Where to have TCM/TCU rebuilt? Or order a new one?

Covers engines and transmissions
Post Reply
Bilmac36
Posts: 75
Joined: Sun Oct 27, 2019 10:06 pm

Where to have TCM/TCU rebuilt? Or order a new one?

Post by Bilmac36 »

Hey Gents,
Been helping my cousin remotely trouble shoot his rig. As well he’s contacted a local Allison shop he trust. Reaching conclusion his rig’s issue is a temperamental (literally) Transmission Electronic Control Unit. Do you know of a current electronic repair facility, and/or site to order a unit from? He’s checked this business (see pix) but appears they are no longer in business.
By now many of you are full of questions about what has or hasn’t been checked. So I’ll explain, but responses to the initial question are appreciated. At this point I’m thinking some of the large salvage yards for a used unit may be the answer.

Ok, his tranny set up is essentially identical to mine. My rig is a ‘95 Continental, 8.3L, MD3060. Our tranny’s s/n are literally a few digits apart from each other and have the same shift pads. His rig is a ‘94 WB Vectra, 5.9L Cummins (1 Chassis, 2 House batteries.) So the issue at had is a temperature issue. During morning cold, say in 30’s rig will not start. No trans pad lights, no VIM relays latching, nada. Wait till noonish, 15-20 degrees warmer the rig fires right up.

Initial fault this past week, he was at tire shop getting ready to get his 6 year old front tires changed out when the rig would not start, some flashing lights in dash, and rpm gauge bouncing. Story here was he discovered the exciter and the rpm wires had come off of his alternator. He repaired those. But appears these broken wires may have induced other issues. Keep reading please (thanks!)

Using our excellent historical resources here (have read of Mel’s issues and repairs, Brett’s recommendations, Jim and John’s follow up comments in numerous others in the older blogs dealing with this issue.) To date we have verified battery voltages are good/excellent; tested the VIM 6 relays; replaced two dif’t solenoids (both appeared to have been worthwhile replacements as when shook they rattled;) verified two fuse links are good; replaced all 6 VIM relays with new ones; cleaned multiple battery contact terminal lugs; and replaced the ignition switch. Ok, some of these had been a need for and culminated with this issue.

The temperature issue appears to be reality as Groundhog Day has occurred daily for the last 5 days. The Allison shop tech noted he’d experienced a similar issue with his rig and had used his wife’s hairdryer to warm the TCM/TCU unit for several minutes with the positive results of the rig starting. So tomorrow morning my cousin will be verifying once again his rig doesn’t start, then follow the hairdryer steps to warm and see if then starts. Now we are back to my initial question, who repairs, where to buy?

I’d like to also ask if any of you have the schematics to this unit and are aware of what components may actually cause such a problem? I can do electronic component replacement down to the mini-soldering level and as long as we can get our hands in the components and the PCboards are single layer then I should/may be able to do the repairs.
Appreciate y’all taking the time to share your KSA’s.
R/Willie
‘95 Continental, 8.3L (mine since ‘99/‘00)
Attachments
E80EB2C3-99EA-4E46-98F2-CE661EB2A7A0.jpeg
E80EB2C3-99EA-4E46-98F2-CE661EB2A7A0.jpeg (88.58 KiB) Viewed 17681 times
4C4FFC5A-A954-4B57-B863-5449BD32DBDC.jpeg
4C4FFC5A-A954-4B57-B863-5449BD32DBDC.jpeg (197.97 KiB) Viewed 17681 times
r/Willie
'95 Safari Continental, Cummins 8.3L, Allison MD3060
Bilmac36
Posts: 75
Joined: Sun Oct 27, 2019 10:06 pm

Re: Where to have TCM/TCU rebuilt? Or order a new one?

Post by Bilmac36 »

Ok, looks like we found a place. Any of you untilized this family ran business? If so, what’s the good/bad/ugly? Thanks

https://www.transmissioninstruments.com/
r/Willie
'95 Safari Continental, Cummins 8.3L, Allison MD3060
TDJohn
Posts: 552
Joined: Sun Oct 27, 2019 11:34 pm

Re: Where to have TCM/TCU rebuilt? Or order a new one?

