P0880

ALLISON AUTOMATIC TRANSMISSION

DTC P0880
Circuit Description for Allison Automatic Transmission
DTC P0880 will set if an abnormal power-down sequence has occurred. This condition means the transmission control module (TCM) has lost battery positive voltage circuit, supply voltage, before it has finished saving information from that drive cycle. This process is usually completed in less than 10 seconds.

DTC P0880 is a type C DTC.

DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0880 TCM Power Input Signal

Conditions for Running the DTC
^ The components are powered and ignition voltage is greater than 9.0 volts and less than 18 volts.
^ Loss of TCM supply voltage before drive cycle data is saved.

Conditions for Setting the DTC
DTC P0880 sets during the next ignition cycle if the TCM loses TCM supply voltage less than 10 seconds after the ignition voltage has been turned off.

Action Taken When the DTC Sets
^ The TCM does not illuminate the malfunction indicator lamp (MIL).
^ DTC P0880 will be stored in TCM history.
^ Loss of adaptive information for drive cycle. Revert to previous adaptive settings.
^ 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.

Test Description








The numbers below refer to the step numbers on the diagnostic table.
2. This step tests the system voltage.
4. This step tests the vehicle charging system.
5. This step tests the wiring harness for opens or shorts.