3B Ignition MUX Switch Input Mismatch

3B-IGNITION MUX SWITCH INPUT MISMATCH





For a complete wiring diagram, refer to the Wiring Information Electrical Diagrams

- When Monitored:
There are two inputs to the BCM from the Ignition Switch. The high current Run/Start contact (non-MUX signal) of the ignition switch will make contact before the low current Run contact (MUX signal).

- Set Condition:
When the BCM detects the hardware Run/Start circuit is active while detecting the Ignition MUX circuit remains in the Lock/Acc/Unlock position for at least 2 seconds.





1. (G5) FUSED IGNITION SWITCH OUTPUT (RUN-START) SHORT TO VOLTAGE




1. Turn the ignition off.
2. Disconnect the BCM C4 harness connector.
3. Measure the voltage between the (G5) Fused Ignition Switch Output (Run-Start) circuit and ground.

Is there any voltage present?

Yes

- Repair the (G5) Fused Ignition Switch Output (Run-Start) circuit for a short to voltage.
- Perform the BODY VERIFICATION TEST. Body Verification Test

No

- Go To 2

2. (G5) FUSED IGNITION SWITCH OUTPUT (RUN-START) CIRCUIT OPEN




1. Turn the ignition off.
2. Disconnect the Ignition Switch harness connector.
3. Measure the resistance of the (G5) Fused Ignition Switch Output (Run-Start) circuit between the BCM C4 connector and the Ignition Switch connector.

Is the resistance above 5.0 ohms?

Yes

- Repair the (G5) Fused Ignition Switch Output (Run - Start) circuit for an open.
- Perform the BODY VERIFICATION TEST. Body Verification Test

No

- Go To 3

3. IGNITION SWITCH




1. Turn the ignition off.
2. Disconnect the BCM C2 harness connectors.
3. Measure the resistance of the Ignition Switch using the following values:
4. Key Out: 20140 - 22460 ohms
5. Key In: 7790 - 8810 ohms
6. Accessory: 3131 - 3564 ohms
7. Unlock: 1472 - 1764 ohms
8. Run: 539 - 767 ohms

Did the Ignition Switch resistance measure within specifications for each position?

Yes

- Replace and program the Body Control Module.
- Perform the BODY VERIFICATION TEST. Body Verification Test

No

- Replace the Ignition Switch.
- Perform the BODY VERIFICATION TEST. Body Verification Test