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Epollan2000 · 09-18-2020, 11:55 AM

Hey guys,

I recently bought a 1999 35’ Airstream Cutter. It has a Cat 3126b engine and a Allison MD3060 trans. It’s my first motor home so I drove it on several short trips to be sure that I had everything working properly. I put about 300 miles on it. Then I loaded up the family and we took our first trip. We was approximately 300 miles from home, sitting in traffic and I noticed the speedometer started jumping all the way across. When I pulled away from the red light, it was stuck in first gear(would not shift). I pulled over and turned the truck off. Everything reset and no issues rest of the trip.

Since returning home, it sets a light on the dash and stops pulling. I check the codes and get a output speed sensor code so I installed a new sensor. Now I get OL 70 when I first crank it and as soon as I put it in gear I get OL 95 and the truck stops pulling. It also sets a light on the dash.

I have tried to clear the codes from the push button pad but they will not clear. Any suggestions?

Thanks,
Eric

wolfe10 · 09-18-2020, 12:00 PM

OL 70 and OL95 are NOT diagnostic codes. They are oil level readings:

OL70 is sump temp too low for accurate reading.

OL95 is "oil level sensor failed".

To get diagnostic codes, ignition on, engine off:

Push up and down arrows TWICE (once to bring up OL, the second to being up d-1, etc.

Let us know what you find.

Epollan2000 · 09-18-2020, 12:03 PM

I get d1 22 16. But that was before I changed the sensor. And I can’t get the code to clear.

Epollan2000 · 09-18-2020, 12:07 PM

It immediately throws OL 95 as soon as it stops pulling. It does not show that code prior to locking out of gear.

wolfe10 · 09-18-2020, 12:13 PM

Bad voltage to the Allison ECU can cause all kinds of issues.

It's "run circuit" is supplied by an "ignition hot" circuit. So, when this happens, do any other things that normally only work with the ignition on not work-- dash HVAC fan, for example.

If so, check the ignition solenoid/ignition switch and wiring between them.

Epollan2000 · 09-18-2020, 12:15 PM

There doesn’t seem to be any other issues. I did notice when I cranked it up today, the engine rpm’s were not constant. They varied a little until it warmed up. But that’s the only unusual issue I have noticed

wolfe10 · 09-18-2020, 12:28 PM

Call John-- this is what he does for a living:

https://www.transmissioninstruments.com/

Epollan2000 · 09-18-2020, 05:08 PM

So I called Transmission Instruments. John wasn’t in today. Talked to another tech. He ask for readings from certain pin outs. All readings were fine. We cleared codes and immediately got the output speed sensor bad code. He suggested that these trans have quite a few bugs in the wiring. So I we wired the output all the way to the ecm. Truck only moved about 5 feet before speedo went to wide open and error code popped up which disables the trans until a key cycle. I’m kinda at a loss. Does anyone have a wiring diagram for the md3060 with wtec3 controls?

glasman98001 · 09-18-2020, 06:31 PM

You said u rewired,,,,I take it u ran a new wire from output speed sensor to the ecm,,,did u use a signal wire or just a regular wire? must be a signal wire...I see ur a 1999 model,,,u will be looking forward to sending ur unit to John just because of its age,,,mine lasted 23 yrs and only 50x miles...keep posting and u'll get help..

Epollan2000 · 09-18-2020, 06:55 PM

Original wires were not shielded They were regular wires that were twisted. I replaced with like wires. Ohm’d the same when done. Same exact problem as before I ran new wires.

RKins · 09-23-2020, 08:54 AM

Maybe this troubleshooting manual can help?

Epollan2000 · 10-01-2020, 04:11 PM

So I have gone through the troubleshooting guide and this is where I’m at. I have checked all power supplies and everything has the proper voltage. I removed the tail section of trans and verified that the reluctor wheel was tight for the speed pick up. I have run 2 new twisted wires to the speed sensor. I have talked with John at transmissioninstruments. He doesn’t think it’s a ecu issue. Here’s my latest find. I can remove the speed sensor from the trans and the erratic speedo stops. I can put any one of the 3 new sensors on it and it’s normal. As soon as I put any one of them in the hole, speedo goes nuts. I’m at al loss for what’s causing this. The reluctor wheel is not moving when in gear and stationary but speedo goes crazy.

Epollan2000 · 10-01-2020, 04:15 PM

Oh. And I have shimmed all sensor s outward anywhere from .0010-.0065. Any nothing effects the erratic needle.

Epollan2000 · 10-01-2020, 09:58 PM

Ok. So the plot thickens. I couldn’t stop thinking about a electromagnet pulse getting on the system some how. So I go outside to take the hot wire off the alternator. It’s late so I turn on the lights inside. Before removing the wires I started the truck to prove the problem. Crank the truck and there’s no problem. I was confused. Double checked everything. Stopped to think what has changed. Turned the interior lights off from the master switch and problem came back. Turned them back on.... problem goes away. At least I have a direction to look in now.