Allison problems


dbarton291

Senior Member
OK good! While you're checking the trimmer valves, also take a look at the trimmer regulator. also take a look at the trim boost accumulator if it has one.
 

DavidV

New Member
Re: Allison problems

I have a 1993 American Eagle with MD3060 transmission and have the exact same problem. I worked on it all day yesterday trying to trace out wiring, etc. If I knew where any of this equipment (ECU, TCM, etc) was located, it would make things easier. I have all of the manuals and books and none show where the ECU is at and I'm not even sure what a TCM is. Having been an electrician by trade, I believe there is a loose ground somewhere. When I turn the key on, the shifter will flicker a little and then go out with no display except the "Do NOT Shift" light is on. If I wait and come back in ten minutes, the shifter will light up with an "N" for about 3 seconds and then go out again. After about three hours of looking at connections, etc., I turned the key and all was normal. Then I put it into Reverse and the shifter went blank and the "Do NOT Shift" light came on. Of course, did shift it back to Neutral and turned everything off. I went back 30 minutes later and it all worked again. This time it even shifted without going out and I managed to back it out and get it turned around and parked where it has an electrical source to plug into. Everything worked perfectly for many more attempts and I quit for the night thinking it might have been a ghost or something! Went out this morning and it worked great and I got it started and the air pressure built up. Just as the air pressure turned the buzzers off, the shifter started to flicker a little and then went off and on and the OFF! There are no diagnostic buttons on my shifter to even get a code and if there was a code, I wouldn't see it because the shifter is blank and appears to have no power. The nearest RV shop is over 50 miles from me and I am on a fixed income with very little cash on hand. Does anyone have a 1993 American Eagle, Cummins engine, Allison transmission, that knows the location of the ECU, etc.? I sent Spartan (the Chassis Manufacturer) an e-mail with the chassis model & serial number and ten minutes later, they sent me the wiring schematic of my motorhome. Now that's service! Unfortunately, it ends in with an arrow that says "ECU" that direction. I guess the chassis maker didn't wire the transmission.
I have a 1993 Pace Arrow 250hp diesel with MD3060 transmission and have almost the same problem. Has anyone had the same issues and if so, what was the fix? Any help with this problem would be appreciated. Thanks
 
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DavidV

New Member
I have a 1993 Pace Arrow 250hp diesel with MD3060 transmission and have almost the same problem. Has anyone had the same issues and if so, what was the fix? Any help with this problem would be appreciated. Thanks
After reading about several people having this same issue, I was fairly sure the trouble was in my ECU. It turned out that was correct. I sent the ECU to Transmission Instruments in Flower Mound Texas 1-866-439-9779 and had the ECU repaired. They did a great job by the way. I got the unit back, installed it and yea! fixed! Thanks David V
 

Johnwj

New Member
I recently brought a 1994 diesel pusher (1994 contentinal 3.8 with push button allison tranny). We went to the lake and the next morning the do not shift light was on and it would not go into gear. Finally was able to hit the drive the same time as the engine started and got it home. I went out several times and started it and it worked fine then the next time the do not shift came on the display on the push button panel flickered a little. I took the unit out and had it checked out and was told it was fine but there was a code for a power interuption. Put it back in and it worked great. I went out and drove it around yesterday all was well. Went out this morning and it is dead there is no power to the push buttons not a fliker. Sometimes in starting the engine I can turn the key but it does nothing. If I do it several times it starts. My senses tell me its a relay or something.

Any thoughts or ideas would be appreciated.
I agree with the first reply you got. Low Power to the TCM will give you this exact problem. After 2200 miles of intermittent similar problems, two towing jobs and Two service calls, Technician found low voltage on the IGNITION ON line. could not find the point of loss so he wired around it and Waa Laa, next 35000 miles were trouble-free (from this problem).
 

Jan Nelson

New Member
I own a 1999 Beaver Monterrey, 30' powered by a Cat 300 paired to an Allison MD3060 6spd transmission. I want to help others who run into an issue where the shift selector shows an error condition, or nothing at all. This tends to happen after swapping out chassis batteries and is almost always due to either reconnecting three wires in the battery box incorrectly or a bad ground.

Always take a photo of the wiring before disconnecting anything (ask me how I know). In particular look at the 10 gauge wires connected to positive and ground and make certain that you reconnect them properly. In the harness in my coach they are the same color, so no indicator of which is positive and ground.

