Thread:

Allison 5 speed sometimes won't shift past 3rd.

Originally Posted by TPC

Anyone have an idea what is causing this?

Will shift normally to 3rd,, then stay there.
3900 RPM at 47 mph.

Intermittent problem.
Could it be the board, the solenoids, perhaps the colum shifter not cueing up correctly holding it back?

When it does it, have you tried putting it in nuetral, then back to "D"?

GT

when's the last time you put a fuel filter on it? if its been over 10k miles, change the filter and see how it does. if the filter is clogged, the trans won't shift right. try the filter and pm me, let me know how it goes.

Had the same problem with mine would go in to limp home mode 3rd gear only until I cleared the code found out the c-2 clutches where overheating. Rebuilt Trans never had a problem sense then. 2004 duramax banks twin turbo set up on it now. Still have not had any problems sense the build.

any news tpc?

Originally Posted by IMPATIENT 1

any news tpc?

Yes!
It was the 4th gear solenoid puked.
The trouble message came across as "low voltage pressure switch."

Replaced the Solenoid,, good to go.

The "service engine soon" idiot light, (not message center message),, was a separate issue.
On the early Allison W 1000's, the front transmission pump may loose it's fluid prime if sitting for a long spell. No BFD, nothing to sweat.

It easily and immediately draws fluid up when ya start it, but the idiot light goes on in the meantime from sensing low pressure for a mili second.

It's just a nuisance, and if the trans is ever apart the improved replacement pump has a fluid back flow prevention kinda dealio to prevent it,, but nothing to worry about.

8 years ago Jordy mentioned in HB the only thing that goes wrong with the Alison's is maybe a drip from a seal, a solenoid might go south, thrust washers wear out with high mileage or from towing a 27.000 GVW trailer with a 12.000 GVW rated truck,,, and some of the early ones might get some contamination on the board causing them to act wacky. Wash, rinse, blow-dry, re-install the board..

Pays to have an Alison shop look at it.
The nationwide chains just wanna sell ya a new tranny we've learned in the RV forums from the folks that got second opinions for the same issue. A new trans they were quoted about $4500, fixing the solenoid was a few bucks over $300 and that included a trans service of fluid and filters.