Electrical - Additional Battery Ground Information
NUMBER 015GROUP Electrical
DATE June 2011
MODEL All Model Equipped with Battery Sensor
SUBJECT: INSTALLATION OF ADDITIONAL BATTERY GROUND CABLE CAUTION
This bulletin provides information relating to vehicles equipped with a battery sensor. This bulletin is issued to emphasize not to install an additional ground cable to the battery on any vehicles equipped with a battery sensor. Installing an additional ground cable to a battery (-) terminal may cause the battery sensor to incorrectly recognize the battery state (charged/discharged) and temperature information. Therefore, please advise customers not to install an additional battery ground cable, and emphasize the fact that a vehicle repair caused by the additional battery around cable will not be covered under warranty.
Functions of the Battery Sensor
The battery sensor which is embedded on the battery (-) terminal transmits battery voltage and temperature information to the ECM. The ECM controls alternator voltage output necessary for the various vehicle electric units by duty cycle based on signals received from the battery sensor. Also, on some vehicles with the ISG (Idle Stop & Go) function, the Idle stop and auto start are determined by the battery SOC (State Of Charge) and SOH (State Of Health) information received from the battery sensor.
Potential problems when installing additional ground cables to the battery:
If an additional ground cable is installed on the battery (-) terminal, the battery sensor may incorrectly register that the battery is in a discharged state despite a normal battery condition. This may cause the battery sensor to transmit incorrect information to the ECM, alternator voltage output, and ISG control, resulting in improper operation of various systems and components, as well as possibly setting DTCs as shown below:
Service Procedure
Flow Chart