GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2000 🢒 Sunfire 🢒 DTC 🢒 DTC B2708 Gearshift Unlock Circuit High

Object Number: 491249 Size: MF
Power Distribution Schematics

Circuit Description

The body control module (BCM) controls the A/T shift lock control solenoid. Positive voltage is supplied through the ERLS fuse through circuit 439 to terminal B of the A/T shift lock control solenoid. The BCM supplies a ground signal to the solenoid through circuit 323 to terminal A of the solenoid. When the brake pedal is depressed, the BCM removes the ground signal allowing the solenoid to disengage. This action allows the vehicle to be shifted out of park.

Conditions for Running the DTC
    • The ignition switch is in the on position.
    • The brake pedal is depressed.

Conditions for Setting the DTC

The shift lock control circuit is shorted to battery positive voltage for 1 second.

Action Taken When the DTC Sets

The BCM disables the A/T shift lock control output for the remainder of the ignition cycle.

Conditions for Clearing the DTC
    • A current DTC B2708 will clear when the malfunction is no longer present and the ignition switch is cycled.
    • All BCM history codes will clear after 100 ignition cycles with no current codes active during the 100 ignition cycles.

Diagnostic Aids
    • If the shift lock control circuit is shorted to battery positive voltage, the A/T shift lock solenoid will be inoperative. The vehicle will shift out of park without depressing the brake pedal.
    • Perform the tests while wiggling the wires and connectors. This may often cause an intermittent malfunction to appear.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

  1. Listen for an audible click when the A/T shift lock solenoid operates. Command both the ON and OFF states. Repeat the commands as necessary.

    2.

  2. Tests for voltage at the coil side of the A/T shift lock solenoid. The ERLS fuse supplies power to the coil side of the A/T shift lock solenoid.

    3.

  3. Verifies that the body control module is providing ground to the A/T shift lock solenoid.

    4.

  4. Tests if ground is constantly being applied to the A/T shift lock solenoid.

Step

Action

Yes

No

1

Did you perform the Body Control System Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Body Control System

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the A/T shift lock solenoid ON and OFF.

Does the A/T shift lock solenoid 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 A/T shift lock solenoid.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the coil side feed circuit of the A/T shift lock solenoid with a test lamp that is connected to a good ground.

Does the test lamp illuminate?

Go to Step 4

Go to Step 10

4

  1. Connect a test lamp between the control circuit of the A/T shift lock solenoid and the coil side feed circuit of the A/T shift lock solenoid.
  2. With a scan tool, command the A/T shift lock solenoid ON and OFF .

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

Go to Step 8

Go to Step 5

5

Does the test lamp remain illuminated with each command?

Go to Step 7

Go to Step 6

6

Test the control circuit of the A/T shift lock solenoid for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 13

Go to Step 9

7

Test the control circuit of the A/T shift lock solenoid 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 13

Go to Step 9

8

Inspect for poor connections at the A/T shift lock solenoid. 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

9

Inspect for poor connections at the harness connector of the body 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 13

Go to Step 12

10

Repair the coil side feed circuit of the A/T shift lock solenoid. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

--

11

Replace the A/T shift lock solenoid.

Did you complete the replacement?

Go to Step 13

--

12

Replace the body control module. Refer to Body Control Module Replacement in Body Control System.

Important: Perform the set up procedure for the body control module. Refer to Body Control Module (BCM) Programming/RPO Configuration .

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 as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK