Pinpoint Test BM: The SELECTABLE Drive Mode Or Auto Hold Feature Is Inoperative, Cannot Be Enabled Or Disabled And Abs Module Communication Concern With ATCM

Normal Operation and Fault Conditions 

The selectable drive mode switch is part of the ATCM. When the drive mode switch is activated, the ATCM sends a message to the GWM over the HS-CAN2. The GWM relays the message to the ABS module over the FD-CAN. If the ABS module does not receive any messages within a certain time frame (usually less than 1 second) or if the message contains invalid information, the ABS module sets a DTC. For information on the all messages sent to the ABS module by the ATCM, REFER to: Anti-Lock Brake System (ABS) and Stability Control - System Operation and Component Description .

The auto hold switch is used to activate and deactivate the auto hold feature. The switch is an internal component of the ATCM. When the driver presses the auto hold switch, the ATCM sends an auto hold switch message to the GWM over the HS-CAN2. The GWM relays the message to the ABS module over the FD-CAN. The ABS module then waits for messages from the RCM and BCM as well as ABS sensor information to indicate the auto hold feature can be activated. Once all criteria has been met, the ABS module activates the auto hold feature.

DTC Fault Trigger Conditions 

Possible Sources 

• Network communication concern
• GWM
• ATCM