P0836

ALLISON AUTOMATIC TRANSMISSION

DTC P0836

DTC P0836 Step 1 - 4:

DTC P0836 Step 5 - 16:

Circuit Description for Allison Automatic Transmission
Detect abnormal conditions for the four wheel drive indication switch input. Detect four wheel drive status using speed and gear ratios. DTC P0836 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.
^ DTCs P0721 and P0722 output speed sensor circuits are not active.
^ Output speed is above 60 RPM.
^ Transmission fluid temperature is between 20°C (68°F) and 130°C (266°F).
^ Shift is complete and neutral range is not selected.

Conditions for Setting the DTC
DTC P0836 sets when one of the following conditions occur:
^ The transfer case switch indicates high range, and the calculated range is low range for 5 seconds or more.
^ The transfer case switch indicates low range, and the calculated range is high range for 5 seconds or more.

Action Taken When the DTC Sets
^ DTC P0836 will be stored in the TCM history.
^ Illuminates the MIL on the second occurrence.
^ 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.
^ Inspect for any transmission DTCs that may have reset.

Test Description
The numbers refer to the step numbers on the diagnostic table.
2. This step tests the status of the 4WD Low switch.
3. This step tests for a 4WD switch failure to ground.
4. This step tests for a short in the wiring harness.
9. This step tests for a 4WD switch failure to an open state.
10. This step tests for an open in the wiring harness.