P0701

ALLISON AUTOMATIC TRANSMISSION

DTC P0701





Circuit Description for Allison Automatic Transmission
The Transmission Control Module (TCM) monitors the status of the pressure switches at start-up to detect the presence of hydraulic pressure.

Conditions for Running the DTC
The components are powered and ignition voltage is greater than 9 V and less than 18 V. Engine speed is greater than 200 RPM and less than 7500 RPM for 5 seconds.

Conditions for Setting the DTC
DTC P0701 sets when the TCM detects the following conditions:
^ Transmission fluid temperature is above -25°C (-13°F).
^ All pressure switches do not indicate pressure (at start-up).
^ Engine speed is above 500 RPM for 6 seconds or 400 RPM for 15 seconds.
^ Forward or reverse range is selected.

Action Taken When the DTC Sets
^ DTC P0701 will be stored in TCM history.
^ TCM inhibits TCC engagement.

Conditions for Clearing the MIL/DTC
A Scan Tool can clear the code from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without failure.

Diagnostic Aids
DTC P0701 may be logged if a forward or reverse range is selected immediately after the engine is started and before the TCM detects pressure at the switches (2 to 6 seconds after engine start).
A plugged control main filter may cause this code to set.
^ Inspect the wiring for poor electrical connections at the TCM. Look for the following conditions:
- A bent terminal
- A backed-out terminal
- A damaged terminal
- Poor terminal tension
- A chafed wire
- A broken wire inside the insulation.
^ When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.
^ You may have to drive the vehicle inn order to experience a fault.

Test Description
The number(s) below refers to the step number(s) on the diagnostic table.
5. This step tests for line pressure.