Code
P1492
PLYMOUTH
P — Powertrain
Battery Temperature Sensor Voltage Too High
Views:
UK: 23
EN: 65
RU: 31
AI status
Completed
Completed
100%
Causes
- Open or intermittent wiring between battery temperature sensor and PCM (open circuit can pull voltage high)
- Short to battery voltage (12V) on the sensor signal
- Corroded, loose, or damaged sensor connector
- Failed battery temperature sensor or sensor module
- Poor grounding of sensor or related circuits
- PCM input fault (rare) or internal module failure
Symptoms
- Malfunction indicator lamp (MIL) or check engine light illuminated
- Incorrect or missing battery temperature reading in scan tool
- Reduced or incorrect charging/charging system behavior (charger/regulator may alter strategy based on temp)
- Possible no-start or charging system limp behavior on some vehicles
- DTC stored and possibly freeze-frame data recorded
What to check
- Retrieve freeze frame and live data with a scan tool — verify battery temperature value and monitor signal while key on/engine off and during cranking
- Visual inspection of battery temperature sensor, connector, and wiring harness for damage, corrosion, or pin push-out
- Back-probe sensor signal and reference/ground with a voltmeter; compare to expected ranges
- Check circuit continuity and resistance between sensor and PCM connector
- Wiggle-test wiring while monitoring signal to look for intermittent faults
- Inspect battery and charging system for unrelated voltage issues that could affect sensor circuit
Signal parameters
- Typical sensor signal is a low-voltage analog to PCM (0–5 V).
- High-voltage fault threshold: sensor circuit > ~4.5 V (varies by manufacturer).
- Open-circuit often reads near battery/ignition voltage on the PCM input or a maximum sensor voltage.
- At normal ambient temp the sensor voltage generally sits in the mid-range (varies by sensor type and vehicle).
Diagnostic algorithm
- Connect a scan tool, record freeze-frame and PID data for battery temperature and related signals. Note any other stored codes.
- Visually inspect the battery temperature sensor and wiring harness for damage, corrosion, or loose connectors. Repair if obvious damage found.
- With ignition ON (engine OFF), back-probe the sensor signal wire and measure voltage to ground. Compare to expected range (0–5 V). A voltage above ~4.5 V indicates a high-voltage condition.
- Disconnect the sensor connector and observe change in signal at the PCM (if safe per service manual). An open should typically drive the PCM input to a defined state — consult vehicle data. If signal behavior doesn’t change, suspect PCM or wiring short to battery voltage.
- Check continuity and resistance from sensor connector to PCM pin(s). Look for open, high resistance, or short to battery positive. Repair any harness faults.
- Test or measure sensor resistance if service data available (warm/cold resistance vs. temp). Replace sensor if out of specification.
- Inspect and verify grounds for the sensor circuit and related modules. Repair as needed.
- If wiring and sensor check good, consider PCM input fault — verify with wiring harness checks and consult technical service information before replacing PCM.
- After repairs, clear codes, perform functional test/road test, and re-scan to confirm the fault does not return.
Likely causes
- Broken/open wire or connector to battery temperature sensor
- Sensor harness shorted to vehicle battery positive or ignition feed
- Contaminated or corroded connector at sensor
- Failed temperature sensor or battery sensor module
- Faulty PCM input (least likely)
Fault status
Status
P1492 — Battery Temperature Sensor Voltage Too High. PCM sees battery temperature sensor voltage above expected range. Possible open circuit, short to 12V, sensor failure, or wiring/connector fault. MIL illuminated.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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