Post by TDJohn »

Bilmac36 wrote: Tue Mar 09, 2021 8:13 pm Ok, looks like we found a place. Any of you untilized this family ran business? If so, what’s the good/bad/ugly? Thanks

https://www.transmissioninstruments.com/
That is the place you want. Members of this group and members of other forums have used this place with raving reviews. They can guide you through the diagnostic process (it might be on their site) and they are very honest. If the TCM or the shift pad tests out ok, they send it back to you without charging you for an unneeded rebuild. You are probably aware, but just in case I will restate it. The TCM needs to power sources, one from ignition and one that constantly feeds the TCM. Also, check ground wires. Allison usually specs a direct run of both positive and ground, right from the batteries to the TCM, so if you have an intermittent ground it cam cause you this kind of grief.

I will attempt to attach an ignition circuit schematic from a Safari Beaver coach. His coach will obviously be different, but at least it will give you an idea of how the interlock logic works and how the TCM is powered.
I will also try to attach diagnostic instructions.
You have my number if you need extra help or have more questions.

_Allison Power Failure Troubleshooting Guide.pdf
(179.84 KiB) Downloaded 251 times
48667.pdf
Safari Beaver Coach Starting Circuit
(222.75 KiB) Downloaded 248 times
John
'95 Serengeti, Cummins C8.3-300
Allison 6spd.
wolfe10
Posts: 222
Joined: Sun Oct 27, 2019 4:12 pm

Re: Where to have TCM/TCU rebuilt? Or order a new one?

Post by wolfe10 »

Absolutely, contact John: https://www.transmissioninstruments.com/about/

This is what he does for a living.
Brett and Dianne Wolfe
Ex: 2003 Alpine 38'. Ex 1997 Safari Sahara. Ex 1993 Foretravel U240
Moderator, FMCA Forums 2009-2020
Chairman, FMCA Technical Advisory Committee 2011- 2020
Moderator, http://www.dieselrvclub.org/ (FMCA chapter) 2002-
Bilmac36
Posts: 75
Joined: Sun Oct 27, 2019 10:06 pm

Re: Where to have TCM/TCU rebuilt? Or order a new one?

Post by Bilmac36 »

John, Brett,
AS Always this team comes through! Greatly appreciate yalls input.
My cousin is calling them this morning. And with John's link to their pdf TS (which later went back and navigated to via their site) I think he will follow their TS'ing advice and see what he comes up with.
The coach did exactly as was speculated it would. Late last night after it cooled down he tried to start it, it flashed at him. He turned it off, used hair dryer to warm TCM/ECU and all was good. Then again same scenario this morning.
He's hoping to get with these folks and get a quick turn around, hopefully after he follows through with their TS steps. Both ours are the WTEC II. Evidently mine is early '95 from what I'm reading on their site.
I'll try to do a followup and confirm what his final fix is.
Again thanks,
Willie
r/Willie
'95 Safari Continental, Cummins 8.3L, Allison MD3060
Handlebar Jim
Posts: 9
Joined: Mon Oct 28, 2019 9:04 am

Re: Where to have TCM/TCU rebuilt? Or order a new one?

Post by Handlebar Jim »

Jim Hoerst
37' 1994 Serengeti

I was extremely pleased with everything about https://www.transmissioninstruments.com/
Rebuilt mine 4 years ago.
Bilmac36
Posts: 75
Joined: Sun Oct 27, 2019 10:06 pm

Re: Where to have TCM/TCU rebuilt? Or order a new one?

Post by Bilmac36 »

Thanks Jim. Appreciate the feedback.

Update: he got it started by warming up the TCM/ECU and finally did the diagnostic test. I believe at D2 it populated the 69-32 code which the Transmission repair site basically states to stop there and mail it in.
As an FYI to those who like to DIY down to the component level there is a YouTube video of a youngman showing what he found and his solder job to do the repair within the unit. My hat's off to the young fella as I've been there, done that.
Again, appreciate all the feed back.
r/Willie
r/Willie
'95 Safari Continental, Cummins 8.3L, Allison MD3060
Post Reply