GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2005 🢒 Sunfire 🢒 DTC 🢒 DTC B2708

Circuit Description

The body control module (BCM) controls the automatic transmission shift lock control solenoid. Positive voltage is supplied via the ignition 1 voltage circuit to the automatic transmission shift lock control solenoid. The BCM controls the ground circuit of the automatic transmission shift lock control solenoid . When the brake pedal is depressed, the BCM removes the ground allowing the solenoid to disengage. This action allows the vehicle to be shifted out of the PARK position.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B2708 Gearshift Unlock Circuit High

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

Conditions for Setting the DTC

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

Action Taken When the DTC Sets

The BCM disables the automatic transmission (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 A/T shift lock control circuit is shorted to battery positive voltage, the automatic transmission shift lock control 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. Refer to Testing for Intermittent Conditions and Poor Connections

Test Description

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

  1. Listen for an audible click when the automatic transmission shift lock control solenoid operates. Command both the ON and OFF states. Repeat the commands as necessary.

    2.

  2. Tests for voltage at the ignition 1 voltage circuit of the automatic transmission shift lock control solenoid.

    3.

  3. Verifies that the BCM is providing a ground to the automatic transmission shift lock control solenoid.

    4.

  4. Tests if ground is constantly being applied to the automatic transmission shift lock control solenoid.

Step

Action

Yes

No

Schematic Reference: Shift Lock Control Schematics

Connector End View Reference: Shift Lock Control 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 - Vehicle in Vehicle DTC Information

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. With a scan tool, command the brake to shift relay ON and OFF.

Does the automatic transmission shift lock control 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 automatic transmission shift lock control solenoid.
  3. Turn ON the ignition, with the engine OFF.
  4. Probe the ignition 1 voltage circuit of the automatic transmission shift lock control 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. Turn OFF the ignition.
  2. Disconnect the automatic transmission shift lock control solenoid.
  3. Connect a test lamp between the automatic transmission (A/T) shift lock control circuit and the ignition 1 voltage circuit at the automatic transmission shift lock control solenoid connector .
  4. Turn ON the ignition, with the engine OFF.
  5. With a scan tool, command the brake to shift relay 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 A/T shift lock control circuit 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 A/T shift lock control circuit 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 harness connector of the automatic transmission shift lock control 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 (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

10

Repair the open in the ignition 1 voltage circuit of the automatic transmission shift lock control solenoid. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 13

--

11

Replace the automatic transmission shift lock control solenoid. Refer Transmission Control Replacement in Automatic Transaxle-4T40-E/4T45-E.

Did you complete the replacement?

Go to Step 13

--

12

Important: Perform the set-up procedure for the BCM.

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 as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK