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MAN55LE · 08-22-2021, 02:41 PM

…looking for some help. I have a 2001 Fleetwood expedition 34N freightliner chassis with a Cummins diesel pusher motor and an Allison 2000 transmission. My wife and I are from New York and drove our motorhome out to California towing a 20 foot trailer with toys. It performed very well. We have taken care of normal maintenance. When we went back home and park the motorhome in storage for six months ….we returned and upon driving the first 5 miles the motorhome would spike to about 3000 rpm almost as if dropping in nurturant or putting the Jake brake retarder on. The Jake brake wasn’t on and I backed out of the fuel and rpm returned to normal when I reapply several seconds later the RPM would spike again almost as if downshifting might have even downshifted but I let off the throttle as to not damage anything. Thought that maybe it was a low-voltage issue replaced all batteries and connections checked fluid levels… also unplugged transmission connections and used contact cleaner and dielectric grease went for a test ride and it continues to spike RPM random downshift syndrome. Headed to utah for our wedding and was supposed to bring the motorhome looks like will be renting a car was wondering if yall had any thoughts I thought maybe a throttle position sensor could be throwing something off or may be a transmission solenoid I didn’t know if anybody knew of a common issue. feel free to call or text me if it’s easier Chris 845-406-5445 thank you so much for your help if you can please and thank you located in Lake Elsinore California currently 🙏thanks

MrMark52 · 08-23-2021, 03:30 AM

Quote:

Originally Posted by MAN55LE

…looking for some help. I have a 2001 Fleetwood expedition 34N freightliner chassis with a Cummins diesel pusher motor and an Allison 2000 transmission. My wife and I are from New York and drove our motorhome out to California towing a 20 foot trailer with toys. It performed very well. We have taken care of normal maintenance. When we went back home and park the motorhome in storage for six months ….we returned and upon driving the first 5 miles the motorhome would spike to about 3000 rpm almost as if dropping in nurturant or putting the Jake brake retarder on. The Jake brake wasn’t on and I backed out of the fuel and rpm returned to normal when I reapply several seconds later the RPM would spike again almost as if downshifting might have even downshifted but I let off the throttle as to not damage anything. Thought that maybe it was a low-voltage issue replaced all batteries and connections checked fluid levels… also unplugged transmission connections and used contact cleaner and dielectric grease went for a test ride and it continues to spike RPM random downshift syndrome. Headed to utah for our wedding and was supposed to bring the motorhome looks like will be renting a car was wondering if yall had any thoughts I thought maybe a throttle position sensor could be throwing something off or may be a transmission solenoid I didn’t know if anybody knew of a common issue. feel free to call or text me if it’s easier Chris 845-406-5445 thank you so much for your help if you can please and thank you located in Lake Elsinore California currently 🙏thanks

Check your tranny fluid level?

Was tranny fluid added recently and if so, was it the right kind?

Any signs of tranny fluid leakage on the ground under where the coach sat for 6 months?

rssnape · 08-23-2021, 08:55 PM

Quote:

Originally Posted by MrMark52

Check your tranny fluid level?

Was tranny fluid added recently and if so, was it the right kind?

Any signs of tranny fluid leakage on the ground under where the coach sat for 6 months?

I would agree sounds like low fluid level.

MAN55LE · 08-23-2021, 10:38 PM

No signs of leaking I did check the level and it was good

rssnape · 08-24-2021, 04:33 AM

Quote:

Originally Posted by MAN55LE

No signs of leaking I did check the level and it was good

You checked it with the engine running at idle?

MrMark52 · 08-24-2021, 06:52 AM

Right kind of tranny fluid?

MAN55LE · 08-24-2021, 11:07 PM

I checked The fluid while it was running at idle, and I have use the correct fluid. We parked the motorhome and it was running great… then came and got it 9 months later… now the RPM spike syndrome.

Skip426 · 08-24-2021, 11:38 PM

The Allison 2000 series , is basically a beefed up 1000 series same as GMC
3/4 and one ton trucks with Duramax or the 8.1L .

When first introduced the GMC trucks with 1000 series had issues with water intrusion into the NSBU module on the side of the transmission . ( Neutral Safety Back Up ). when the signal from the NSBU was scrambled by the moisture the transmission would default to second gear , no matter what speed the vehicle was traveling .
This sound like what's happening to your coach .
I can't remember what year of the 1000 series was involved in the replacement of the NSBU for one with better waterproofing , but 2001 could be suspect .

The NSBU location is shown in this installation manual , for the Arens SBWActuator , that I believe your coach is equipped with .
I'd be inclined to contact Allison transmission head office to see if the build date of your NSBU is suspect , or if they have reports of similar sifting issues like your having.

EDIT : On a re-read of your post , I see this started after storage for months , first thing to check would be for rodent damage to the wiring at the NSBU .