Ram B1500, B2500, B3500, 1999-2003

Battery Temperature Sensor

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This sensor is located beneath the battery attached to a mounting hole on the battery tray. Models that have dual batteries have one sensor, on the driver's side battery.

Input from this sensor to the PCM is used to determine the charging rate.

Description & Operation



The Battery Temperature Sensor (BTS) is attached to the battery tray located under the battery.

The BTS is used to determine the battery temperature and control battery charging rate. This temperature data, along with data from monitored line voltage, is used by the PCM (ECM Diesel) to vary the battery charging rate. System voltage will be higher at colder temperatures and is gradually reduced at warmer temperatures.

The PCM sends 5 volts to the sensor and is grounded through the sensor return line. As temperature increases, resistance in the sensor decreases and the detection voltage at the PCM increases.

The BTS is also used for OBD II diagnostics. Certain faults and OBD II monitors are either enabled or disabled, depending upon BTS input (for example, disable purge and enable Leak Detection Pump (LDP) and O2 sensor heater tests). Most OBD II monitors are disabled below 20F.

The Battery Temperature Sensor (BTS) is attached to the battery tray located under the battery.

The BTS is used to determine the battery temperature and control battery charging rate. This temperature data, along with data from monitored line voltage, is used by the PCM (ECM Diesel) to vary the battery charging rate. System voltage will be higher at colder temperatures and is gradually reduced at warmer temperatures.

The PCM sends 5 volts to the sensor and is grounded through the sensor return line. As temperature increases, resistance in the sensor decreases and the detection voltage at the PCM increases.

The BTS is also used for OBD II diagnostics. Certain faults and OBD II monitors are either enabled or disabled, depending upon BTS input (for example, disable purge and enable Leak Detection Pump (LDP) and O2 sensor heater tests). Most OBD II monitors are disabled below 20F.

Removal & Installation



  1. Remove battery.
  2.  
  3. Pry sensor straight up from battery tray mounting hole to gain access to electrical connector.
  4.  
  5. Disconnect sensor from engine wire harness electrical connector.
  6.  

To Install:

  1. Pull electrical connector up through mounting hole in top of battery tray.
  2.  
  3. Connect sensor.
  4.  
  5. Snap sensor into battery tray.
  6.  
  7. Install battery.
  8.  

  1. Remove battery.
  2.  
  3. Pry sensor straight up from battery tray mounting hole to gain access to electrical connector.
  4.  
  5. Disconnect sensor from engine wire harness electrical connector.
  6.  

To Install:

  1. Pull electrical connector up through mounting hole in top of battery tray.
  2.  
  3. Connect sensor.
  4.  
  5. Snap sensor into battery tray.
  6.  
  7. Install battery.
  8.  

  1. Remove the battery.
  2.  
  3. Disconnect the sensor pigtail harness from the engine wiring harness.
  4.  
  5. Pry the sensor straight up from the battery tray mounting hole.
  6.  
  7. To install, feed the harness through the mounting hole and snap in the sensor.
  8.  



Click image to see an enlarged view

Fig. Battery temperature sensor location

 
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