P0701

LCT 1000 Allison Transmission

DTC P0701

Circuit Description
The transmission control module (TCM) monitors the status of the pressure switches at start-up, in order to detect the presence of hydraulic pressure.

DTC P0701 is a type C DTC.

DTC Descriptor
This diagnostic procedure supports the following DTC:

DTC P0701 Transmission Control System Performance

Conditions for Running the DTC
^ The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts.
^ Engine speed is greater than 200 RPM and less than 7,500 RPM for 5 seconds.

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

Action Taken When the DTC Sets
^ The TCM does not illuminate the malfunction indicator lamp (MIL).
^ DTC P0701 is stored in TCM history.
^ The TCM inhibits torque converter clutch (TCC) engagement.

Conditions for Clearing the DTC
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.

Diagnostic Aids
^ Inspect the wiring for poor electrical connections at the TCM. Inspect 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 in order to experience a condition.
^ 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, 2-6 seconds after the engine starts.
^ A plugged control main filter may cause DTC P0701 to set.

Test Description

Step 1 - Step 8:

The number below refers to the step number on the diagnostic table.
5. This step tests for line pressure.