For 1990-2009 cars

### Circuit Description

The engine control module (ECM), transaxle control module (TCM), and the body control module (BCM) communicate with each other over the controller area network (CAN) bus circuits 2500 and 2501. The CAN BUS is a communications protocol that is used by the TCM to communicate vital engine control inputs from a stand-alone engine controller. The diagnostic checks the information received in CAN to determine whether a pass or fail code. Before checking the information, the TCM makes sure the CAN messages are being received by checking the BUS failure timer.

### Conditions for Setting the DTC

DTC P0727 will set if:

• | CAN bus signal for the engine speed circuit is not responding for 2 seconds

• | System voltage is between 8 and 18 volts

• | Engine speed is greater than 500 rpm for 5 seconds and not at fuel cutoff

### Diagnostic Aids

• | This code does not indicate a problem with the TCM. It does indicate the ECM is not sending engine speed to the TCM.

• | Determine the problem or look for trouble code(s) in the ECM.