Diagnostic Aids
WARNING: This page is about a different car, the 2017 Cadillac ATS. However, it is still accessible from the selected car via links, so may be relevant.
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
- Minimum crank voltage is less than 8.7 V
- 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 recharged 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.
- Power on Reset is active when the parameters Battery Sensor Module Battery State Information and Battery Sensor Module Reset Occurred - Using Estimated State of Charge read Not Available (Not Learned) and Yes (Estimated). Stop/start is enabled when Power on Reset is active.
- Vehicle has not been allowed to sit for at least 3 hours over 1 week.
- No open circuit voltage read for 1 week
- Parasitic current draw 100 mA or greater
- When using a vehicle hoist to verify autostop and autostart operation, ensure the following conditions are also met:
- Transmission gear selector is in the drive position
- No DTCs are set
- Traction control is off