Skip to main content
Topic: Allison 3500 fault (Read 2439 times) previous topic - next topic

Allison 3500 fault

I've encountered a shifting problem the last couple days.  It's always at low speed in first gear making a sharp turn.  There's a hard shift and the Allison ends up in neutral with the selected gear window flashing.  I was finally in a position these evening when I could check for fault codes and got 3500 at D1, which the manual says is Power Interruption.  I unplugged and replugged the three electric cables at the Allison CPU.  Is there anything else I should do before I hit the road in the morning?
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Allison 3500 fault

Reply #1
Brett,

Did the shift panel go to "snake eyes"?

There are two power leads to the Allison ECU.  The "memory" power which goes through a 5 amp fuse. 

The other one, and the power lead that is suspect is the one supplied by the ignition solenoid since it is only hot when the ignition is on.  Any other "ignition hot" issues-- dash HVAC fan continue to work as it should?

The other Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Allison 3500 fault

Reply #2
Brett,

I hadn't noticed any other actions when the tranny died before, but today I did.  Everything was fine all day until I turned into our site for the night.  I remember what looked like a snowflake where the shift number should be.  All the dash gauges flashed and the HVAC quit momentarily.  Would the ignition solenoid behave this way?

The other Brett

Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Allison 3500 fault

Reply #3
When I had similar problems with my transmission it turned out the altenator was shot.

Start the generator to see if the problem goes away.

best, paul
1999 U320 40' 1200 watts on roof. 12cf AC/DC Cold plate fridge/freezer. VMS 240 CL Honda Element

"When you arise in the morning, think of
what a precious privilege it is to be alive...
to breathe, to think, to enjoy, to love."

~ Marcus Aurelius

Re: Allison 3500 fault

Reply #4
Brett,

In a word, YES.

But, easy to diagnose. 

With ignition off, identify the large lug on the ignition solenoid that does not have power.  Hook up a voltmeter to it. 

If symptoms appear, check voltage.  If no voltage, one of two issues-- either the ignition solenoid is failing, or the ignition switch/wiring from ignition switch is dropping. 

If voltage at the "out" lug drops causing this, next step is to see if the signal terminal is loosing 12 VDC or if the solenoid is failing.

So, hook up the voltmeter to the signal terminal.  If you have two voltmeters, or a voltmeter and test light, you can monitor both at the same time.

Now, if this happens and you need to keep moving, the "work around" is to LABEL all the wires on one of the large lugs and move them to the other large lug.  In essence, you have done what the ignition solenoid does-- transmit power from one large lug to the other.

Other option is to just replace the ignition solenoid with an upgraded version. Here is the one I use:

Blue sea 9012 250-amp ignition solenoid.

L Solenoid - 12/24V DC 250A - Blue Sea Systems

Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Allison 3500 fault

Reply #5
That surprises me.  I've never had a solenoid fail intermittently this way.  There is no way I can check voltages as you suggest unless I permanently install two volt meters.  The hiccups have never lasted more than two seconds, always at the end of a day's drive, in first gear, making a tight turn.  I'll go ahead and replace the ignition solenoid anyway.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Allison 3500 fault

Reply #6
Last night the Cummins ECM threw a Speed Sensor Fault.  Could this be connected to the Allison problem?  Should I head for Cummins, Allison, or FT? 
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Allison 3500 fault

Reply #7
Brett, I had a speed sensor fault. It it gets bad enough the Allison will stop shifting. Mine was caused by a rear main seal leaking a little and it fell on the sensor. The sensor is easy to change out but the why is the hard part. I took my coach to Allison they changed the sensor and the seal.  I could have changed the sensor but not the seal so it was good I went.
2015 Born Free Royal Splendor on Ford 550 nonslide version
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Allison 3500 fault

Reply #8
The coach stopped shifting when I was halfway into my site at Rainbow's End.  At least my power cord reached the pedestal.  Anne heard sparking around the tag axle.  It's dark and pouring rain now.  Tomorrow I'll crawl underneath.  From your description, John, the speed sensor must be on the bell housing, right?
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Allison 3500 fault

Reply #9
Brett,

There are actually two speed sensors-- both external to the transmission and easy to access/replace/ etc.

But, before doing that, check that the connections from then are clean and tight-- they live in a dirty, wet environment.

Take some electrical cleaner under with you.

But, I would look for another source for the sparking.  I can't access any documentation right now, but the speed sensors are NOT high amp sources for sparking.

