Code
P1492
JEEP
P — Powertrain
Battery Temperature Sensor Voltage Too High
Views:
UK: 23
EN: 62
RU: 36
AI status
Completed
Completed
100%
Causes
- Open or shorted battery temperature sensor wiring (short to battery/ignition voltage)
- Corroded or disconnected sensor connector or terminals
- Failed battery temperature sensor (thermistor open or internally shorted)
- Poor ground or reference supply to sensor circuit
- PCM/ECM input circuit fault or software anomaly
Symptoms
- DTC P1492 stored and Malfunction Indicator Lamp (MIL) may or may not be illuminated
- Possible incorrect battery temperature reading on scan tool (very high or pegged)
- Reduced charging or charging system adaptations (depending on vehicle logic)
- Intermittent faults if wiring is broken or intermittent
What to check
- Use a scan tool to read PIDs: battery temperature, battery voltage, and stored freeze frame data
- Visually inspect sensor, connector, and wiring for damage, corrosion, or water entry
- Backprobe the sensor connector with ignition on and engine off to measure signal voltage
- Measure resistance of the sensor (with sensor removed) and compare to manufacturer specification
- Perform continuity and short-to-voltage/short-to-ground checks between sensor and PCM connector
- Wiggle test wiring while watching live data for intermittent changes
Signal parameters
- Sensor signal voltage should vary with temperature; typical operating range is roughly 0.1–4.5 V (check OEM spec)
- A voltage near battery/ignition voltage (for example >4.5 V) is considered a high input condition
- Battery temperature sensor is usually a thermistor—resistance changes with temperature (consult service manual for exact ohms @ specific temps)
- PCM provides reference voltage and measures the sensor return; check both reference and ground continuity
Diagnostic algorithm
- Retrieve DTC and freeze frame with a scan tool. Record live battery temperature PID and battery voltage.
- Visually inspect sensor, harness, and connector for corrosion, damage, or signs of water intrusion. Repair as needed.
- Backprobe sensor connector. With ignition ON (engine OFF), measure sensor signal voltage at the PCM pin and at the sensor. If voltage is high (~battery voltage), suspect short to power or open/failed sensor.
- Disconnect sensor and measure resistance across sensor terminals. Compare to OEM resistance vs temperature chart. If open or out of range, replace sensor.
- Check for short to voltage: with harness disconnected, measure resistance between the signal circuit and battery positive. Low resistance indicates short to power; trace and repair wiring.
- Check continuity from sensor connector to PCM connector and verify PCM reference and ground circuits are within spec.
- If wiring and sensor test good, consider PCM input fault. Confirm with manufacturer diagnostics before replacing PCM.
- After repairs, clear codes and perform functional test/drive cycle while monitoring live data to confirm the fault does not return.
Likely causes
- Wiring short to battery voltage at or near the sensor
- Corrosion or water intrusion in sensor connector
- Failed battery temperature sensor (out of spec resistance/voltage)
- Loose or damaged connector at the PCM
Fault status
Status
Battery Temperature Sensor Circuit — Voltage Too High (P1492). High sensor signal voltage detected; inspect sensor, wiring, connector, and PCM inputs.
Repair difficulty: Medium
Diagnostic time: 0.5-1.5 hours
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