Copyright 2019 Discovery Owner's Association, Inc.

Allison Transmission Info

This procedure will allow you to check your transmission fluid level from inside the vehicle, and it is also more accurate than checking via the dipstick.

To enter the transmission oil level display mode, press the UP and DOWN arrow buttons simultaneously on the mode selector. A two-minute countdown begins when the following conditions are met: Engine is at idle Transmission sump oil is at operating temperature Transmission output shaft has stopped Transmission is in neutral Oil level sensor is functioning properly The display should show *8 and then count down to 0. Note that it will take two minutes to complete this countdown. During the countdown, the display flashes and a count (8,7,6,5,4,3,2,1) occurs reducing by one digit every 15 seconds.

NOTE: Failure to meet any of the above conditions will stop the two minute countdown. The shift selector will then display one of the following Oil Level Codes to show the reason for the countdown interruption. The countdown will resume where it stopped once all conditions have been met. Shift selectors with single digit display will display the codes one digit at a time. Shift selectors with two digit displays will display the codes two digits at a time.

oL 0X Setting time too short
oL 50 Engine RPM too low
oL 59 Engine RPM too high
oL 65 Neutral not selected
oL 70 Sump fluid temperature too low
oL 79 Sump fluid temperature too high
oL 89 Output shaft rotation detected
oL 95 Oil level sensor failed

After the two minute countdown, the shift selector displays the oil level data as in the following examples:

o, L, o, K Fluid level is correct
o, L, L, o, 1 or OL, LO, 01 Fluid level is 1 quart low
o, L, H, 1 or OL, HI, 01 Fluid level is 1 quart high

To exit the oil level display mode, press the NEUTRAL button or simultaneously press the UP and DOWN arrows twice.

1. To enter the diagnostic mode, simultaneously press the UP and DOWN arrows once if the transmission does not have an oil level sensor and twice if the transmission is equipped with an oil level sensor.

2.If no codes are present, the display will show a dash (-) on a single digit display shift selector or a double dash (--) on a two digit display shift selector. If codes are present, the code registered in the first of five code positions will display on the shift selector. The code list position is the first item displayed, followed by the two digit main code and then the two digit sub code. Each item is displayed for about one second. The display cycles continuously until the next code list position is selected by pressing the MODE button. The following list represents a code display using code 25 11 as an example:

  • Code list position - d 1 (will be displayed one digit at a time on a shift selector with a single digit display)
  • Main code - 2 5 (will be displayed one digit at a time on a shift selector with a single digit display)
  • Sub code - 1 1 (will be displayed one digit at a time on a shift selector with a single digit display)
  • Cycle will continue to repeat itself

3. To view the codes in the second, third, fourth and fifth positions (d 2, d 3, d 4, d 5), momentarily press the MODE button as explained above in step 2. Momentarily pressing the MODE button when the fifth position is displayed, will restart the sequence by displaying code position one (d 1).

4. If a listed code is active, the LED indicator next to the MODE button will be illuminated on shift selectors with a single digit display. On shift selectors with a two digit display, the MODE ON light will appear on the display.

1. While in the diagnostic mode. push and hold the MODE button for approximately ten seconds to clear all of the codes. Shift selectors with two digit displays will sound a tone at about eight seconds and a second tone at about ten seconds indicating that all of the codes are cleared. Shift selectors with a single digit display will flash the LED indicator at about three seconds and again at about then seconds indicating that all of the codes are cleared.

2. Drive the vehicle and check for code reoccurence. If codes continue to reoccur, bring the vehicle to an authorized Allison Transmission repairing outlet to determine and repair problem causing the codes.

Press the NEUTRAL button or simutaneously press the UP and DOWN buttons.

Fault Codes
-Submitted by Bob Cook

If you can change oil on a car you can change the transmission filters on the D. The kit consists of two filters, two sets of gaskets and three sets of rings. There are two pair of round (looking of a cross section of the O ring) O-rings and some square ones which are called square cuts. Part number is Allison - Kit, Filter 29526899. We have the short 2" pan.

