Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Flash to Pass | 2 | 1 | 1 | -- |
1. Flash to Pass Inoperative 2. Flash to Pass Always ON | ||||
Circuit/System Description
The flash to pass of the headlamp switch supplies a ground to the high beam headlamp circuit when applied. With the ground that is supplied by the flash to pass switch the high beam headlamps will stay ON as long as the switch is toggled.
Diagnostic Aids
An open/high resistance in the headlamp switch can cause the flash to pass inoperative.
Reference Information
Schematic Reference
Headlights/Daytime Running Lights (DRL) Schematics
Connector End View Reference
Lighting Systems Connector End Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Verification
Ignition ON, command the flash to pass ON and OFF with the headlamp switch. Observe the high beam headlamps. The headlamp high beams should turn ON and OFF with each commanded.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the headlamp switch.
- Ignition OFF, test for less than 1 ohm of resistance between the ground circuit and ground.
- Verify the headlamps are OFF.
- Install a 3-amp fused jumper wire between the signal circuit and ground. Verify the headlamps are ON.
- If all circuits test normal, test or replace the headlamp switch.
| ⇒ | If greater than 1 ohm, test the ground circuit for an open/high resistance. |
| ⇒ | If the headlamps are not OFF, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM. |
| ⇒ | If the headlamps are not ON, test the signal circuit of the headlamp switch for a short to voltage or an open/high resistance. If circuit tests normal, replace the BCM. |
Component Testing
- Ignition OFF, disconnect the harness connector at the headlamp switch.
- Test for infinite resistance between the signal terminal and the voltage supply terminal with the switch in the open position.
- Test for less than 1.5 ohms between the signal terminal and the high and low voltage supply terminals with the switch in the closed position.
| ⇒ | If less than infinite resistance, replace the headlamp switch. |
| ⇒ | If greater than 1.5 ohms, replace the headlamp switch. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