The other Brett
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Allison 3500 fault

Reply #10
Given intermittant ECM/TCM problems and sparking noise, I would be looking for a power connection problem.  Bad/loose ground strap from engine / trans block to chassis, connections that get stretched/moved when the rear axle/tag shifts, etc.  Allison TCMs are known to be sensitive to low voltage. 
Dave and Nancy
1999/2013 U270 36' Xtreme
Motorcade # 16774
2013 Subaru Outback
KD0NIM

Re: Allison 3500 fault

Reply #11
The "bad connection" suggestions sound plausible based on our experience. The Allison 3060 on our SOB went to "limp mode" with a speed sensor fault while we were driving on icy roads in blizzard conditions (dangerous operation as a result of some poor choices). Ice had built up on the cable and pulled it from the socket. Solution: thaw/dry cables with a hair dryer and plug it back in.
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: Allison 3500 fault

Reply #12
It was all my fault.  I had added a second positive battery cable this summer to try to improve starting performance.  I used flexible welding cable, and didn't tie it down enough.  In the heat of this fall's driving, on section sagged enough to make contact with  a pot on the driver's side tag brake and eventually wore through the insulation.  Every time I made a sharp low speed turn the coach tilt would cause a momentary short to ground, dropping battery voltage and causing the Allison fault.  I'm just sorry I have to admit my own stupidity.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Allison 3500 fault

Reply #13
:facepalm: D'oh! :facepalm: Thanks for confirming your humanity. We refer to those events as "self inflicted wounds." Fortunately, it was an inconvenience rather than a show stopper. Nice detective work! ^.^d
J D Stevens
1997 U295 CAI 36' Build #5085
2002 Subaru Outback
Motorcade 16869
Bellville, TX

Re: Allison 3500 fault

Reply #14
Brett we all make mistakes but at least this one got some brains going and we all shared in the "learning curve" of what may cause something like this to happen. So, it actually was a good thing in my opinion, now I know what may cause this to happen (should it ever do so )
John H
Coachless, now use aircraft.
1994 Ford E350 ClassC,total renovation inside and out. Now sold.
2000 U295  36' Cummins 350 c/w Banks Stinger, Resonator upgrade,Solar, LED lites.Residential fridge with slide out pantry. Build 5674. Sold
ex 92 GV 022C ored Cummins. Sold
ex 95 GV240 cat 3116. Sold
2017 Mini cooper s & 2016 land Rover LR2 HSE  LUX.
jhaygarth@aol.com    SKP #130098
treat everyone as you would like to be.

Re: Allison 3500 fault

Reply #15
Brett, Welcome to the club.  I have been fortunate that my mistakes at least have not killed me or anyone else. :)  And..... All of us here now know that a LIBERAL application of wire ties can save a lot of trouble.
Glad you found it.
Gary B

Re: Allison 3500 fault

Reply #16
I'm having similar problems. Intermittently, as I'm slowing, the transmission will slam into 1st gear. Other times, I'll get the flashing gear indicator and the transmission shifts into neutral (once when turning right on a freeway onramp). When this happens, I cannot put the transmission into gear unless I push the up and down arrows simultaneously, then select D.

My error codes are:
d1 - 2214
d2 - 6933
d3 - 3500

I was ready to package up the ECU and shifter and send them to Transmission Instruments, but perhaps it could be a power/wiring issue. I am just handy enough to screw everything up if I attempt a repair. Should I take it to Stewart and Stevenson (60 miles away), or leave it in the driveway and send the ECU in for repair?

Re: Allison 3500 fault

Reply #17
moodmeister,

Please tell us what coach or what transmission you have!!!

Certainly you will want to verify both 12 VDC feeds to the Allison ECU as well as ground are good and 12+ VDC when this occurs before proceeding.

When we know what coach you have we can tell you where the fuses/breakers are.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Allison 3500 fault

Reply #18
My error codes are:
d1 - 2214 (engine speed sensor)
d2 - 6933 (central operating processor timeout)
d3 - 3500 (power interruption)

Allison Transmission Codes Manual

Well, the good news: you are not seeing the 69-32 KISS OF DEATH fault code!

Your stored codes certainly seem to be, at least, power related.

Since failure is intermittent, that might also suggested a possible wiring or connector problem.

Try, to the best of your ability, the trouble shooting steps (link below).  If no luck there, give John Kopalek a call and pick his brain.

Troubleshooting
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"It goes without saying..."

Re: Allison 3500 fault

Reply #19
Oops! Yes...of course, I did not post the pertinent information  :facepalm:

Coach: 2002 U 295, build number 5973
Engine: Cummins ISL-400 (rebuilt at great expense)
Transmission: Allison 3000 MH 6 speed with retarder and WTEC-III Controls SN 6510310525

Where are the associated fuses and breakers?

Randy

Re: Allison 3500 fault

Reply #20
Problem Solved.

I went to a local shop and the wires to the Allison ECU were corroded. Once cleaned, everything was good, for about 100 miles or so. The slamming shifting problem resumed.

I took the coach to Foretravel for its usual pilgrimage for yearly maintenance and they did their own troubleshooting. They diagnosed a faulty speed sensor. Since replacing this part, it's shifting perfectly again.

Randy