GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2008 🢒 Optra 🢒 HVAC 🢒 HVAC - Automatic 🢒 DTC 4

Conditions for Setting the DTC

This code will set if the output of the mix door indicator indicates that the door opening angle is out of range or does not change value when the door should be moving. This would indicate a short circuit or an open in the sensor or the associated wiring harness, a door motor that is not operating, or a malfunction of the automatic temperature control (ATC) controller.

Step

Action

Value(s)

Yes

No

1
  1. Disconnect the instrument panel (I/P) wiring harness connector from the air mix door (AMD) motor.
  2. Use an ohmmeter to measure the resistance between terminals 5 and 7 or terminals 7 and 5 for diesel applications, on the AMD motor.

Does the measured resistance indicate an open or a shorted condition?

--

Go to Step 4

Go to Step 2

2

Measure the resistance between terminals 2 and 3 or terminals 3 and 2 for diesel applications, on the AMD motor.

Is the resistance measured equal to the specified value?

3000 ohms

Go to Step 3

Go to Step 4

3

Measure the resistance between terminals 6 and 2 or terminals 6 and 3 for diesel applications and between terminals 6 and 3 or terminals 6 and 2 for diesel applications, on the AMD motor.

Do these resistances add up to approximately the value measured between terminals 2 and 3 or terminals 3 and 2 for diesel applications?

3000 ohms

Go yo Step 5

Go to Step 4

4

Replace the AMD motor.

Did you complete the replacement?

--

System OK

--

5

Inspect the connector terminals at the AMD motor and the wiring in the ATC harness.

Is there a problem with any terminal on either the harness connector or the motor connector or the wiring?

--

Go to Step 6

Go to Step 7

6

Repair the problem found with a connector terminal or the wiring, or replace the motor as required.

Did you complete the repair or replacement?

--

System OK

--

7
  1. Remove the ATC controller from the instrument panel.
  2. Disconnect the harness connectors from the ATC controller.
  3. Inspect the connector terminals on the harness connectors and the controller connectors and the harness wiring.

Is there a problem with any of these connectors or the wiring?

--

Go to Step 8

Go to Step 9

8

Repair the problem found with a connector terminal or wiring.

Did you complete the repair?

--

System OK

--

9

Measure continuity in the harness between the controller connectors and the following AMD motor connectors:

    • Controller terminal A2 to motor terminal 7or 5 for diesel applications.
    • Controller terminal A8 to motor terminal 5 or 7 for diesel applications.
    • Controller terminal B6 to motor terminal 2 or 3 for diesel applications.
    • Controller terminal B5 to motor terminal 6
    • Controller terminal B4 to motor terminal 3 or 2 for diesel applications.

Does the continuity equal the specified value?

0 ohms

Go to Step 10

Go to Step 11

10

Repair the continuity problem.

Did you complete the repair?

--

System OK

--

11
  1. Connect the AMD motor to the ATC harness.
  2. Connect the ATC harness connectors to the controller.
  3. Turn the ignition to ON.
  4. Use backprobing for voltage measurements.
  5. Measure the voltage between ground and terminal B5 at the controller.

Is the voltage measured less than or equal to the specified value?

4 V

Go to Step 12

Go to Step 14

12
  1. Set the temperature controller to 18°C (64°F).
  2. Connect a voltmeter between ground and terminal A8 at the controller. It should display about 12 V.
  3. Raise the temperature setting on the controller to 32°C (90°F).

Does the voltage equal the specified value?

12 V to 0 V

Go to Step 13

Go to Step 15

13
  1. Connect a voltmeter between ground and terminal A2 at the controller. It should display about 12 V.
  2. Change the temperature setting to 18°C (64°F).

Does the voltage equal the specified value?

12 V to 0 V

Go to Step 20

Go to Step 15

14
  1. Inspect the wiring harness and the connector terminals associated with controller terminals B4, B5, and B6, and AMD motor terminals 2, 6, and 3 or 3, 6, and 2 for diesel applications.
  2. Repair any problem found.

Did you complete the repair?

--

System OK

--

15

Inspect all wiring circuits between the controller and the AMD motor.

Is there a problem in the wiring or the connectors?

--

Go to Step 16

Go to Step 17

16

Repair the condition in the wiring between the ATC controller and the AMD motor.

Did you complete the repair?

--

System OK

--

17

Inspect the AMD motor.

Is there a problem in the AMD motor?

--

Go to Step 18

Go to Step 19

18

Replace the AMD motor.

Did you complete the replacement?

--

System OK

--

19

Replace the controller.

Did you complete the replacement?

--

System OK

--

20

Observe the operation of the air mix door when the temperature setting is changed.

Does the door move normally?

--

Go to Step 22

Go to Step 21

21

Repair or replace the air mix door.

Did you complete the repair or replacement?

--

System OK

--

22

Observe the operation of the AMD motor when the temperature setting is changed.

Does the motor operate normally?

--

Go to Step 24

Go to Step 23

23

Replace the AMD motor.

Did you complete the replacement?

--

System OK

--

24

Connect everything and test the system.

Does DTC 4 reset?

--

Go to Step 25

System OK

25

Replace the controller.

Did you complete the replacement?

--

System OK

--