Most of the oil does drain from the plug and you don't remove the pan (control module), instead, each filter has it's own cover which will leak some fluid when removed.

The filter kit comes with a diagram for changing the filters, albeit a small one. Our transmission is an MD 3060.

Here are the step-by-step instructions:
1. If you are only changing the filters, don't drain the fluid. If you are draining the fluid make sure it is at operating temperature, between 160 to 200 degrees, it's recommended and it will drain quicker, it's also hot on the skin! So Be Careful!f
2. Get a big drain pan which holds at least three gallons, put it under the drain plug and filter covers.
3. Remove the drain plug from the control module. As I mentioned above, the control module is what we would call the "pan" on a car transmission. Let it drain into the drain pan. There is a 3/8" square hole in the drain plug, just use a 3/8 drive and the male end of a 3/8" extension.
4. Remove the 12 bolts, six on each cover.
5. Remove the two filter covers from the bottom of the control module, they will come straight down and may require "coaxing". Don't use anything that will cut or dent the covers!
6. Remove the filter from one cover only.
7. Remove all the O-rings from that one cover. Use the other one as a guide 'til all the new rings are in place.
8. Lubricate and install the O-rings on that cover. Use whatever new O-rings match the old O-rings, there may be extra new parts.
9. Reinstall the new filter on that cover.
10. Repeat steps 5 - 8 on the other cover.
11. On my transmission it had gaskets on each cover, instead of the square cut seals. Depending on the model of your transmission and when it was made, this can vary, that's why I say put on whatever you took off.
12. Reinstall the covers into the control module, press them up into place until they are seated. Don't use the bolts to draw them into place as this can damage the covers or strip the threading in the bolt holes.
13. Reinstall the 12 bolts and torque them to 38 - 45 lbs./ft. If you don't have a torque wrench, just tighten it "very" hand tight with the appropriate box wrench. If you were to use a socket with a long handle you can easily over-torque and therefore strip bolt holes. (I like to use the criss-cross method of torquing bolts to avoid warping the cover. I tighten 1 bolt to half specs, then do the oposite one, then back to the one next to the first one, then accross, etc. Once all around I repeat to full torque. Like you would do on a wheel or head bolts, probably overkill as the covers are so small, but I like to stay in the habit).
14. If you removed the drain plug, and on the first time you will, make sure the drain plug and it's O-ring is OK and replace it. Tighten this to 18 24 lbs./ft.
15. Refill the fluid. On our units it should take 14 quarts. I would add three gallons, start the engine and check the fluid from the transmission console. Then add any more fluid if needed. Rely on the electronic console and not on the dip stick.
16. Clean up and have a beer or the beverage of your choice.
-Submitted by Herb Petersen

On some D's, the buttons on the transmission shift light console are not backlit. Freightliner considers this a safety issue and will fix it free of charge. Call Freightliner (800-385-4357, have your VIN ready), and tell them of this problem (you may want to verify that they will fix this free, parts and labor). Have them send a new wire harness, AND INSTRUCTIONS, to your nearest Freightliner service center and have them make the modification, which takes about an hour - if they know what they are doing!. NOTE - This is covered under Freightliner Service Bulletin CSU 54-08.
-Submitted by Bob Cook

Some members report that they are having extremely rough shift when shifting down from 2nd to 1st gear (as when coming to a stop sign). Others report that, unexpectedly, their transmission shifts to neutral. Reportedly, the problem is with some solenoids in the control box of the transmission. (I believe this affects mostly pre-1999 D's, though not sure).

If your transmission goes into neutral by itself, the quickest way to reset it is to actually shut off the relay switch that is located in the upper vcr cabinet. This will make the transmission lose all of its driving memory and force it to reprogram and work properly again. There is an Allison update, but I do not know what it is. If you suspect that you are having problems, call Allison with your transmission serial number and see if your transmission qualifies for the solenoid changes.

Note - this is almost an all-day job!


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