GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Chevy K Silverado - 4WD 🢒 DTC 🢒 DTC B0414, B0424, or B3770

Circuit Description

The following DTCs are for the HVAC door actuators:

    • B0414 is for the left air temperature actuator.
    • B0424 is for the right air temperature actuator.
    • B3770 is for the mode actuator.

The HVAC control module controls the HVAC door actuators to regulate the airflow through the HVAC system. Each actuator consists of a stepper motor, a logic circuit, and a potentiometer. The potentiometer inside the door actuator allows the module to monitor the current position of the actuator drive shaft. The module supplies a 5-volt source voltage to the potentiometer on the 5-volt reference circuit. The module supplies ground to the potentiometer through the low reference circuit. The HVAC control module monitors the voltage drop across the potentiometer on the door position signal circuit. When the actuator shaft rotates, the voltage on the door position signal circuit changes. The module converts the voltage value to a count value where 1 volt is approximately equal to 51 counts.

The HVAC control module calibrates the travel range of the HVAC door actuators when it is initially powered by the battery positive voltage circuit. During calibration, the module commands the actuators in each direction until door travel is stopped. The module stores the minimum door positions and the maximum door positions of each actuator into memory. The total travel range is calculated by subtracting the minimum door position from the maximum door position. The door actuators can be calibrated again with a scan tool.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC B0414 Temperature Control 1 Feedback Circuit Range/Performance
    • DTC B0424 Temperature Control 2 Feedback Circuit Range/Performance
    • DTC B3770 Air Flow Control 6 Feedback Circuit

Conditions for Running the DTC
    • Battery voltage is 8.7-16.5 volts.
    • The ignition is ON.

Conditions for Setting the DTC

The DTC sets when one of the following conditions are present:

    • The actual door position value for the actuator is less than 5 counts.
    • The actual door position value for the actuator is greater than 250 counts.
    • The actuator fails calibration because the calculated travel range value is too great or too small.

Action Taken When the DTC Sets
    • If the DTC sets because the actual door position value is out of range, the HVAC control module will command the actuator to a default position.
    • If the DTC sets because the actuator failed a calibration, the HVAC control module will attempt to calibrate the motor in the next transition from OFF to RUN mode.

Conditions for Clearing the DTC
    • The DTC will become history if the HVAC control module no longer detects the condition that set the DTC.
    • The history DTC will clear after 100 fault-free ignition cycles.
    • The DTC can be cleared with a scan tool.

Diagnostic Aids
    • If the condition is not present refer to Testing for Intermittent Conditions and Poor Connections .
    • If the DTC sets following a calibration of the door actuator, inspect the door and the actuator for the following conditions:
       - A misaligned actuator
       - Broken linkages or binding linkages
       - A broken door or a binding door
       - An obstruction that prevents the door from operating within the full range of motion
       - Missing seals to the door
       - Poor connections at the harness connector of the door actuator
    • If a signal circuit of an actuator is short to ground and the resistance across the internal potentiometer is low, then this condition could cause a multiple DTC concern.

Test Description

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

  1. At least 2 of the DTCs must be set as current DTC to ensure correct diagnosis. If only one DTC is present then the answer is No.

    2.

  2. This step tests for the proper operation of the circuit in the low voltage range.

    3.

  3. This step tests for the proper operation of the circuit in the high voltage range. If the jumper fuse opens when you perform this test, the circuit is shorted to ground.

    4.

  4. This step tests for a short to voltage in the 5-volt reference circuit.

    5.

  5. This step tests for a high resistance or for an open in the low reference circuit.

    6.

  6. This step tests for an open on the low reference circuit that is common to all of the actuators. Choose the easiest HVAC door actuator that set a DTC to start the diagnosis.

    7.

  7. Disconnecting each actuator, one at a time, isolates the disconnected actuators signal circuit from the 5-volt reference circuit that is common to all the actuators.

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

2

Is DTC B1375 set as a current DTC?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle

Go to Step 3

3

With a scan tool, observe the Heating and Air Conditioning DTC list.

Does the scan tool indicate that at least 2 of the following DTC B0414, B0424, and B3770 are set as current DTC?

--

Go to Step 9

Go to Step 4

4
  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With the scan tool, observe the appropriate Door Actual parameter in the Heating and Air Conditioning data list.

Does the scan tool indicate that the appropriate Door Actual parameter is within the specified range?

5-250 counts

Go to Diagnostic Aids

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the appropriate HVAC door actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the appropriate Door Actual parameter.

Does the scan tool indicate that the appropriate Door Actual parameter is less than the specified value?

5 counts

Go to Step 6

Go to Step 16

6

  1. Turn OFF the ignition.
  2. Connect a 3-ampere fused jumper between the 5-volt reference circuit and the appropriate door position signal circuit of the HVAC door actuator.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the appropriate Door Actual parameter.

Does the scan tool indicate that the appropriate Door Actual parameter is greater than the specified value?

230 counts

Go to Step 7

Go to Step 14

7

  1. Disconnect the fused jumper.
  2. Measure the voltage between the 5-volt reference circuit and the low reference circuit of the HVAC door actuator.

Does the voltage measure less than the specified value?

5.5 V

Go to Step 8

Go to Step 13

8

  1. Turn OFF the ignition.
  2. Disconnect the negative battery cable.
  3. Measure the resistance from the low reference circuit of the HVAC door actuator to a good ground.

Does the resistance measure less than the specified value?

5 ohms

Go to Step 18

Go to Step 17

9

  1. Disconnect the most accessible affected HVAC door actuator.
  2. Probe the low reference circuit of the HVAC door actuator with a test lamp from battery positive voltage.

Does the test lamp illuminate?

--

Go to Step 10

Go to Step 17

10

  1. Turn ON the ignition, with the engine OFF.
  2. With a scan tool, observe the Heating and Air Conditioning DTC list.
  3. While observing DTC list, disconnect and connect the electrical connector for each affected HVAC door actuator.

Did the scan tool indicate that only one DTC was present when a HVAC door actuator was disconnected?

--

Go to Step 12

Go to Step 11

11

Test the 5-volt reference circuit of the appropriate HVAC door actuator for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 22

Go to Step 19

12

Test the appropriate door position signal circuit of the HVAC door actuator for a short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 22

Go to Step 18

13

Test the 5-volt reference circuit of the appropriate HVAC door actuator for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 22

Go to Step 19

14

Test the 5-volt reference circuit of the appropriate HVAC door actuator for a short to ground, for a high resistance, or for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 22

Go to Step 15

15

Test the appropriate door position signal circuit of the HVAC door actuator for a short to ground, for a high resistance, or for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 22

Go to Step 19

16

Test the appropriate door position signal circuit of the HVAC door actuator for a short to voltage. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 22

Go to Step 19

17
  1. Disconnect the HVAC control module.
  2. Test the low reference circuit of the appropriate HVAC door actuator for a high resistance or for an open. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 22

Go to Step 19

18

Inspect for poor connections at the harness connector of the appropriate HVAC door actuator. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

--

Go to Step 22

Go to Step 20

19

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 .

Did you find and correct the condition?

--

Go to Step 22

Go to Step 21

20

Important: Perform the calibration procedure for HVAC door actuators.

Replace the HVAC door actuator. Refer to the appropriate replacement procedure:

Did you complete the replacement?

--

Go to Step 22

--

21

Replace the HVAC control module. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

--

Go to Step 22

--

22
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle according to the Conditions for Running in the DTC, as specified in the supporting text.

Does the DTC set again?

--

Go to Step 4

System OK