DTC Descriptions: Schematic

Theory of operation:  The TCM uses either a EATX RPM signal (simulated Crank Sensor signal) or the TCM uses the Crank Position Sensor signal to calculate engine RPM depending on the engine application. The signal supplied by the PCM and uses a dedicated circuit is called the EATX RPM Signal circuit. The Crank Position Sensor signal is a spliced circuit from the engine Crank Position Sensor. Check the wiring schematics to determine which (engine speed sensor circuit) is used in the vehicle. If the TCM interprets this signal to be out of range when the engine is running (as reported by the PCM over the bus) the code is set.

Transmission Effects:  The MIL illuminates and the transmission system defaults to Limp-in mode.

Possible causes: 

1. Open or short in EATX RPM Signal circuit.
2. Open or short in Crank Position Sensor Signal circuit.
3. Open or short in Crank Position Sensor ground circuit.
4. TCM and/or PCM connector problems
5. TCM
6. PCM

Name of code: P1694(19) - Bus Communication with Engine Module