFICATION TESTS.
3. Turn ignition off. Disconnect the left multi-function switch connector. Disconnect the Body Control Module C1 connector. Using an ohmmeter measure the Headlamp Switch Return circuit from BCM to left multi-function. Is the resistance less than 5 ohms? If yes, go to next step. If no, repair the open headlamp switch return circuit. Perform BODY VERIFICATION TEST VER 1  under VERIFICATION TESTS.
4. If there are no possible causes remaining, replace the Body Control Module. Perform BODY VERIFICATION TEST VER 1  under VERIFICATION TESTS.