Fault in the transmission output speed sensor circuit.
SYMPTOMS
- Check-engine light
- Possible rough running
- Reduced performance
- Worse fuel economy
LIKELY CAUSES
- Faulty output speed sensor
- Open, shorted, or corroded wiring/connector
- Loss of reference voltage or ground
- ECM/PCM fault (rare)
DIAGNOSIS STEPS
- Inspect the output speed sensor connector and wiring for damage or corrosion
- Measure sensor resistance/voltage against specification
- Check reference voltage and ground at the connector
- Compare live data to a known-good value
- Replace the sensor if out of spec
RELATED PARTS
- Output speed sensor