P0725 (18) - Engine Speed Sensor Circuit

Name of Code:
P0725 (18) - Engine Speed Sensor Circuit

When Monitored:
Continuously with engine running.

Set Condition:
This code is set when the engine speed sensed by the Transmission Control Module (TCM) is less than 390 RPM or greater than 8000 RPM for more that 2.0 seconds.

Theory of Operation:
The TCM uses the crank sensor signal to calculate engine RPM. The TCM uses the RPM data broadcast over the communication bus to determine if the engine is running. The TCM continuously verifies that it's calculated engine speed is within range while the engine is running.

Transmission Effects:
The MIL will illuminate and the transmission system will default to the Logical Shutdown routine.

Possible Causes:
- Open or short in engine speed sensor circuit. (Crank sensor signal)
- TCM connector problems (Crank sensor signal or sensor ground terminals)
- Open or short in sensor ground circuit
- TCM
- PCM.