GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2006 🢒 Canyon Pickup - 4WD 🢒 Transmission/Transaxle 🢒 Shift Lock Control 🢒 DTC B2708

Circuit Description

The body control module (BCM) controls the automatic transmission shift lock control solenoid by providing controlled voltage to the automatic transmission shift lock control solenoid. The BCM utilizes a smart driver to monitor the voltage and current flow of the automatic transmission shift lock control solenoid control circuit. DTC B2708 will set when the BCM detects a short to voltage when the automatic transmission shift lock control solenoid is inactive.

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 shift lock control solenoid is inactive.

Conditions for Setting the DTC

The BCM detects a short to voltage at the control circuit driver of the automatic transmission shift lock control solenoid for a minimum of 1 second.

Action Taken When the DTC Sets

The BCM disables shift lock control solenoid operation until the next key 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 voltage control circuit of the automatic transmission shift lock control solenoid is shorted to battery positive voltage, the shift lever will be locked in the PARK position.
    • 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 in Wiring Systems.

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 the control circuit of the automatic transmission shift lock control solenoid.

Step

Action

Yes

No

Schematic Reference: Shift Lock Control Schematics

Connector End View Reference: 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 output control 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

Test the control circuit of the automatic transmission shift lock control solenoid for a short to battery voltage.

Did you find and correct the condition?

Go to Step 6

Go to Step 4

4

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 6

Go to Step 5

5

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 6

--

6
  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