Stop Start Button
The stop-start disable button is a momentary contact switch. It is normally open, CAN signal low. Closed (button being pushed) is CAN signal high. The Front Controls Interface Module reads the switch status and sends it over CAN to the PCM.
The PCM looks for a low to high transition to toggle the status of Stop-start from enabled (default state) to disabled. If there is another low to high transition, stop-start will go from disabled to enabled.
If the PCM stops receiving data from the FCIM, the PCM sets a U0256 - Lost Communication with Front Controls Interface Module "A".
If the FCIM detects that the switch is shorted to ground, it sets a B12CB -11 Start/Stop "Eco-Start" Enable Button Circuit Short To Ground. DTC sets if the button is pushed for 4 continuous seconds (8 samples) but will clear it if the fault is not detected any time after that for 500 msec
If the FCIM detects that the status indicator is shorted to ground, it sets a B12CA-11 - Start/Stop "Eco-Start" Status Indicator Circuit Short To Ground
If the FCIM detects that the status indicator is shorted to battery or open, it sets a B12CA-15 -Start/Stop "Eco-Start" Status Indicator Circuit Short To Battery or Open
If the button is stuck open, there are no low to high transitions. Since the PCM does not recognize a button push, stop-start will not be disabled if requested by the customer. All stop-start HMI will continue indicating that stop-start is enabled (e.g. Tell-Tale and IOD).
If the button is stuck closed, there are no low to high transitions. Since the PCM does not recognize a button push, stop-start will not be disabled if requested by the customer. All stop-start HMI will indicate that stop start is enabled (e.g. Tell-Tale and IOD).