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Home >> Buick >> 2007 >> Lucerne CX >> Repair and Diagnosis >> External Pages >> Different car >> Section 134 (HVAC Systems - Automatic) >> Diagnostic Information and Procedures >> DTC B0414, B0424, B3748 or B3749 >> Test Description

Test Description

WARNING: This page is about a different car, the 2006 Buick LaCrosse and 2006 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 2:  This step verifies that the HVAC control module is able to command the appropriate actuator through its full range of motion.
  2. 4:  If the actuator does not move at all, the problem is likely to be the drive circuitry within the HVAC control module, the actuator or the wiring harness. If the actuator does move, but not within its full range of motion, the problem is likely to be a mechanical binding of the actuator door or actuator door linkage.
  3. 6:  This step drives the actuator in one position. The actuator shaft will not move if the actuator door is already in the position you are attempting to drive it to.
  4. 7:  This step drives the actuator in the opposite direction.
DTC B0414, B0424, B3748 or B3749

Step Action Values Yes No
Schematic Reference: HVAC Schematics 
Connector End View Reference: HVAC Connector End Views 
1 Did you perform the Diagnostic System Check - Vehicle? - Go to Step 2  Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2 
  1. Install a scan tool.
  2. Turn the ignition ON, with the engine OFF.
  3. With the scan tool, command the appropriate actuator in both directions.
  4. Observe the appropriate Actual parameter.
Does the scan tool indicate that the value of the appropriate Actual parameter is within 5 counts or the minimum and maximum specified values?		 3 Counts
250 Counts		 Go to Diagnostic Aids Go to Step 3 
3 When commanding the actuator in both directions, does the scan tool indicate that the value of the appropriate Actual parameter changes by more than the specified value? 3 Counts Go to Step 7  Go to Step 4 
4  Test the appropriate door control A circuit and the appropriate door control B circuit for an open, high resistance, short to ground or a short to voltage. Refer to Circuit Testing andWiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 12  Go to Step 5 
5
  1. Turn the ignition OFF.
  2. Disconnect the HVAC control module.
  3. Connect a 10-amp fused jumper wire between the actuator door control A circuit of the appropriate actuator and battery positive voltage.
  4. Connect a 10-amp fused jumper wire between the actuator door control B circuit of the appropriate actuator and a good ground.
Does the actuator shaft rotate?		 - Go to Step 9  Go to Step 6 
6 
  1. Connect a 10-amp fused jumper wire between the actuator door control B circuit of the appropriate actuator and battery positive voltage.
  2. Connect a 10-amp fused jumper wire between the actuator door control A circuit of the appropriate actuator and a good ground.
Does the actuator shaft rotate?		 - Go to Step 9  Go to Step 7 
7  Inspect the appropriate door and actuator for the following conditions:
Did you find and correct the condition?		 - Go to Step 12  Go to Step 8 
8 Inspect for poor connections at the harness connector of the appropriate 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 12  Go to Step 10 
9 Inspect for poor connections at the harness connector of the HVAC control module. 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 12  Go to Step 11 
10
IMPORTANT: Perform the recalibration procedure for the appropriate actuator.
Replace the appropriate actuator. Refer to Mode Actuator Replacement , Air Temperature Actuator Replacement - Right , Air Temperature Actuator Replacement - Left  or Recirculation Actuator Replacement .Did you complete the replacement?		 - Go to Step 12  -
11 Replace the HVAC control module. Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming.
Did you complete the replacement?		 - Go to Step 12  -
12
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Does the DTC reset?		 - Go to Step 3  System OK
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