2007 Commander XK Factory Service Manual 24 - HEATING & AIR CONDITIONING

B106C-REAR DEFROST CONTROL CIRCUIT HIGH (ATC)





For a complete wiring diagram Refer to Section 8W.



Possible Causes
 
(C115) REAR WINDOW DEFOGGER RELAY CONTROL CIRCUIT SHORTED TO VOLTAGE
 
(C115) REAR WINDOW DEFOGGER RELAY CONTROL CIRCUIT OPEN
 
REAR WINDOW DEFOGGER RELAY
 
A/C HEATER CONTROL
 


NOTE: This DTC must be active for the results of this test to be valid. Do not perform this test if this DTC is stored. Refer to HVAC System Test (ATC) for stored DTC test procedures.



Diagnostic Test

1. INSTALL A SUBSTITUTE REAR WINDOW DEFOGGER RELAY & THEN CHECK FOR DTC B106C–REAR DEFROST CONTROL CIRCUIT HIGH



Turn the ignition on.
Verify that the EBL mode switch is off.
Turn the ignition off.
Install a substitute Rear Window Defogger Relay.
Turn the ignition on.
With the scan tool, erase HVAC DTCs.
Turn the ignition off, wait 10 seconds, and turn the ignition on.
Press the EBL mode switch is on.
With the scan tool, read HVAC DTCs.

Does the scan tool display: B106C–REAR DEFROST CONTROL CIRCUIT HIGH?

Yes


No

2. CHECK (C115) REAR WINDOW DEFOGGER RELAY CONTROL CIRCUIT FOR A SHORT TO VOLTAGE



Turn the ignition on.
Verify that the EBL mode switch is off.
Turn the ignition off.
Remove the substitute Rear Window Defogger Relay.
Disconnect the A/C Heater Control C1 harness connector.
Turn the ignition on.
Measure the voltage of the (C115) Rear Window Defogger Relay Control circuit.

Is the voltage above 0.2 volts?

Yes


No

3. CHECK (C115) REAR WINDOW DEFOGGER RELAY CONTROL CIRCUIT FOR AN OPEN



Turn the ignition off.
Measure the resistance of the (C115) Rear Window Defogger Relay Control circuit between the Rear Window Defogger Relay connector terminal 85 in the JB and the A/C Heater Control C1 harness connector.

Is the resistance below 5.0 ohms?

Yes


No