GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2006 🢒 Terraza - 4WD 🢒 Brakes 🢒 Park Brake 🢒 DTC B2508 or B2509

Circuit Description

When the heated seat system is activated, the body control module (BCM) controls the heated seat operation through the heated seat relay control circuit and the heated seat relay. The relay energizes and applies battery positive voltage to the seat heater elements. The circuit that generated this DTC is the heated seat relay control circuit that is wired between the BCM and the heated seat relay.

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC B2508 Seat Heater Relay Circuit
    • DTC B2509 Seat Heater Relay Circuit

Conditions for Running the DTC
    • The BCM must be powered and cannot have B1327, Battery Voltage Low, as an active DTC for this DTC to set.
    • The BCM monitors the voltage of this circuit at all times, even when the ignition is in the OFF position.
    • The module voltage must be 9-16 volts.

Conditions for Setting the DTC
    • Open detected when the output is inactive.
    • Short to battery positive voltage detected when the output is inactive.
    • Short to ground detected when the output is inactive
    • Open in the ground circuit of the heated seat relay.

Action Taken When the DTC Sets

Current and history DTCs are stored.

Conditions for Clearing the DTC

The BCM will clear the current DTC when the short to ground, battery voltage, or open is no longer present.

Test Description

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

  1. During the heated seat relay operation, listen for an audible click from the relay. Repeat the commands, as necessary.

    2.

  2. This step verifies that the BCM is providing voltage to the heated seat relay.

    3.

  3. This step tests for an open in the ground circuit to the heated seat relay.

Step

Action

Yes

No

Schematic Reference: Driver Seat Schematics or Passenger Seat Schematics

Connector End View Reference: Power Seat Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehiclein Vehicle DTC Information

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, navigate to the appropriate Driver or Passenger Heated Seat output control screen by making the following selections:
    4. • Body control module (BCM)
    • Special functions
    • Output control
    • Miscellaneous tests
  4. Access the heated seat relay in order to verify operation.
  5. With a scan tool, command the appropriate Heated Seat ON and OFF.

Does the heated seat relay turn ON and OFF with each command?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Disconnect the heated seat relay.
  3. Turn ON the ignition, with the engine OFF.
  4. Connect a test lamp from the heated seat relay control circuit of the relay connector to ground.

Does the test lamp illuminate?

Go to Step 9

Go to Step 4

4

  1. Connect a test lamp between the heated seat relay control circuit of the relay connector to ground.
  2. With a scan tool, command the Heated Seat Relay ON and OFF.

Does the test lamp turn ON and OFF with each command?

Go to Step 5

Go to Step 6

5

  1. Connect a test lamp between the heated seat relay control circuit of the relay connector to the ground circuit of the relay of the relay connector.
  2. With a scan tool, command the Heated Seat Relay ON and OFF.

Does the test lamp turn ON and OFF with each command?

Go to Step 7

Go to Step 10

6

Test the heated seat relay control circuit of the heated seat relay for a short to ground or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 8

7

Inspect for poor connections at the harness connector of the heated seat relay. 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 13

Go to Step 11

8

Inspect for poor connections at the harness connector of the BCM. 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 13

Go to Step 12

9

Repair the short to battery positive voltage in the heated seat relay control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

--

10

Repair the open in the ground circuit of the heat seat relay. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

 

11

Replace the heated seat relay. Refer to Relay Replacement in Wiring Systems.

Did you complete the replacement?

Go to Step 13

--

12

Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 13

--

13
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

Go to Step 2

System OK