The P1493 code on your 2020 Ram 2500 indicates that the battery temperature sensor is sending a lower than expected voltage signal to the PCM. This Stellantis-specific code affects your Ram's 6.4L HEMI V8 or 6.7L Cummins diesel engine's charging system, indicating the PCM is receiving a signal suggesting abnormally high battery temperature.
Understanding P1493 on Ram 2500
The battery temperature sensor uses a thermistor that changes resistance with temperature - higher temperature means lower resistance and lower voltage signal. Code P1493 sets when sensor voltage is too low, indicating either an actual high temperature condition or more likely a sensor/circuit fault causing incorrect low readings.
Common Symptoms
- Check engine light illuminated
- Battery undercharging
- Slow cranking, especially in cold weather
- Dead battery symptoms despite good battery
- Charging system warning light
- Dim lights during extended idle
Primary Causes
- Shorted battery temperature sensor
- Short to ground in sensor wiring
- Water intrusion in sensor connector
- Damaged wiring harness
- Sensor positioned near heat source
- Failed sensor (low resistance)
- PCM input protection circuit issue
Diagnostic Procedure for 2020 Ram 2500
Locate the battery temperature sensor attached to or near the battery. Disconnect the sensor and measure its resistance - compare to the temperature vs. resistance specification chart. If resistance is abnormally low or the sensor shows a short, replacement is needed. Check wiring for shorts to ground by measuring resistance between signal wire and chassis. Inspect for water intrusion in the connector.
Repair Solutions
Replace shorted or out-of-specification battery temperature sensor. Repair wiring shorts to ground by replacing damaged wire sections. Dry and clean connectors with water intrusion, applying dielectric grease to prevent recurrence. Verify sensor is not mounted near heat sources like exhaust or turbo components. Clear codes and verify proper sensor operation across temperature ranges.