Diagnostic Aids

The 12 volt start/stop system may be disabled for the following reasons:

• Disabled by driver using the Autostop switch
• Hood is ajar
• Brake vacuum is 45 kPa or less
• Battery state of charge too low
• Battery state of health too low
• Battery state of function too low
• Battery voltage is 12 V or less
• Idle boost is request
• A/C compressor is requested
• Relevant DTCs are set in the engine control module
• Coolant temperature is 120° C or greater
• Ambient air temperature and coolant temperature is too low
• Calculated battery temperature is less than 0° C or greater than 55° C
• Transmission is in gear (manual transmission)
• Clutch is released (manual transmission)
• Vehicle speed is 5 kph or greater
• If the Battery Sensor Module is not calibrated, the Autostop/Autostart system will be disabled. Some causes of the Battery Sensor Module being out of calibration include:
  • The battery was replaced
  • The battery negative cable was disconnected and reconnected
  • The battery was recharged while outside the vehicle
  • The battery was discharged while outside the vehicle
  • The battery was discharged while outside the vehicle
  • The battery was improperly charged:

    To properly charge the battery, the negative lead of the charger must be connected to chassis ground, NOT directly to the negative battery post. Connecting to chassis ground allows current to flow through the battery sensor module during charging and be measured. Connecting directly to the negative battery post charges the battery, but the current is not measured by the battery sensor module.

  • The Battery Sensor Module was not calibrated correctly
  • The Battery Sensor Module was disconnected and reconnected
  • No open circuit voltage read for 1 week