Next look at the condition of the connectors, clean them up, possibly replace them if the wire is breaking down at the connector or other corrosion exists. If you havce a flakey connection, it WILL lead to problems!

That all being good, also check for the VIM and ECU power fuses which are also likely in the battery box. If these also check out, then find the location for the ECU and VIM. In my coach they are located in behind an outside door, driver side, front along with terminal blocks for a lot of the coach wiring. There are two fuses in the VIM, check those out as well and make sure they have power.

OK now that you have all this confirmed or fixed, and no change at the shift selector, you might wonder if the ecu is bad, and what your options are. I strongly recommend that your next step is to go to the Transmission Instruments webpage I am linking here and carefully follow the troubleshooting steps on the page:

https://www.transmissioninstruments.com/troubleshooting/

I found this site and thought that even after using the guide that my ecu might be bad. Being stuck outside Ft. Worth, Texas on a road trip, I was willing to do just about anything to get my coach running again. I called the company, reaching the owner:

John Kopalek
Owner
Transmission Instruments
972-353-8286
www.transmissioninstruments.com

It turns out that he was physically located about 45 minutes from where I had my RV towed. We agreed that I could bring my ecu to him to test out. John has created the test equipment to quickly determine if the ecu is good or bad, as well as the shift selector. Within minutes, John convinced me that the ecu was good, then spent about 45 minutes teaching me about the interfaces (three harnesses connect to the ecu) and how to test the pinouts on them to find the problem. This info is laid out in the link above, read it!

John also had a WTech III shift selector in inventory, so I bought it from him to assure I had a good one at hand. Armed with the knowledge of how to test the system, and one good part under my arm, I headed back to the shop that had my coach. The shop owner was very gratefull to work with me on the problem, given there is no schematic online that (nor was there one in my manuals) helped us isolate the problem of no display on the shift selector (and therefore, no start from the ignition switch at the driver seat.

Knowing that the ecu was good, we focused on the pinouts of the harness that supplies power to the ecu. This power comes from the chassis batteries, is not switched, so take care with your testing. We found that there was power where we expected grounds on two of the pins, which sent us back to the battery box. It turned out that one of the 10 gauge wires had "shortened" by falling back, through a hole in between the battery box aqnd the engine compartment, making it appear that it only fit on the positive terminal of the back battery. After tracing it into the engine compartment, and finding extra length there, we pulled it back into the box, and reconnected to the negative terminal, along with the other 10 gauge ground hooked up there. Now we had ground on the pins as expected. I had that wrong! (always take photographs of the wiring before disconnecting chassis batteries).

But, we still had no display on the shift selector. With everything checking out to the ecu and the VIM, it was time to look at the ecu outputs. They looked good as well, so we decided to assure we had a good ground between the ecu output and the selector. We hacked the harness at the ecu out connector and moved the ground wire with an extension to ground at the terminal block adjacent. Turned the key on, and everything lit up, the engine started and shifting was enabled.

The key here, and this not just from my personal experience, but from John at Transmission Instruments, is that you MUST have a solid ground and that this is #1 problem most of the time. Whether from rodents, from a corroded connection, or because you are a bit of a knucklehead like me and do not photograph the battery connections before swapping batteries, a bad ground in the ecu circuit will cause failure.

After we fixed the two issues I had of an incorrect connection AND a bad ground somewhere in the harness, I took the now-unneeded spare shift selector I had purchased from John and put it in the mail back to him, expecting a core charge refund. John is a saint. Not only does he test the ecus for free, he refunded my entire cost of the shift selector! He wound up charging me nothing for his expertise. I strongly recommend that you use John if you ever have suspected ecu issues.
 

paddak

New Member
I have 2000 fleetwood discovery transmission problems.
check trans light on dash.
no crank , and no shift pad selector light
happened after changing the starter batteries.
I have 5 volts at shift pad..
 

Jan Nelson

New Member
I have 2000 fleetwood discovery transmission problems.
check trans light on dash.
no crank , and no shift pad selector light
happened after changing the starter batteries.
I have 5 volts at shift pad..

This is almost always due to miswiring the required voltage and ground in the battery box back onto the starter batteries. These connections are required to assure that the controller has an uninterrupted current supply, whether the alternator is working or not. The symptom you describe is identical to that I recently had to troubleshoot using this guide:

https://www.transmissioninstruments.com/troubleshooting/

I was convinced that I had everything correct, but ultimately found that I did not have a solid ground connection for the ECU power off the starter batteries. After I moved past my denial phase, it became a simple problem to troubleshoot and overcome. Happy hunting!
 

