Pinpoint Test U: The Trail Control Feature Is Inoperative

Normal Operation and Fault Conditions
The IPC and message center are used to enable the trail control feature. When the driver enables the trail control feature, the IPC sends a trail control switch message to the GWM over the HS-CAN3 and the GWM relays this message to the ABS module over the FD-CAN. The ABS module adjusts the operating parameters of the anti-lock and stability control features, and aids in maintaining the set speed of the vehicle. Vehicle speed is adjusted using the cruise control steering wheel switches.

The driver door ajar message is sent from the BCM through the GWM and is used for trail control feature safety operation. When the trail control feature is enabled and active, and the driver door is opened, the IPC notifies the occupants through the message center and the driving torque propelling the vehicle is disabled. If descending an incline, the ABS maintains the descent speed until the vehicle is no longer on an incline. If ascending an incline, the vehicle rolls backward at a speed of 3 km/h (2 mph) until it is no longer on an incline.

Possible Causes
- Network communication concern
- Parking brake concern
- Cruise control concern
- IPC concern
- BCM concern
- PCM concern

U1 VERIFY CRUISE CONTROL OPERATION
- Test drive the vehicle to verify the cruise control system functions correctly.
Does the cruise control system operate correctly?

Yes GO to U2

No DIAGNOSE the cruise control system. REFER to: Cruise Control .

U2 VERIFY PARKING BRAKE OPERATION
- Operate the parking brake system and verify it operates correctly.
Does the parking brake system operate correctly?

Yes GO to U3

No DIAGNOSE the parking brake system. REFER to: Parking Brake .

U3 CHECK FOR DIAGNOSTIC TROUBLE CODES (DTCS) IN TRAIL CONTROL RELATED MODULES

Using a diagnostic scan tool, carry self tests on the following modules. Retrieve and record all Diagnostic Trouble Codes (DTCs).

IPC
BCM
PCMKOEO

Are there any Diagnostic Trouble Codes (DTCs) present in any of the modules listed above?

Yes

DIAGNOSE all Diagnostic Trouble Codes (DTCs). For IPC Diagnostic Trouble Codes (DTCs), REFER to: Instrumentation, Message Center and Warning Chimes . For BCM Diagnostic Trouble Codes (DTCs), REFER to: Body Control Module (BCM) . . For PCM Diagnostic Trouble Codes (DTCs), REFER to: Powertrain Control Module (PCM) Input and Output Controls .

GO to U4

U4 VERIFY ALL WIRING CONNECTIONS
- Ignition OFF.
- Disconnect IPC C220.
- Using a good light source, inspect all disconnected electrical connectors for the following:
  - Corrosion - install new connector or terminal and clean the module pins
  - Damaged or bent pins - install new terminals or pins
  - Pushed-out pins - install new pins as necessary
  - Spread terminals - install new terminals as necessary
Are the connectors free of corrosion, damaged pins, bent pins, pushed-out pins and spread terminals?

Yes GO to U5

No REPAIR the affected connectors or terminals. Refer to Connector Repair Procedures for schematic and connector information.

U5 CHECK FOR CORRECT IPC OPERATION

Connect IPC C220.

Operate the system and determine if the concern is still present.

Is the concern still present?

Yes	CHECK OASIS for any related service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no services articles address this concern, INSTALL a new IPC. REFER to: Instrument Panel Cluster (IPC) .

No	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. ADDRESS the root cause of any connector or pin issues.