P0725-Engine Speed Sensor Circuit: Notes

For a complete wiring diagram , refer to appropriate SYSTEM WIRING DIAGRAMS article.

Theory of Operation

The Transmission Control System calculates the engine RPM by directly reading the engine crank position sensor. It compares the calculated value to the engine speed sensor signal transmitted from the Engine Control System over the controllers internal BUS. The calculated engine RPM is also compared to a minimum and a maximum value.

NOTE: Due to the integration of the Powertrain Control Module (PCM) and Transmission Control Module (TCM), BUS communication between the modules is internal and unserviceable.

When Monitored:
Continuously every 7 msec with the ignition on and engine running.
Set Condition:
This DTC will set when the calculated engine speed is less than 390 RPM with the engine running, or greater than 8000 RPM, for the period of 2.0 seconds. The PCM will place the Transmission in Limp-in when this DTC is set. Note: This is not a Transmission Input Speed Sensor DTC.

Possible Causes
RELATED ENGINE DTC'S PRESENT
CRANK POSITION SENSOR OR WIRING
POWERTRAIN CONTROL MODULE

Always perform the 45RFE/545RFE PRE-DIAGNOSTIC TROUBLESHOOTING PROCEDURE before proceeding.