Allison - Automatic Transmission

DTC P0700

Circuit Description

This diagnostic trouble code (DTC) indicates that a related transmission DTC set in the transmission control module (TCM). The engine control module (ECM) receives the TCM DTC information over the serial data circuit. The ECM turns ON the malfunction indicator lamp (MIL) when the TCM sends a message over the serial data circuit requesting MIL illumination.


DTC P0700 is a type A DTC.


DTC Descriptor

This diagnostic procedure supports the following DTC:


DTC P0700 Transmission Control Module (TCM) Requested MIL Illumination


Conditions for Running the DTC

The engine is running.


Conditions for Setting the DTC

The ECM receives a serial data message from the TCM in order to illuminate the MIL.


Action Taken When the DTC Sets

* The ECM illuminates the MIL when the diagnostic runs and fails.
* The ECM records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.



Conditions for Clearing the DTC

* The ECM turns OFF the MIL after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
* A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
* A scan tool can clear the code from TCM history. The TCM automatically clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without failure.