Ignition/Distributor Engine Speed Input Circuit Malfunction
The engine speed input circuit (crankshaft position sensor signal) is not being received by the PCM. This prevents the engine from determining crankshaft position and timing, which is critical for starting and running the engine.
What You Might Notice
- Engine cranks but will not start
- Malfunction Indicator Light illuminated
- Misfire, hesitation, or stumble during acceleration
- Lack of engine power or performance
- Stalling during operation
Most Common Causes
- 1
Faulty crankshaft position sensor
The CKP sensor has failed or is producing an erratic signal. This is the most common cause of P0320 codes.
- 2
Open circuit in wiring harness
A break or loose connection in the control or ground circuit between the sensor and PCM prevents signal transmission to the engine computer.
- 3
Short to ground in power supply
The power supply circuit to the sensor is shorted to ground, cutting off voltage to the sensor and preventing operation.
- 4
PCM failure
The engine control module has failed or is unable to process the crankshaft position signal, though this is less common than sensor failure.
How to Diagnose It
- 1
Check Faulty crankshaft position sensor — The CKP sensor has failed or is producing an erratic signal. This is the most common cause of P0320 codes.
- 2
Check Open circuit in wiring harness — A break or loose connection in the control or ground circuit between the sensor and PCM prevents signal transmission to the engine computer.
- 3
Check Short to ground in power supply — The power supply circuit to the sensor is shorted to ground, cutting off voltage to the sensor and preventing operation.
- 4
Check PCM failure — The engine control module has failed or is unable to process the crankshaft position signal, though this is less common than sensor failure.
How to Fix It
- 1
Replace crankshaft position sensor
Remove the faulty CKP sensor and install a new one. Test the new sensor output with a scope or multimeter to confirm proper operation before starting the engine.
- 2
Inspect and repair wiring harness
Check the entire signal harness from the crankshaft sensor to the PCM for breaks, corrosion, or loose connectors. Repair or replace damaged wiring and ensure all connections are secure.
- 3
Check sensor power and ground
Use a multimeter to verify proper voltage and ground at the sensor connector. Compare readings to manufacturer specifications and trace the circuit if voltage is missing.
- 4
Replace or reprogram PCM
If all wiring and sensors test good, the PCM may require reprogramming or replacement. Consult manufacturer specifications and consider professional diagnostics before replacing the control module.
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