P0876

ALLISON AUTOMATIC TRANSMISSION

DTC P0876

DTC P0876 Step 1 - 9:

DTC P0876 Step 10 - 13:

Circuit Description for Allison Automatic Transmission

Important: DTC P0876 was previously P1714.

The Pressure Switch Manifold (PSM) is a multiple switch assembly made up of three N/O pressure switches and one N/C pressure switch for reverse pressure. Fluid pressure is supplied to the reverse pressure switch when the manual selector valve is in any position except Reverse. When the manual selector valve is moved to Reverse, pressure to the reverse pressure switch is cut off causing the switch to close.

DTC P0876 is a type B DTC.

Conditions for Running the DTC
^ The components are powered and ignition voltage, is greater than 9V and less than 18 V.
^ Engine speed is greater than 200 RPM and less than 7,500 RPM for 5 seconds.
^ The Park/Neutral Position switch is enabled and functional.
^ TFT is greater than 0°C (32°F).
^ DTCs P0706, P0708, P1713, P1715 are not active.

Conditions for Setting the DTC
DTC P0876 sets when a forward range has been selected and the reverse pressure switch remains in the mechanically open/electrically off position.

Action Taken When the DTC Sets
^ The TCM illuminates the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the Conditions for Setting the DTC are met.
^ The transmission will lock in neutral.
^ DTC P0876 will be stored in the TCM history.
^ The TCM freezes shift adapts (DNA).
^ Locked in neutral.
^ 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
^ 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 in order to experience a fault.
^ This DTC could indicate a hydraulic leak path exhausting pressure from the reverse pressure switch.

Test Description
The numbers refer to the step numbers on the diagnostic table.
5. This step tests the TCM response function
6. This step tests the transmission wiring harness integrity.
7. This step tests and evaluates the internal wiring harness.
8. This step tests the Pressure Switch Manifold (PSM) for a failed condition.