Electrical transmission issue Allison 3,000 pts cat c7 check trans abs range inhibit

[TheBlueBirdExpress]

Allison 3000 PTS 6 speed tranny from ‘09
150k mi. Well maintained by school district. We owned since Jan. Driving well, no tranny issues, since conversion completed 2 weeks ago.
*yes we have fluid and no, there’s no random tools in my tranny from the last maintenance🙄*
Allison tech at Kenworth in Jackson TN, working for 20 years, says he never seen something like this. One active fault code for fluid pressure sensor on circuit 2 having low voltage. Tons of other random fault codes, none active, none consistent. All while driving. While off, Allison computer program (not JPRO) reads code J1939 (see photo below regarding dual data link) Got range inhibitor coming on and locking us in neutral every 5 miles or so. Turn off and restart ignition allows another 5 miles driving. High rpm and low speed/low gear allows farthest mileage.
All tranny wiring plugs are clean. No ground faults for chassis ground.
Any ideas? We’d love to get out of TN and back to NH before our temp plates run out on the 10th. It’s a 12k tow on a flatbed to get home.

[ewo1]

I wish I could be of some useful help but all I can offer up today is this link to a doc site that has quite a few troubleshooting manuals on the allision 3000-4000 series transmissions.

http://docs-diesel-data.xyz:8080/Hea...4000%20Series&

I would download all the docs and save them as this site changes quite frequently.

On a similar topic though, on my MD3060 I did have a no start issue that was caused by a "High resistive open" that was located on one of the connectors. You could not see it by a visual inspection. I got lucky, when I tugged on the wire, it pulled right out of the backside of the connector.

https://www.skoolie.net/forums/f33/m...nel-24837.html

Post #2, you will see the broken wire.

I hope you find something in one of those manuals!

[TheBlueBirdExpress]

Originally Posted by ewo1

I wish I could be of some useful help but all I can offer up today is this link to a doc site that has quite a few troubleshooting manuals on the allision 3000-4000 series transmissions.

http://docs-diesel-data.xyz:8080/Hea...4000%20Series&

I would download all the docs and save them as this site changes quite frequently.

On a similar topic though, on my MD3060 I did have a no start issue that was caused by a "High resistive open" that was located on one of the connectors. You could not see it by a visual inspection. I got lucky, when I tugged on the wire, it pulled right out of the backside of the connector.

https://www.skoolie.net/forums/f33/m...nel-24837.html

Post #2, you will see the broken wire.

I hope you find something in one of those manuals!

I’ll check it out thanks! Ya we are thinking it may very well be some corrosion. Definitely possible censor but it’s strange just how manny codes it’s throwing, this list I showed is after it was cleared twice and every time it’s new codes.

[TheBlueBirdExpress]

Originally Posted by ewo1

I wish I could be of some useful help but all I can offer up today is this link to a doc site that has quite a few troubleshooting manuals on the allision 3000-4000 series transmissions.

http://docs-diesel-data.xyz:8080/Hea...4000%20Series&

I would download all the docs and save them as this site changes quite frequently.

On a similar topic though, on my MD3060 I did have a no start issue that was caused by a "High resistive open" that was located on one of the connectors. You could not see it by a visual inspection. I got lucky, when I tugged on the wire, it pulled right out of the backside of the connector.

https://www.skoolie.net/forums/f33/m...nel-24837.html

Post #2, you will see the broken wire.

I hope you find something in one of those manuals!

The link is sadly no longer active

[ewo1]

Originally Posted by TheBlueBirdExpress

The link is sadly no longer active

The site goes up and down alot but it is still good. Been using it for months now!

PM you email address and I will send you what I have.

[ewo1]

Originally Posted by TheBlueBirdExpress

I’ll check it out thanks! Ya we are thinking it may very well be some corrosion. Definitely possible censor but it’s strange just how many codes it’s throwing, this list I showed is after it was cleared twice and every time it’s new codes.

It probably throwing crazy codes due to an unstable power or signal source...aka a high resistive open, not a short or ground, maybe?

I layman's terms, a high resistive open occurs on a normal connection/splice where the wire has been corroded to the point that barely enough current can flow through it.

Best example, remember what static scratches and pops used to sound like on the old ma bell wired telephone lines!

Perfect example, sound /current would flow but with serious restriction.

[ewo1]

Originally Posted by TheBlueBirdExpress

The link is sadly no longer active

I just tried this link...it works!

http://docs-diesel-data.xyz:8080/Hea...uck%2FAllison&

try cut and pasting if clicking on it is unsuccessful.

[Booyah45828]

Check powers and grounds, check data wires for corrosion or chafing. Check terminals in the tcm and engine ecm for corrosion or damage.

Phantom codes are always tough to troubleshoot. Typically the problem is intermittent because what's causing it to happen is intermittent as well. This is compounded because allison tcm issues and failures aren't unheard of either.

Is reference voltage low on the pressure switch for circuit 2? Or is signal return actually low?

Good luck.

[TheBlueBirdExpress]

I believe the pressure switch is internal and we don’t think that one sensor or switch would be causing ransoms codes to pop up each time. This added with the fact the Mecanic and I have found no corrosion or apparent worn wires or wire harness seems to lead us in the direction of the tcm. The only external plugs are the main wire feed to everything internal and the engine speed sensor as well as the transmission speed sensors

Which btw if anyone is having problems those two sensors are the same and can be interchanged just to see if it make a difference or even to make it possible to get to ones destination. That’s a tip from the school dep mechanic we bought our bus from.

The computer is reading the continuity of all wires and the data link as ok so we have not gone into fully tearing apart the wire harness as this would also waste a lot of time.

With the shipping and manufacturing delays sensors and computers are basically all on back order and most places have in know lead times.

I called a lot of places and I happen to be very lucky. a certified Allison dealer only one hr away has the tcm, they will program for me tomorrow.

Btw got the tcm Base # of the back of the unit Beas 29545527 but now goes by 29551869.

Very hard to come by, ideally I would take a tcm out of the exact same bus but a known good one to test if it solves the problems but I don’t have that luxury. I have to get back 1300 miles by the 10th my temp plates run out then.

Hopefully this is indeed the problem and we fix it tomorrow with the freshly programmed unit! Otherwise I’ll have an extra for sale lol
Tomorrow

[TheBlueBirdExpress]

Ya makes A lot of sense. Only problem is that should theoretically show up on the computer and now that they have the computer running with the correct patch we are showing good power and continuity through all the wire systems. See my last post post for more thoughts and details. I appreciate it!

[TheBlueBirdExpress]

Originally Posted by ewo1

I just tried this link...it works!

http://docs-diesel-data.xyz:8080/Hea...uck%2FAllison&

try cut and pasting if clicking on it is unsuccessful.

It required a password and username?

[TheBlueBirdExpress]

Originally Posted by ewo1

It probably throwing crazy codes due to an unstable power or signal source...aka a high resistive open, not a short or ground, maybe?

I layman's terms, a high resistive open occurs on a normal connection/splice where the wire has been corroded to the point that barely enough current can flow through it.

Best example, remember what static scratches and pops used to sound like on the old ma bell wired telephone lines!

Perfect example, sound /current would flow but with serious restriction.

Ya makes A lot of sense. Only problem is that should theoretically show up on the computer and now that they have the computer running with the correct patch we are showing good power and continuity through all the wire systems. See my last post post for more thoughts and details. I appreciate it!