GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC B396A 01: Liftgate Motor Control Circuit Short to Battery

DTC B396A 02: Liftgate Motor Control Circuit Short to Ground

DTC B396A 04: Liftgate Motor Control Circuit Open

Diagnostic Fault Information

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Liftgate Module B+

B396A 02, B153A 08

B396A 02, B153A 08

--

--

Liftgate Position Sensor 5V Reference Voltage

2

B153E 08

2

--

Full Open Signal

B153B 02

2

2

--

Liftgate Disable Signal

1, 2

1

1

--

Liftgate Open Signal

1

1

1

--

Object Sensors Signal

B153F 05

B153F 05

B153F 07

--

Open/Close Switches Signal

B2494 02

1, 2

1, 2

--

Pawl Switch Signal

B153A 00

B153A 00

B153A 00

B153A 08

Position Sensor Signal 1

B153E 02

B153E 05, B153E 08

B153E 05

--

Position Sensor Signal 2

B153E 02

B153E 05, B153E 08

B153E 05

--

Ratchet Switch Signal

B153A 00

B153A 00

B153A 00

B153A 08

Sector Switch Signal

B153A 00

B153A 00

B153A 00

B153A 08

Disengage Clutch Control

B396B 02

B396B 04

B396B 01

--

Engage Clutch Control

B396B 02

B396B 04

B396B 01

--

Liftgate Latch Cinch Control

B2495 02

B2495 04

B2495 01

--

Liftgate Latch Release Control

B2495 02

B2495 04

B2495 01

--

Liftgate Motor Close Control

B396A 02

B396A 04

B396A 01

--

Liftgate Motor Open Control

B396A 02

B396A 04

B396A 01

--

Full Open Low Reference

--

2

2

--

Liftgate Switches Low Reference

--

1

1

--

Position Sensor Low Reference

--

B0153E 08

2

--

I/P Switch Ground

--

1

1

--

Liftgate Control Module Ground

--

2

2

--

1. Liftgate Switch Malfunction

2. Liftgate Malfunction

Circuit/System Description

The liftgate motor is a bi-directional motor and open or close operation is the result of the direction of the motor rotation. The liftgate control module (LGM) controls the liftgate motor through the control circuits by supplying power and ground in the appropriate polarity. The motor control circuits are monitored by the LGM prior to activation for a high or low condition and during motor operation for any irregular current flow conditions.

Conditions for Running the DTC

    • The system voltage is 9-18 volts.
    • Power open or close function is initiated.

Conditions for Setting the DTC

B396A 01

The LGM detects a short to voltage in the liftgate motor control circuits.

B396A 02

A loss of B+ voltage to the LGM or the LGM detects a short to ground in the liftgate motor control circuits.

B396A 04

The LGM detects an open/high resistance in the liftgate motor control circuits.

Action Taken When the DTC Sets

Power liftgate operation will be suspended.

Conditions for Clearing the DTC

    • The DTC will be current for as long as the fault is present.
    • When the fault is no longer present, the DTC will be a history DTC.
    • A history DTC will clear after 50 ignition cycles.

Diagnostic Aids

Important: Before testing can be performed the liftgate must be opened. Refer to Opening the Liftgate Without Electrical Power for the appropriate procedure.

Whenever the LGM loses power or is disconnected, the ignition must be cycled OFF then ON in order to reactivate the LGM.

In some circumstances high or low control circuit faults may cause the LGM to react as if the liftgate has encountered an object in its travel and reverse direction.

Reference Information

Schematic Reference

Liftgate Schematics

Connector End View Reference

Vehicle Access Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Output Controls
    •  Scan Tool Data List

Circuit/System Verification

  1. Ignition ON, doors unlocked, transaxle in Park, enable the power liftgate by pressing the liftgate enable/disable button on the I/P switch assembly.
  2. Open the liftgate by pressing the touchpad on the liftgate handle switch. The liftgate should release and power open.
  3. Close the liftgate by pressing the liftgate button switch. The liftgate should power close, cinch-in, and latch.

Circuit/System Testing

  1. Ignition OFF, disconnect the C2 harness connector at the LGM.
  2. Test for less than 1 ohm between the ground circuit terminal 6 and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 3 and ground.
  5. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, replace the LGM.
  6. Ignition OFF, connect the C2 harness connector and disconnect the C3 harness connector at the LGM.
  7. Test for less than 1 ohm between the control terminal 1 at the LGM and ground.
  8. If greater than the specified range, replace the LGM.
  9. Test for less than 1 ohm between the control terminal 2 at the LGM and ground.
  10. If greater than the specified range, replace the LGM
  11. Connect a test lamp between control terminal 1 and control terminal 2 at the LGM.
  12. Ignition ON, command the power liftgate to OPEN and CLOSE with a scan tool. The test lamp should illuminate when commanding the OPEN and CLOSE states.
  13. If the test lamp is always OFF during either of the commands, replace the LGM.
    If the test lamp is always ON, replace the LGM.
  14. If all circuits test normal, replace the liftgate motor assembly.

Component Testing

  1. Ignition OFF, disconnect the C3 harness connector at the liftgate module.
  2. Install a 15A fused jumper wire between the control circuit terminal 1 at the liftgate motor assembly and 12 volts. Momentarily install a jumper wire between the control circuit terminal 2 at the liftgate motor assembly and ground. The liftgate motor should perform the OPEN or CLOSE function.
  3. If the function does not perform as specified, replace the liftgate motor assembly.
  4. Reverse the jumper wires; the liftgate motor should perform the CLOSE or OPEN function.
  5. If the function does not perform as specified, replace the liftgate motor assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Liftgate Close Actuator Motor Replacement
    •  Control Module References for liftgate control module replacement, setup, and programming