For 1990-2009 cars

### 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 Descriptor

DTC B153B 02: Liftgate Open Switch Signal Circuit Short to Ground
DTC B153B 05: Liftgate Open Switch Signal Circuit Open

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Liftgate Module B+ | B153A 08, B396A 02 | B153A 08, B396A 02 | -- | --
Liftgate Module B+ | U0230 00 | U0230 00 | -- | --
Liftgate Position Sensor 5V Reference Voltage | B153E 02 | B153E 08 | 2 | B1019 00
Full Open Signal | B153E 08 | B153B 05 | 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 08 | B153A 00 | B153A 08
Position Sensor Signal 1 | B153E 08 | B153E 08 | B153E 05 | --
Position Sensor Signal 2 | B153E 02 | B153A 08 | B153E 05 | B153E 08
Ratchet Switch Signal | B153A 00 | B153A 08 | 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 | B153E 08
Liftgate Motor Open Control | B396A 02 | B396A 04 | B396A 01 | B153E 08
Full Open Low Reference | -- | B153B 05 | 2 | --
Liftgate Switches Low Reference | -- | B153A 08 | 2 | B153E 08
Position Sensor Low Reference | -- | B153E 08 | 2 | --
I/P Switch Ground | -- | 1 | 1 | --
Liftgate Control Module Ground | -- | U0230 00 | 2 | --
1. Liftgate Switch Malfunction 2. Liftgate Malfunction

### Circuit/System Description

The full open switch is part of the gear motor assembly and will close and become active when the liftgate reaches the full open position. The full open switch signal circuit is supplied battery voltage through a resistor and monitored within the liftgate control module. The liftgate control module (LGM) provides a low reference circuit and when the switch contacts close, the signal circuit goes low and the LGM determines the switch to be active.

### Conditions for Running the DTC

• | The system voltage is 9-16 volts.

• | Power open or close operation is attempted.

### Conditions for Setting the DTC

The LGM detects a short to ground in the full open switch signal circuit.

### Action Taken When the DTC Sets

The power liftgate will not power close.

### 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.

### Reference Information

#### Schematic Reference

Liftgate Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Rear Hatch/Gate Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

Ignition ON, observe the scan tool LGM Full Open Switch parameter while opening and closing the liftgate. The parameter should change between Active and Inactive.

### Circuit/System Testing

1. Ignition OFF, disconnect the X3 harness connector at the LGM.
2. Ignition ON, verify the scan tool LGM Full Open Switch parameter is Inactive.

⇒ | If not the specified value, replace the LGM.

3. Liftgate OPEN, test for less than 1 ohm between the signal circuit terminal 5 and the ground circuit terminal 6.

⇒ | If greater than the specified range, replace the liftgate motor assembly.

4. Liftgate CLOSED, test for infinite resistance between the signal circuit terminal 5 and the ground circuit terminal 6.

⇒ | If less than the specified value, replace the liftgate motor assembly.

5. If all circuits test normal, replace the LGM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Liftgate Actuator Replacement

• | Control Module References for LGM replacement, setup and programming