Community Forums

Skyboy · 03-19-2025, 08:11 PM

Hello everybody! New guy here. Trying to understand what I have and how to fix it. Long list of questions, but I will do my best to do be short.

1995 HR 40ft 300-Cummins with MD3060

Before our trip to Arizona in February transmission refuse to upshift and stuck in first gear = Code 2511

Talked to John Kopalek = resistance on output speed sensor right on the transmission is 300 ohms = upfront right at the controller is about 300 ohms as well.

He suggested before spending any money to try replacing the wire between sensor and the controller and see what happens. Magically after replacing the wire with speaker wire that I had on the shelf transmission start working normally.

Next day we were going to Arizona and from very beginning I noticed that transmission temperature on the gauge is "0". Speedometer speed doesn't correspond with GPS speed and sometimes higher or lower by about 10 MPH. RPM on dashboard is jumping up and down as well. Sometimes transmission was shifting absolutely beautiful, but sometimes very harsh.

We made 4000 mile round trip and got home without any problems.

I ordered 2 new speed sensors with turbine sensor and shielded wire. Planning to replace it when I get some time.

I would like to know where dashboard get transmission temperature from? As well as RPM and speed?

Maybe good idea to pull more wires for more sensors? Have anybody done this before? How many wires should I pool?

Any information would be appreciated! Thank you!

Skip426 · 03-19-2025, 10:09 PM

What chassis is your coach built on ?

My 3060 the sump temperature sensor is internal on the transmission valve body ,BUT !! , some chassis manufacturers added their own sensor in the cooler lines.

SafariBen · 03-19-2025, 10:50 PM

Same engine and trans in a 95 Safari: the tachometer was driven by the alternator. The dash trans temp is from an external sensor, on the trans line to the cooler.

I believe the speedometer signal comes through the TCM, or possibly directly from an Allison sensor, but don't quote me on that.

I would focus on the alternator IF the problems appeared at the same time. Double check the alternator voltage at the alternator, at the battery isolator, and voltage drop between alternator and battery, positive and ground, and voltage drop to the front. Run some test leads and check all those again under way also if you have to. OR, just add some more grounds up around the dash ground bus.

Find the trans sensor and short that wire to ground, if the gauge goes to high with the key on, then the gauge and wiring are fine. Possibly just a bad wire or connection, not likely to have anything to do with the shifting or other issues.

SafariBen · 03-20-2025, 07:04 AM

Have you checked the trans fluid level with the shifter? That will not only confirm the level, it will confirm that the TCM temp sensor is working. Try to check when you first start the engine, and then after a drive, the first check should give you a code for too cold, then get the correct oil level when hot.

Skyboy · 03-20-2025, 07:27 AM

Quote:

Originally Posted by Skip426

What chassis is your coach built on ?

some chassis manufacturers added their own sensor in the cooler lines.

It is Spartan Mountain Master 2242.

I will look for external coolant line temperature sensor. Thank you!

Skyboy · 03-20-2025, 07:42 AM

Quote:

Originally Posted by SafariBen

I would focus on the alternator

We have 600 Ah house batteries and no solar panels yet at this point. Hydronic floor heating connected to diesel boiler. When Heating is working, it's only taking approximately 200 W.

Every morning when we all done walking the dogs, showers, breakfast, microwave, hairdryer = batteries down to 20% approximately.

After 8 - 9 Hr drive batteries usually gets charged back to 90% or so. That is telling me that I am getting steady 50 A from my DC to DC charger. So, I made conclusion that nothing wrong with alternator.

But this is completely new world to me, and I could be wrong.

Skyboy · 03-20-2025, 07:46 AM

Quote:

Originally Posted by SafariBen

Have you checked the trans fluid level with the shifter?

I had absolutely no idea that we can do this. Thank you. I will try that when I get a chance.

However, when I change oil and filters, pretty sure I have a correct fluid level.

SafariBen · 03-20-2025, 07:58 AM

Quote:

Originally Posted by Skyboy

I had absolutely no idea that we can do this. Thank you. I will try that when I get a chance.

However, when I change oil and filters, pretty sure I have a correct fluid level.

So you know your transmission better than Allison? not much to say then is there. Good luck with running the new wires.

Skip426 · 03-20-2025, 08:45 AM

I believe your Allison electronic control system is WTEC II ( World Transmission Electronic Controls ) and the main controller will look like the one in this picture.

I have a file on diagnostics for the system ; but it's too large to post in the forums .

Skyboy · 03-20-2025, 08:49 AM

Quote:

Originally Posted by Skip426

I believe your Allison electronic control system is WTEC II

Yes, that is correct. I will send you my personal email. Thank you!

SafariBen · 03-20-2025, 08:51 AM

first, find the instructions for checking the oil level from the shift pad, and do that cold when you first start the engine, and again after driving.

second, check the alternator voltage. The tachometer is typically driven by the alternator, and that's the easiest thing to fix, so should be the first to check. The Allison controller should run it's own power wires directly from the battery, but it's still possible that poor grounds or dirty power are affecting the speedometer or tachometer and/or the TCM.

Only after diagnosing the tachometer would I look into the Allison troubleshooting manual, it's easy to find online, but very lengthy.

Skyboy · 03-20-2025, 08:56 AM

Quote:

Originally Posted by SafariBen

first, find the instructions for checking the oil level from the shift pad, and do that cold when you first start the engine, and again after driving.

second, check the alternator voltage. The tachometer is typically driven by the alternator, and that's the easiest thing to fix, so should be the first to check. The Allison controller should run it's own power wires directly from the battery, but it's still possible that poor grounds or dirty power are affecting the speedometer or tachometer and/or the TCM.

Only after diagnosing the tachometer would I look into the Allison troubleshooting manual, it's easy to find online, but very lengthy.

Thank you for detailed explanation!

dons2346 · 03-20-2025, 05:02 PM

"first, find the instructions for checking the oil level from the shift pad, and do that cold when you first start the engine, and again after driving."
I don't think an accurate reading can be had from a cold transmission. It has to be at operating temps to get a reading

wolfe10 · 03-20-2025, 05:45 PM

Quote:

Originally Posted by dons2346

"first, find the instructions for checking the oil level from the shift pad, and do that cold when you first start the engine, and again after driving."
I don't think an accurate reading can be had from a cold transmission. It has to be at operating temps to get a reading

CORRECT!

The shift pad fluid level only works after the transmission is fully warmed up. Do it after driving some highway miles.

You can use the dipstick to check it both cold (lower and also less accurate) and then again with it warm. But Allison prefers the shift pad check.