• | 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. |
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 | B153B 08 | 2 | B1019 00 |
Full Open Signal | B153E 08 | B153B 05 | 2 | -- |
Object Sensors Signal | B153F 02 | B153F 05 | B153F 05 | B153F 03, 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 08 | 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 | 1 | B153E 08 |
Position Sensor Low Reference | -- | B153E 08 | 2 | -- |
Liftgate Control Module Ground | -- | U0230 00 | 2 | -- |
1. Liftgate Switch Malfunction 2. Liftgate Malfunction |
The liftgate module (LGM) controls operation of the liftgate latch motor and the liftgate actuator assembly. Under normal conditions the power latch can only be unlatched under power from the LGM through an input from the liftgate handle switch or the remote keyless entry (RKE) transmitter, but the liftgate may be manually closed to the primary latched position without the LGM performing the power latch function. The liftgate actuator assembly consists of an actuator drive motor that contains 2 internal hall effect sensors. The drive motor is mated to a gear that is connected to an actuator clutch. When the clutch is engaged the motor rotation is transferred to the clutch gear, intermediate gear, and actuator arm gear. The full open switch is a limit switch mounted on the liftgate actuator assembly along side the actuator arm gear, and will make contact with the cam on the actuator arm gear when the liftgate is near the full open position. The LGM continuously monitors the liftgate location and direction of travel using the 2 hall effect sensors located in the drive motor assembly. The sensors are used to determine when the liftgate has reached the full open and full closed points of travel where the actuator clutch should be disengaged. These positions may vary slightly and must be learned when most liftgate components are serviced.
Power liftgate function will only be allowed if certain operating criteria are met. Any of the following may cause the power liftgate not to function:
• | After a power loss of the low current battery supply until the ignition is cycled |
• | Vehicle is not in park. |
• | Engine cranking is present. |
• | Ambient temperature at the LGM must be within -17 to +80°C (+1 to +176°F). |
• | Liftgate motor excess current is detected. |
• | System voltage is out of range. |
• | A DTC is set that disables power liftgate functionality. |
• | The liftgate is locked when attempting to open from exterior handle. |
The LGM also receives input from 2 pressure sensing object detection sensors. If either of these sensors indicates an object may be pinched as the liftgate is brought to the closed position, the liftgate will reverse direction and power close operation will be suspended until the pressure against the sensor is released.
Whenever the LGM loses power or is disconnected, the ignition must be cycled OFF then ON in order to reactivate the LGM.
Certain SIR DTC's will make the power liftgate inoperative. Correct any SIR concern first before performing any extensive power liftgate diagnostics.
Liftgate Description and Operation
Control Module References for scan tool information
⇒ | If the parameter does not change, refer to Liftgate Handle Switch Inoperative. |
⇒ | If the liftgate will not remain open, replace the liftgate struts. |
⇒ | If the liftgate fails to OPEN, refer to Power Liftgate Inoperative. |
⇒ | If the liftgate closes and immediately reopens, refer to Liftgate Closes and Reopens. |
⇒ | If not the specified value, test the signal circuit terminal listed below for a short to ground. If the circuit tests normal, replace the LGM. |
• | Liftgate close switch signal circuit terminal 1 |
• | Liftgate handle switch signal circuit terminal A |
• | Liftgate close switch signal circuit terminal 2 |
• | Liftgate handle switch signal circuit terminal A |
⇒ | If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the LGM. |
⇒ | If the parameter does not change, test or replace the liftgate handle switch. |
⇒ | If not the specified value, test the signal circuit terminal 5 for a short to ground. If the circuit tests normal, replace the LGM. |
⇒ | If not the specified value, test the signal circuit terminal 4 for a short to ground. If the circuit tests normal, replace the LGM. |
Important: Check the alignment of the liftgate striker, if the liftgate striker is adjusted too far inboard it could allow the LGM to detect an excess motor current condition and reverse the motor.
⇒ | If less than the specified value, test the signal circuit for a short to ground. |
⇒ | If not within the specified range, test the signal circuit between the left and right liftgate object sensors and the low reference circuit for an open/high resistance. If the circuits test normal, test or replace the left or right liftgate object sensor. |
⇒ | If less than the specified value, replace the liftgate handle switch. |
⇒ | If greater than the specified range, replace the liftgate handle switch. |
⇒ | If less than the specified value, replace the liftgate close switch. |
⇒ | If greater than the specified range, replace the liftgate close switch. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for LGM replacement, setup, and programming |