Allison 2000 Service manual

[ewo1]

So we swapped the TCM and the fuse does NOT blow!!!!

Tested key on engine off and we now have the check trans light working again...

Now ... a test drive!

[ewo1]

Pre-mature success...here we go again...

So the fuse does not blow anymore that is confirmed but the check trans light does NOT come on when the key is turned and ...no shifting...

Next thing were gonna check is the cables pins them selves, making sure they are all seated properly in the connectors themselves and also the NSBU switch. I have been reading that they have a high failure rate due to excessive dirt and moisture.

Let's hope this stays simple....

[RolesvilleMarina]

Just confirming

Check trans light did a KOST (Key on self test)

But then you tried again and it now does NOT do a KOST?

that is odd

and this TCM is just one that you randomly grabbed and slapped in? Or was it programmed for the bus and it's engine?

I'm no guru, but is it possible if you just simply slapped in a random TCM that you have a programming issue?

This is the **** I basically did when I did my transmission swap, but my donor bus was same engine so I got away with it.

[ewo1]

Originally Posted by RolesvilleMarina

Just confirming

Check trans light did a KOST (Key on self test)

But then you tried again and it now does NOT do a KOST?

that is odd

and this TCM is just one that you randomly grabbed and slapped in? Or was it programmed for the bus and it's engine?

I'm no guru, but is it possible if you just simply slapped in a random TCM that you have a programming issue?

This is the **** I basically did when I did my transmission swap, but my donor bus was same engine so I got away with it.

Thanks for asking...
My helper incorrectly told me the Check Trans light did come on, it doesn't.

The replacement TCM did come from a 2002 DT466E, the tcm is also labeld for a dt466. The bus is a 2000.

The good thing is that the fuse does not pop anymore but I'm afraid we will have to check the wiring next.

It would be great if I could find someone with a kent-moore breakout box so I can test both TCM's... but I guess I'll just buy lotto tickets instead.

I'm new to all this tranny troubleshooting....
I was at first thinking maybe the NSBU switch might be bad, but then I was thinking the check trans light should come on.... and it does not.

[ewo1]

So an update on this saga...
The new (used) TCM that was obtained, turns out that it was only compatible with a 1000 tranny not a 2000.

We come to learn that the physical "Box" of the TCM is identical between the two trannies.

We called an Allison shop and they crossed checked the numbers on the TCM with the serial number on the tranny, confirmed...we were sold the wrong TCM.

The old one was sent out for repair, apparently it got fixed and is on it's way back to us.

We'll know in a couple of days if this bus is gonna roll or not!

Lesson learned here...call an Allison shop and verify the numbers before you spend the money!

[ewo1]

Ok so the bus is back on the road...
NO more Limp mode!

We are guessing that maybe when the batteries died, twice, and we hooked up the battery charger we only pulled the one fuse which is actually the ECU fuse as we found the fuse for the TCM at another location outside of the battery box.

It was either low voltage cranking or the charger itself that probably fried the TCM causing any fuse put it to immediately pop!

So now we know there are 2 fuses...next time batteries need charging the battery cables are coming off, after pulling the fuses of course.

[Rucker]

Quite a read! And quite a journey you went through.

Kudos for doing it systematically and keeping us all in the loop each step of the way. We learn together.

What's your biggest takeaway from the experience? I'm torn between 'keep the bus charged up' and 'don't jumpstart with a massive charger'.

[ewo1]

What I learned, 1) disconnect the batteries before charging, 2) don't use the charger to "Jump" the bus and 30 know where those fuses are, don't wait to figure it out later!