B1020

Schematic Reference HVAC Air Delivery/Temperature Control Schematics

Steps 1-3:

CIRCUIT DESCRIPTION
This DTC is intended to be an indication of a problem for which the Rear Auxiliary ECC module must be replaced. Due strictly to malfunctions internal to the Rear Auxiliary ECC module which the service technician cannot troubleshoot by looking at external sensors, or other modules.

CONDITIONS FOR RUNNING THE DTC
The ignition is turned ON.

CONDITIONS FOR SETTING THE DTC
- This test checks the value of the Infrared thermistor (part of the Rear Aux ECC module) and the stored thermistor values. If the stored values are above or below the system specifications, the DTC will be set.
- The above conditions are present for 3 consecutive failures.

ACTION TAKEN WHEN THE DTC SETS
- The automatic portion of the heater and A/C system will be disabled.
- A calibrated (failsoft) value will be used in all HVAC calculations requiring the rear system air temperature to be approx. 75°F.

CONDITIONS FOR CLEARING THE DTC
- The DTC will become history if the HVAC Module no longer detects a failure.
- The history DTC will clear after 50 fault free ignition cycles.
- The DTC can be cleared with a scan tool.