Battery Temperature Sensor Circuit
The PCM has detected an abnormal voltage reading from the battery temperature sensor circuit.
Code Set Parameters
Battery temperature readings that fluctuate from ambient temperature by more than a predetermined tolerance level will cause a code to be stored and a malfunction indicator lamp to be illuminated.
Symptoms are typically limited to only service engine soon lamp illumination and a stored trouble code.
Technicians report that faulty battery temperature sensors are fairly common when this code is exhibited. Open or shorted electrical wiring and/or connectors have also proven to be common causes. Engine overheating can contribute to this code being stored as well. Excessive battery corrosion may also prove detrimental to the battery temperature sensor.
Battery replacement is a common misdiagnosis when this code is presented.
- Battery temperature sensor input data is used by the PCM (in conjunction with charging system voltage data) to regulate the rate in which the alternator charges the battery
- The battery temperature sensor is usually located in the battery tray, underneath the battery
- Often it is part of the battery tray and cannot be replaced independently
- Charging system voltage tends to be higher during colder temperatures and lower as the battery temperature rises
- Typically, a 5-volt reference signal is sent to the battery temperature sensor from the PCM
- This signal voltage is grounded through the sensor return circuit
- As the battery temperature increases, sensor resistance decreases and the PCM receives a higher voltage signal
- When the battery temperature decreases, the voltage signal drops
The PCM also uses battery temperature as a basis for activating heated oxygen sensor operation and evaporative emissions component activation.
Several tools will be instrumental in successfully diagnosing this code
- A suitable OBD-II scanner (or code reader) and a digital volt/ohmmeter will be most helpful in performing a successful diagnosis
Begin with a visual inspection of all wiring and connectors
- Repair or replace damaged, disconnected, shorted, or corroded wiring, connectors, and components as necessary
- Always retest the system after repairs are completed to ensure success.
If all system wiring, connectors, and components (Including fuses) appear to be in normal working order, connect the scanner (or code reader) to the diagnostic connector and record all stored codes and freeze frame data
- This information can be extremely helpful in diagnosing intermittent conditions that may have contributed to this code being stored
- Continue by clearing the code and operating the vehicle to see if it returns
- This will help to determine whether or not the malfunction is intermittent
After the codes are cleared, test drive the vehicle to see if the code returns
- If the code fails to immediately return, you may have an intermittent condition
- Intermittent conditions can prove to be quite a challenge to diagnose and in extreme cases may have to be allowed to worsen before a correct diagnosis can be made
Repair or replace electrical circuitry and/or components as required, then reset the codes and retest the system
- If all electrical circuitry appears to be in good working order, test for a system voltage signal and a ground signal at the battery temperature sensor
- If your findings coincide with manufacturer’s specifications, test the resistance of the battery temperature sensor and compare your findings with manufacturer’s specifications
- If the actual data does not line up with the manufacturer’s specified reference voltage, replace the battery temperature sensor
- If you still have not located the problem, disconnect the PCM connector and perform a continuity test on all related circuits
- Compare your findings to manufacturer’s specifications and repair open or shorted circuits as necessary
- If no problems are detected in any of the previous tests, suspect PCM failure
- PCM failure is very rare