TCM failure Allison 4000

[Darren A.]

I’m having issues with my transmission shifter.  While driving my shifter pad shutdown then transmission goes into limb mode gear 1C.  In the engine compartment  there are 4 fuses on the frame.  I attached the picture for reference.  Once I’m able to pull safety pull the RV over and keeping the engine running, air brakes on my wife sits in chair. I go to the the engine compartment pull out the first fuse on left and the shifter pad comes back on and we continued on.   This has happened twice!  
I have it in the shop for repairs after locating the TCM the technician indicated he was unable to communicate with the TCM.  He believes that he detected a burnt smell.  He also stated that back in 2001 - 2005 there were issues with TCM?  He’s reluctant to order new TCM at this point without full diagnosis but can’t pull codes.  
Again this is for 2004 Holiday Rambler Navigator.  I would appreciate feedback.  Thank you all 

[vito.a]

Good job finding and resetting that fuse!

There is a direct wire from the battery bank to the transmission TCM.  Not sure, it may be the one you are  resetting.  I would start by finding it, cleaning the terminals, and changing the fuse. 

I would also check and clean the TCM and transmission shift pad ground wires. 

I like to use DeOxit to clean terminals.  

https://www.amazon.com/Hosa-D5S-6-DeoxIT-Contact-Cleaner/dp/B00006LVEU/ref=sr_1_1?dchild=1&keywords=deoxit&qid=1629993103&sr=8-1

Hope you find it! 

Edited August 26, 2021 by vito.a

[Art Perrone]

In a similar situation, I brought the TCM to an Allison dealer.  They were able to get a look at the programing and values in the TCM.  The TCM is easily removed from the coach. No special tools are required.

Good Luck,

Art Perrone

[Darren A.]

The wire runs from the battery disconnect switch to a fuse then to I assume to the VCM. The fuse holder (second from left) is crimped together with the first fuse holder again from the battery disconnect switch. Each second wire goes toward the engine area first fuse again I assume to the VCM, the second somewhere else.  While using a 12 volt test light the second fuse from the left only lights up from one side with the fuse removed which is normal right?  One side positive the other side ground?  The first fuse holder while using a test light with fuse removed both sides are hot, pretty sure that’s not normal?  This is the fuse I assume goes to the VCM.  Even with the battery disconnect switch off there’s still 12volt constant on both sids of that first fuse holder, that can’t be right? 
 

Vito I asked them to trace that wire, check TCM and the shift pad ground wires.  Hopefully it becomes a simple fix!

[Michael Powell]

following

[Darren A.]

The shop overnight the TCM to Allison to run diagnostic.  I will keep the group updated once I hear back from them.  

Does anyone know about issues with TCM years 2001 - 2005?  The shop telling me that’s what Allison reported to them 

[jacwjames]

We lost our TCM in 2013, this was on a 2002 Windsor with the 3000 transmission, if that makes a difference. 

My wife was getting ready to go on a trip to NY for a dog show.  I'd taken the rig to get fuel and parked it in front of the house to hook up the Jeep.  Once I got the Jeep hooked up went to start the rig to check lights, brakes etc and there was no power to the dash or the shifter pad.  I checked all I could and ended up having to have the rig towed to the Allision shop, they refused to send a tech out saying they were short handed. 

I was getting ready to catch a plane going to Spain and just talked to the tow truck driver as he was pulling into our subdivision.  Wife had to deal with it from there.  The ended up diagnosing a bad TCM, luckily they had one at a shop ~100 miles away that my wife actually went and got, they programmed it and she was on the road the next day, making it to the dog show just in time to had the dog to a handler for him to show.  (she didn't win).  Cost for all of this was ~$3500.  If you have time you can get yours repaired for far less then this.  Still have the old TCM so if mine starts acting up I'll send it in for repair. 

Good Luck, keep us posted.

 

[Darren A.]

I will Jim and thank you

[Darren A.]

Update the repair shop replaced the TCM but still unable to communicate with the RV to receive codes.  They test drove the unit 3 times no issues with shifting.  However I’m concerned that they still don’t know what caused the shifter to shutdown in the first place.  I’m concerned it would happen again.  I desperately seeking any other advice

[Ivan K]

Where is he plugging into? Our 4060 has a separate diagnostic connector beside the steering wheel under dash.

[Darren A.]

You are correct, I knew that as well.  I asked the technician if he tested from that location?  He said he did.  It makes no sense to me the TCM was sent out for testing they said it was faulty.  It’s been replaced and I have the old one.  

[Ivan K]

I recall seeing diag fuse in our FRB, maybe more than one. I know there is one for the engine diag, wonder if for the tranny too.

[Darren A.]

Doing a lot of research here is it possible the VIM has bad fuse or relay?  I just read on another social platform that the VIM powers the ECU which would make sense right?  Maybe why they cannot communicate with unit?

[Ivan K]

True that the ECU gets power through VIM and ignition but I doubt your transmission would work without it. If the diagnostic port is a 12 pin type as mine,  only 4 pins are used, 2 for power 2 for data link. The power could be checked between pins A and H. Should be present with ignition ON. Allison also requires different reader cartridges for the interface based on the ECU version, that might be part of the problem. But if you just wanted to check for codes, the touch pad should do that. I bet you know that already and just want to have the diag port working.

[jacwjames]

On my 2002 Windsor I have 3 separate fuse holders in my rear run bay that hold the 7 fuses for the Eng, Eng diagnostic, transmission.  Yours may also have these in another spot. 

In the Cummins Quickserve site there is an electrical diagram showing the interaction of the ECM and the chassis, there is also some interaction with the transmission.  It is under the "Service" tab and listed as wiring diagrams.  It does show 5 of the 7 fuses.