GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 2001 🢒 Aurora 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 DTC B0490

Circuit Description

The right air temperature switch assembly is a variable resistor. The front passenger door module (FPDM) determines the position of the temperature switch based on the voltage from the variable resistor. When a cooler temperature is selected, the voltage increases. When a warmer temperature is selected, the voltage decreases. The FPDM converts this input to a digital signal and communicates it to the driver door module (DDM) over the power door serial data circuit. The DDM is responsible for the class 2 interface and setting the DTC.

Conditions for Running the DTC

The ignition is turned ON.

Conditions for Setting the DTC

The DDM detects that the right air temperature switch signal circuit of the right air temperature switch assembly is less than 0.09 V (5 counts) or greater than 4.90 V (250 counts).

Action Taken When the DTC Sets

The DDM will ignore the switch command.

Conditions for Clearing the DTC
    • The DTC will become history if the DDM 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.

Diagnostic Aids

Switch Position

Counts

COOL

183

COOL

178

COOL

164

NEUTRAL

144

WARM

113

WARM

60

WARM

13

Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Test Description

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

  1. The value given is the normal condition that exists when the switch is in the neutral position.

    2.

  2. Tests for the proper operation of the circuit in the high voltage range.

    3.

  3. 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.

Step

Action

Values

Yes

No

Schematic Reference: HVAC Schematics

1

Did you perform the HVAC Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - HVAC Systems - Automatic

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Place the right air temperature switch assembly in the neutral position.
  4. With a scan tool, observe the Pass. HVAC Switch parameter in the Driver Door Module data list.

Does the scan tool indicate that the Pass. HVAC Switch parameter is near the specified value?

143 counts

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the right air temperature switch assembly.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Pass. HVAC Switch parameter.

Does the scan tool indicate that the Pass. HVAC Switch parameter is greater than the specified value?

250 counts

Go to Step 4

Go to Step 5

4

  1. Turn OFF the ignition.
  2. Connect a 3-amp fused jumper wire between the right air temperature switch signal circuit and the low reference circuit of the right air temperature switch assembly.
  3. Turn ON the ignition, with the engine OFF.
  4. With a scan tool, observe the Pass. HVAC Switch parameter.

Does the scan tool indicate that the Pass. HVAC Switch parameter is less than the specified value?

5 counts

Go to Step 8

Go to Step 6

5

Test the right air temperature switch signal circuit of the right air temperature switch assembly 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 12

Go to Step 9

6

Test the right air temperature switch signal circuit of the right air temperature switch assembly 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 12

Go to Step 7

7

Test the low reference circuit of the right air temperature switch assembly 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 12

Go to Step 9

8

Inspect for poor connections at the harness connector of the right air temperature switch assembly. 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 front passenger door 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

Replace the right air temperature switch assembly. Refer to Air Temperature Switch Assembly Replacement - Right Side .

Did you complete the replacement?

--

Go to Step 12

--

11

Replace the front passenger door module. Refer to Door Control Module Replacement in Doors.

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 2

System OK