Circuit Description
The electronic actuator is driven by the heater and A/C control module to operate the air mix door. The position of the air mix door is adjusted in order to maintain the verified air-outlet temperature. A feedback potentiometer is used in the flat-pack motor so that the heater and A/C control module will know the position of the air mix door. A low voltage at CKT 733 (about 1.0 volt) represents a cold air valve position and a high voltage on CKT 733 (about 4.0 volts) represents a hot air valve position. The heater and A/C control module drives the electric actuator through CKT 1199 to the logic portion of the electric actuator by applying 0-2.5-5 volts through this circuit. Applying 5.0 volts on CKT 1199 to the logic portion of the electronic actuator will cause the air mix valve to move to the full cold position. Applying 0.0 volts on CKT 1199 to the logic portion of the electric actuator will cause the air mix door to move to the full hot position. Applying approximately 2.5 volts on CKT 1199 will cause the electric actuator to stop.
Conditions for Setting the DTC
With the ignition ON, the heater and A/C control module will detect DTC B0416 anytime that CKT 733 is near 5 volts or higher.
Action Taken When the DTC Sets
The heater and A/C control module will drive the temperature door to the full cold position if the system is in one of the following modes:
| • | UPPER OUTLET |
| • | BI-LEVEL |
| • | AUTO UPPER OUTLET/BI-LEVEL |
The heater and A/C control module will drive the temperature door to the full heat position if the system is in one of the following modes:
| • | LOWER |
| • | DEFOG |
| • | DEFROST |
| • | AUTO LOWER |
Conditions for Clearing the MIL/DTC
DTC B0416 will clear as soon as the fault goes away or has been repaired. The system will then return to normal operation. History DTCs can only be cleared by removing and restoring B+ or by using the scan tool.
Diagnostic Aids
| • | The heater and A/C control module may set class 2 lost communication DTCs when the BCM or the VCM is being reprogrammed. After reprogramming, inspect for DTCs in the heater and the A/C control module. Clear any history U DTCs then resume diagnostics. |
| • | Visually inspect the electric actuator and harness connector for loose or bent pins. If B+ has been removed from the heater and A/C control module and then restored for any reason, the heater and A/C control module system will (one time) drive the air mix door to full hot and then to full cold positions when power is restored. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This step inspects for a short to B+ on CKT 733 and CKT 1688.
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This step determines if a short to B+ is in the heater and A/C control module and wiring or the air mix electric actuator.
-
This step isolates the short to B+ to either the wiring or the heater and A/C control module.
-
This step repairs the short to B+ in CKT 1688 and CKT 733.
-
This step inspects for an open in CKT 733 and CKT 1688.
-
This step determines if the open is in CKT 733 and CKT 1688 or the heater and A/C control module.
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This step inspects for an open in CKT 1791.
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This step inspects for a defective electric actuator by temporarily installing a known good electric actuator.
-
This step replaces the defective electric actuator.
-
This step determines if the open is in CKT 1791 or in the heater and A/C control module.
-
This step replaces a defective heater and A/C control module.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 |
Is the reading as specified? | 9-16V | Go to Step 2 | Go to Step 5 |
2 |
Is the reading as specified? | 9-16V | Go to Step 3 | Go to Step 9 |
3 |
Is battery voltage present in any circuit? | -- | Go to Step 4 | Go to Step 11 |
4 | Repair the short to B+ in CKT 733 and CKT 1688. Is the repair complete? | -- | Go to Diagnostic System Check | -- |
5 |
Is the reading as specified? | 5V | Go to Step 7 | Go to Step 6 |
6 | Inspect CKT 733 and CKT 1688 for an open. Is the repair complete? | -- | Go to Diagnostic System Check | Go to Step 11 |
7 | Use a J 39200 in order to ground in order to inspect for continuity to ground at terminal 7 of the electric actuator harness connector. Is an open circuit indicated? | -- | Go to Step 10 | Go to Step 8 |
8 |
Does the test electric actuator function normally while changing temperatures? | -- | Go to Step 9 | Go to Step 11 |
9 | Replace the vehicle's air mix electric actuator. Refer to Temperature Actuator Replacement . Is the repair complete? | -- | Go to Diagnostic System Check | -- |
10 | Inspect CKT 1791 (YEL) including the heater and A/C control module for an open. Is the repair complete? | -- | Go to Diagnostic System Check | Go to Step 11 |
11 | Replace the heater and A/C control module. Is the repair complete? | -- | Go to Diagnostic System Check | -- |