WJOMullins

New Member
"That all being good, also check for the VIM and ECU power fuses which are also likely in the battery box. If these also check out, then find the location for the ECU and VIM. In my coach they are located in behind an outside door, driver side, front along with terminal blocks for a lot of the coach wiring. There are two fuses in the VIM, check those out as well and make sure they have power."

Made me think of fuses and I went back and checked them all again. Replaced a burned on and BAM she fired right up! Thanks, Jan Nelson!!!!
 

SteveV

New Member
Hello, I have a 94' American Eagle, 8.3 Cummings / 6 spd Allison. Looks like I'm having the same issues.

While I was out of town, this problem presented itself as a more intermittent problem. No start, no shift light on, blinking indication on the shift panel. Sometimes the indication stayed steady, and I would have a start. So made it home from there, but now it seems to be a hard fail.

I checked the fuses in the VIM, and the connections best I could, but the same problem persists. [At least I'm home in my own driveway].
Did anyone post what the fix ultimately was? I just don't want to buy a computer for troubleshooting.

Attached photos and a link for a short video of the display.

Any help would be greatly appreciated.

Thank you.

 

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SteveV

New Member
For some reason, the latest posts [anything North of 2014] was hidden until I uploaded my post looking for more information. Then I saw this little message that said hey there's more posts, do you want to see them? Yup! and that brings me up to 2020. I'm reading through them now.

What a pain in the rear this problem is! But at least I'm broke down in my own driveway. This time! lol
 

SteveV

New Member
So thank you to those here that provided the contact information for Transmission Instruments. They were very helpful and walked me through obtaining the diagnostic fault codes.

For those that do not know, I post the procedure here:

  • Ignition on. Display illuminates.
  • Use a Q-Tip or something similar in the hole directly below the "mode" button, and press. There's a hidden button there.
  • There might be more than one code. The unit holds up to five. First code will start with "d" "1" and so on to "d" "2", etc. if any. Press the same button again until returning to the "N" "N" display.
See the video below.

The folks at Transmission Instruments said the symptoms I had could be temperature sensitive. Fails on cold mornings, then start on warm afternoons. That's exactly the problem I have. Was 30's/40's in Flagstaff in the morning trying to start and then failed. But was 90's in Phx a few days prior. Now the same thing here in NC, 30's in the am won't start nor power up the display, 70's in the PM, all good.

They stated that's actually a rather common problem.

Crazy!

The fault code I have is d1: 69 32 - internal ECU fault. Nothing in the harness or external would cause that.

So next step, remove the unit [ECU is one with the gear selector] and sending it to be repaired, about $500-$600 plus shipping. Just glad I was in my own driveway now.

John Kopalek
Owner
Transmission Instruments
972-353-8286
www.transmissioninstruments.com

I'll post on the hopeful success when I get it back and installed.


 

SteveV

New Member
Follow up from my prior post regarding the outcome of sending the ECU to Transmissioninstriments. Problem FIXED!

Removal of the ECU unit was rather easy. I would use a sharpie to identify which connector on the back is either Top or Bottom as they appear to be interchangeable. Not likely to mix them up due to how the harness naturally runs, but your application may differ.

Shipped the unit out on Friday for a Monday delivery $120 FedEx. Transmissioninsturments called me Tuesday, stated the unit was repaired [Bad power supply], and the unit was on it way back. I had it back Weds afternoon, reinstalled Weds evening, everything worked great, problem solved.

I would highly recommend Transmission Specialists.
 

King Tuck

New Member
Greeting all
I have a 2015 class A TIFFIN Allegro RED w/ a Cummins 340 and Allison Trans.
When we arrived home from the last trip in October (in a driving rain), I discovered after unhooking the tow vehicle The transmission did not want to go into Drive. Instead of 61 showing on the select monitor i got a 6N and THE SHIFT INHIBIT light came on. It would go into Reverse with no problems.. After several tries and then going from Reverse to Drive it went into gear.
Does anyone have any ideas about this. I did take it to a shop where they found no codes but didn't know very much else. I'm looking at connections at or around the transmission. Anyone have any ideas ???
 
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