Defog Switch Fault (MTC)

DEFOG SWITCH FAULT (MTC)

For a complete wiring diagram Consult Diagrams/Electrical

Theory of Operation

The Electronic Back Light (EBL) mode switch input changes when the switch is pushed down. A stored DTC indicates that the EBL mode switch was stuck in a pushed position for more than 10 minutes, but has since returned to its normal state. An active DTC indicates that the EBL mode switch is stuck in a pushed position. An active DTC will prevent proper EBL mode switch and status indicator function.

- When Monitored:
With the ignition on.

- Set Condition:
If the Electronic Back Light (EBL) mode switch stays in a pushed position for more than 10 minutes.





Diagnostic Test

1. VERIFY THAT THE DTC IS STILL ACTIVE
Turn the ignition on.
With the scan tool, erase HVAC DTCs.
Operate the EBL in the on and off positions several times.
Turn the ignition off, wait 10 seconds, then turn the ignition on. Wait 10 minutes before proceeding.
With the scan tool, read HVAC DTCs.
Does the scan tool display this DTC as active?

Yes

- Go To 2

No

- The condition that caused this symptom is currently not present. Check for an intermittent condition by inspecting the related wiring harness for chafed, pierced, pinched, and partially broken wires. Also, inspect the related connectors for broken, bent, pushed out, spread, corroded, or contaminated terminals. Repair as necessary.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

2. INSPECT FOR OBJECT OR SUBSTANCE CAUSING THE EBL MODE SWITCH TO STAY OR STICK IN A PUSHED POSITION
Inspect the A/C Heater Control for anything that would cause the EBL mode switch to stay or stick in a pushed position.
Is anything present that would cause the EBL mode switch to stay or stick in a pushed position?

Yes

- Repair as necessary.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Go To 3

3. CHECK FOR NORMAL EBL MODE SWITCH & STATUS INDICATOR FUNCTION
Press the EBL mode switch on and off several times while observing the EBL status indicator.
Does the EBL status indicator turn on and off?

Yes

- Go To 4

No

- Replace the A/C Heater Control.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

4. INSPECT THE A/C HEATER CONTROL FOR DAMAGE
Inspect the A/C Heater Control for damage.
Is the A/C Heater Control damaged?

Yes

- Replace the A/C Heater Control.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.

No

- Test Complete.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test.