The following DTCs are for the HVAC door actuators:
• | B1340 -left air temperature actuator |
• | B1341- right air temperature actuator |
• | B1343 -recirculation actuator |
• | B1344 - mode actuator |
The instrument panel module (IPM) controls the HVAC door actuators to regulate the airflow through the HVAC system. Each actuator is a 5 wire bi-directional electric motor that incorporates a feedback potentiometer. Ignition 3 voltage, low reference, control, 5 volt reference and position signal circuits enable the actuator to operate. The control circuit uses either a 0, 2.5 or 5 volt signal to command the actuator movement. When the actuator is at rest, the control circuit value is 2.5 volts. A 0 or 5 volt control signal commands the actuator movement in opposite directions. When the actuator shaft rotates, the potentiometer's adjustable contact changes the door position signal between 0-5 volts. The IPM converts the voltage values to count values where 1 volt is approximately equal to 51 counts. The IPM uses a range of 0-255 counts to index the actuator position. The door position signal voltage is converted to a 0-255 count range. When the module sets a commanded, or targeted value, the control signal is changed to either 0 or 5 volts depending upon the direction that the actuator needs to rotate to reach the commanded value. As the actuator shaft rotates the changing position signal is sent to the module. Once the position signal and the commanded value are the same, the module changes the control signal to 2.5 volts.
• | 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. |
• | Left air temperature actuator |
- | The IPM detects the position signal circuit is less than 0.25 volt (13 counts) or more than 4.08 volts (208 counts). |
- | The actuators total travel range, max-min is less than or more than the calibrated limits. |
• | Right air temperature actuator |
- | The IPM detects the position signal circuit is less than 0.88 volt (45 counts) or more than 4.35 volts (222 counts). |
- | The actuators total travel range, max-min is less than or more than the calibrated limits. |
• | Mode actuator |
The actuators total travel range, max-min is less than or more than the calibrated limits. |
• | Recirculation actuator |
- | The IPM detects the position signal circuit is less than 0.25 volt (13 counts) or more than 4.80 volts (245 counts). |
- | The actuators total travel range, max-min is less than or more than the calibrated limits. |
• | A default value will be substituted for the door position data by the IPM. |
• | 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. |
• | 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. |
• | If the condition is not present refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
• | 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. |
• | An actual range below this limit suggest 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 seal. |
• | A damaged or broken door an or actuator can cause the DTC to set by allowing the actuator shaft to rotate unrestricted to its internal stop. The internal stops are outside of the working range of the feedback potentiometers 0-250 counts. |
• | Left air temperature actuator |
The calibration limit is 152-250 counts. |
• | Right air temperature actuator |
The calibration limit is 130-250 counts. |
• | Recirculation actuator |
The calibration limit is 165-195 counts. |
• | Mode actuator |
The calibration limit is 215-245 counts. |
The numbers below refer to the step numbers on the diagnostic table.
Tests for the HVAC actuator operating within its travel range.
Test the actual travel range of the HVAC actuator.
Tests the HVAC actuator for proper operation.
Tests for the proper operation of the circuit in the high voltage range.
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.
Tests for a short in the 5 volt reference circuit.
Tests the HVAC actuator door position signal circuit for a short to ground.
Tests the HVAC actuator door position signal circuit for a short to voltage, high resistance, or an open.
Tests the HVAC actuator low reference circuit for high resistance or an open.
Tests the HVAC actuator ignition 3 voltage circuit for high resistance or an open.
Tests the HVAC actuator door control circuit for an open, high resistance, or a short to ground.
Test for an inoperative HVAC actuator.
Tests for proper operation of the IPM.
Step | Action | Values | Yes | No | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: HVAC Schematics Connector End View Reference: HVAC Connector End Views | ||||||||||||||||
1 | Did you perform the HVAC Diagnostic System Check? | -- | Go to Step 2 | |||||||||||||
Does the scan tool indicate that the Dr. Actual parameter is within the specified range? |
| Go to Step 3 | Go to Step 4 | |||||||||||||
Does the result of the calculation indicate that the actual travel of the actuator is within the specified range? |
| Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 14 | |||||||||||||
Does the scan tool indicate that the appropriate Dr. Actual parameter changes when the appropriate Door Position is commanded? | -- | Go to Step 5 | Go to Step 6 | |||||||||||||
5 | Inspect the appropriate HVAC door for a condition allowing excessive travel of the actuator. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 6 | ||||||||||||
Does the scan tool indicate that the Dr. Actual parameter is more than the specified value? |
| Go to Step 7 | Go to Step 11 | |||||||||||||
Does the scan tool indicate that the Dr. Actual parameter is less than the specified value? |
| Go to Step 8 | Go to Step 12 | |||||||||||||
Does the scan tool indicate that the Dr. Actual parameter is more than the specified value? |
| Go to Step 10 | Go to Step 9 | |||||||||||||
9 | Test the 5-volt reference circuit of the appropriate HVAC actuator for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 12 | ||||||||||||
10 | Test the 5-volt reference circuit for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 11 | ||||||||||||
Test the door position signal circuit of the appropriate HVAC actuator for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 12 | |||||||||||||
Test the door position signal circuit of the appropriate HVAC actuator for a short to voltage, a high resistance, or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 13 | |||||||||||||
Test the low reference circuit of the appropriate HVAC actuator for a high resistance or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 20 | |||||||||||||
Test the ignition 3 voltage circuit of the appropriate HVAC actuator for an open or a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 15 | |||||||||||||
Test the door control circuit of the appropriate HVAC actuator for an open, high resistance, short to ground or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 16 | |||||||||||||
Important: Ensure that the appropriate HVAC actuator connector and the IPM connector are connected during this step in order to avoid misdiagnosis.
Does the actuator drive shaft rotate and do the counts change? | -- | Go to Step 17 | Go to Step 19 | |||||||||||||
Does the voltage measure near the specified value for each commanded state? | 0 V 5 V 2.5 V stationary | Go to Step 18 | Go to Step 20 | |||||||||||||
18 | Inspect the appropriate HVAC door and the actuator for the following conditions:
Did you find and correct the condition? | -- | Go to Step 23 | Go to Diagnostic Aids | ||||||||||||
19 | Inspect for poor connections at the harness connector of the appropriate HVAC actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 21 | ||||||||||||
20 | Inspect for poor connections at the harness connector of the IPM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 23 | Go to Step 22 | ||||||||||||
21 |
Important: : Perform the recalibration procedure for the HVAC door actuators. Replace the HVAC door actuator. Refer to the appropriate replacement procedure: Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||||||||
22 |
Important: : Perform the recalibration procedure for the IPM module. Replace the IPM. Refer to Instrument Panel Module Replacement in Body Control System. Did you complete the replacement? | -- | Go to Step 23 | -- | ||||||||||||
23 |
Does the DTC reset? | -- | Go to Step 2 | System OK |