A/C Control Mode Door Input Shorted To Ground (Manual A/C)
NOTE:
After making any repairs, perform BODY VERIFICATION TEST
under VERIFICATION TESTS.
Monitored & Set Condition
- When Monitored: With the ignition on.
- Set Condition: The BCM detects an abnormally low voltage on its mode request input.
Possible Causes:
- Control Head - Short To Ground
- Mode Switch MUX Circuit Shorted To Ground
- Body Control Module - Mode Switch MUX Shorted To Ground
Testing
- With the scan tool, erase BODY CONTROL DTC's. Turn ignition off. Disconnect the manual temp control head C1 harness connector. See Figure . Measure the resistance between ground and the mode switch MUX circuit. If the resistance is 100 ohms or less, go to next step. If the resistance is 100 ohms or less, replace the control head. See MANUAL A/C-HEATER SYSTEMS - CONCORDE & INTREPID article in HVAC.
- Disconnect BCM C2 harness connector. See Figure . Measure the resistance between ground and the mode switch MUX circuit. If the resistance is 100 ohms or less, repair the mode switch MUX circuit for a short to ground. If the resistance is 100 ohms or more, replace the BCM. See BODY CONTROL MODULE under REMOVAL & INSTALLATION.