Diagnostic Trouble Code Response - PREVOST X3-45 COACH 2018 Operator's Manual

Table of Contents

Appendix C – Allison Diagnostic Troubleshooting Codes

To begin the diagnostic process:

1. Bring the vehicle to a stop at a safe location.

2. Apply the parking brake.

To display stored codes:

1. Simultaneously press the

enabled) to access the Diagnostic Display Mode. With Prognostics disabled, press the

and

(Downshift) arrow buttons twice.

2. Press the MODE button to read the next code in the queue, if any.

To clear all active stored codes:

While in Diagnostic Mode, clear all active codes by pressing and holding the MODE button for

approximately three seconds until the MODE message flashes. Release the MODE button. The MODE

message should not remain illuminated if the active DTC shown in the display has cleared.

While in Diagnostic Mode, press and hold the MODE button for 10 seconds to clear both active codes

and inactive codes. The MODE message flashes a second time indicating all codes are cleared from the

queue.

Exiting Diagnostic Mode

Exit the diagnostic mode by one of the following methods:

1. Press simultaneously the

pushbutton shift selector.

2. Press any range button «D», «N» or «R» on the pushbutton shift selector.

3. After approximately 10 minutes of inactivity at the pushbutton shift selector, the diagnostic mode

automatically exits and returns to normal operating mode.

4. Turn off power to the TCM (shut off the engine using the ignition key).

NOTE

Be sure to record all codes displayed before they are cleared. This is essential for troubleshooting.

NOTE

If clearing a code while locked in a «D» (Drive) or «R» (Reverse) position (fail-to-range), the

transmission will still be in «D» (Drive) or «R» (Reverse) when the clearing procedure is completed.

«N» (Neutral) must be manually selected.