Per the Allison 3000/4000 WTEC-II series troubleshooting manual:
WTEC II ELECTRONIC CONTROLS TROUBLESHOOTING MANUAL
NOTE: If a DO NOT SHIFT condition is present at this time, the shift lever should remain in the same position where it was when the DO NOT SHIFT was detected. If the lever is moved, a continuous tone will be heard until the lever is returned to the correct position.
NOTE:If an oil level sensor is present, then fluid level will be displayed first.
Diagnostic code display is achieved by depressing the ⇑ (Up) and ⇓ (Down) arrow buttons or the DISPLAY MODE button a second time.The code list position is the first item displayed, followed by the main code and the Subcode. Each item is displayed for two seconds. The two second item display cycles continuously until the next code list position is accessed. The following list represents the display cycle using Code 25 11 as an example:1. Code list position — d12. Main code — 253. Subcode —114. Cycle repeats — d1
To view the second, third, fourth, and fifth positions (d2, d3, d4, and d5), momentarily press the MODE button as explained above.Momentarily press the MODE button after the fifth position is displayed to restart the sequence of code list positions.An active code is indicated by the MODE ON indicator (active indicator) illuminating when a code position is displayed. In the normal operating mode, the MODE ON display indicates secondary mode operation.Any code position which does not have a diagnostic code logged will display “– –” for both the main and Subcodes. No diagnostic codes are logged after an empty code position.
B.Clearing Active Indicators. A diagnostic code’s active indicator can be cleared, which allows the code to be removed from the code list.The active indicator clearing methods are:
1. Power down — All active indicators, except Code 69 34 (refer to the code chart), are cleared at ECU power down.
2. Self-clearing — Some codes will clear their active indicator when the condition causing the code is no longer detected by the ECU.
3. Manual — Some active indicators can be cleared manually, while in the diagnostic display mode, after the condition causing the code is corrected.
C.Manually Clearing Codes and Active Indicators from the Code List. To clear active indicators or all codes:
1. Enter the Diagnostic Display Mode.
2. Press and hold the MODE button, approximately three seconds, until a tone sounds once. All active indicators are cleared. To remove all codes, press and hold the MODE button for ten seconds until the shift selector tone sounds twice.All codes will be cleared at ECU power down.
CAUTION:If an active indicator is cleared while the transmission is locked in a forward range or reverse (fail-to-range), the transmission will remain in the forward range or reverse afterthe clearing procedure is completed. Neutral must be manually selected.
D.Exiting the Diagnostic Display Mode. Exit the diagnostic display mode using one of the following procedures:
1. On a pushbutton shift selector, press the ⇑ (Up) and ⇓ (Down) arrow buttons at the same time or press any range button, D, N, or R. The shift (D, N, or R) is commanded if not inhibited by an active code.
2. On a lever shift selector, momentarily press the DISPLAYMODE button or move the shift lever to any shift position other than the one it was in when the diagnostic display mode was activated. If the shift is inhibited, the ECU will continue to command the current range and sound the tone continuously until the lever is returned to its original position.
3. Wait until timeout (approximately 10 minutes) and the system will automatically return to the normal operating mode.
4. Turn off power to the ECU (turn off the vehicle engine at the ignition switch)
The manual can be found here:
http://ww2.justanswer.com/uploads/H...ison_transmission_md3060_trouble-shooting.pdf
The above info was copied from Section 6.
I got to know this manual inside and out when my 1994 RV gave me problems. I wound up replacing part of the transmission wiring harness, the harness was getting spurious signals in the sensor wiring.