B1340

CIRCUIT DESCRIPTION
The instrument panel integration module (IPM) commands left air temperature actuator movement with one of three voltage signals applied to the left air temperature door control circuit. A low voltage of 0 volts moves the left air temperature door toward full cold. 2.5 volts stops the actuator. 5 volts moves the left air temperature door toward full hot. The IPM determines the current position of the actuator by monitoring the feedback voltage of the left air temperature door position signal circuit. The feedback potentiometer position is a function of the actuator position. A high voltage indicates a full hot left air temperature door position. A low voltage indicates a full cold left air temperature door position. The IPM controls the left air temperature door position in order to maintain the selected air temperature on the HVAC control module.

Two separate faults can cause this DTC to set:
^ Whenever the IPMs keep alive memory battery power is interrupted, the IPM will perform a recalibration of the actuators. During recalibration, the IPM will drive the actuators to their minimum and maximum travel extremes. The IPM will then calculate a travel range from this data (max-min range) and compare it to a calibrated range within the IPM. If the actual travel range is not within the calibrated expected range, the actuator will be considered not calibrated and the DTC will set.
^ The IPM also performs a continuous test on the current feedback voltage. If the feedback voltage does not equal or fall within the calibrated limits, the DTC will set.

CONDITIONS FOR RUNNING THE DTC
^ The ignition is turned ON.
^ The IPMs keep alive memory (KAM) battery power must be interrupted to run the range check. This can be accomplished with the scan tool by commanding HVAC Recalibration in Heating and Air Conditioning Special Functions.

CONDITIONS FOR SETTING THE DTC
^ The IPM detects the left air temperature door position signal circuit is less than 0.25 volt (13 counts) or greater than 4.08 volts (208 counts).
^ The left air temperature actuators total travel range (max-mm) is less than or greater than the calibrated limits.

ACTION TAKEN WHEN THE DTC SETS
^ A default value of 2.50 volts (128 counts) will be substituted for the air temperature door position data by the IPM. The IPM will toggle the actuator between full hot and full cool in an attempt to maintain the selected air temperature on the HVAC control module.
^ Each time the ignition switch is turned ON, the IPM will recheck the actuator travel range.
^ The IPM will continue to make use of whatever travel range is still available.

CONDITIONS FOR CLEARING THE DTC
^ The DTC will become history if the IPM 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.

DIAGNOSTIC AIDS
^ The range fault can only be detected following a check of the actuator travel range. The actuator travel range check can only be initiated by disrupting power to the IPM.
^ The calibration limit is 152-250 counts (2.98-4.90 volts). An actual range below this limit suggests an obstruction or something stuck in the door limiting travel. An actual range above this limit suggests an over travel condition such as damaged or missing foam seals.
^ A damaged or broken air temperature door and or actuator can cause this DTC to set by allowing the actuator shaft to rotate unrestricted to its internal stop. The internal stops are outside of the feedback potentiometers 0-250 count working range.

TEST DESCRIPTION

Steps 1-8:

Steps 9-16:

Steps 17-23:

The numbers below refer to the step numbers on the diagnostic table.
6. Tests for the proper operation of the circuit in the high voltage range.
7. Tests for the proper operation of the circuit in the low voltage range. If the fuse in the jumper opens when you perform this test, the signal circuit is shorted to voltage.
8. Tests for a short to ground in the 5 volt reference circuit.