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Topic: Flickering display on Allison shift pad  (Read 890 times) previous topic - next topic

Flickering display on Allison shift pad

Today on our trip to Nac from McKinney I noticed that the displayed gear (6) and the mode light were flickering on and off.  Any advice as to what may be wrong and how to fix it?

Thanks in advance.

Re: Flickering display on Allison shift pad

Reply #1 –
George,

First, use the shift pad to check for codes:

Ignition on, engine off:
Push up and down arrows at the same time.
Do it again.
That will bring up d-1.

If there is a diagnostic code it will give you a two digit code.

If no codes, it will display d-1. then - -.

Two weeks ago there were no Allison stored codes-- I checked.

NEXT: is to check voltage to the Allison ECU.  Two hots. 

IF they are OK, next stop in the DFW area is: Transmission Instruments

This is exactly what John has done for a living for a long time-- troubleshooting and fixing Allison shift pads and ECU's.

Re: Flickering display on Allison shift pad

Reply #2 –
Can someone help me with the following (year 2000 U295 3600):

1.  How do I remove the Allison shift pad so I can examine the connections from the ECU?  See the attached pic. There are six small screws on the top of the panel containing the shift pad.  Remove them and lift?

2.  Where is the ECU located?  I thought it was in the Joey bed bay, but the two boxes there are for HWH and the ABS system.

Thanks in advance.

Re: Flickering display on Allison shift pad

Reply #3 –
George,
1. Basically yes with those 6 screws out the hole panel will lift out. If you have to remove the push pad you will see the bracket that holds it on once you get it up and can expose the back side.

2. The ECM you are looking for should be behind the carpeted kick panel just below and toward the front of the coachwhere you are pulling the shift pad. It is a pain to slip that carpeted panel out but once you get it out the ECM is mounted on the wall.

Check your PMs

Pamela & Mike

Re: Flickering display on Allison shift pad

Reply #4 –
That is of course the right info from  Pam and Mike as usual.
We have the same model and I have had that panel off to fix indicator lights in switches.
JohnH

Re: Flickering display on Allison shift pad

Reply #5 –
Thanks to those that tried to help me find the ECU for the Allison shift pad.  I still have not found it, but I have an appointment at MOT tomorrow and Keith should know.  The hope is that the flickering is a loose cable connection between the shift pad and the ECU.  I have started the coach a couple of times over the weekend and the display has been bright and steady.  No flickering.  Seems to be an intermittent problem.  I should add that there were no Allison diagnostic codes displayed. 

Re: Flickering display on Allison shift pad

Reply #6 –
My trans ECU is in the water pump bay near the ceiling.

Re: Flickering display on Allison shift pad

Reply #7 –
Just an observation.  My display also was flickering the other day while driving with the lights on...turned out the dimmer rheostat was in a mid position and once I went full bright on the rheostat, or turned off the lights, the flicker stopped.  FWIW.  Woody.

Quote from: George Hatfield –
Today on our trip to Nac from McKinney I noticed that the displayed gear (6) and the mode light were flickering on and off.  Any advice as to what may be wrong and how to fix it?

Thanks in advance.

Re: Flickering display on Allison shift pad

Reply #8 –
Location of ECU... Joey Bed bay, aft wall, driver's side.  See attached.  I must have been affected by temporary blindness not to have seen it!

George

Re: Flickering display on Allison shift pad

Reply #9 –
George,
Thanks for the info this will sure help out  others.

I wonder when or why they moved it's hiding place around with either different years or  coach trims. This is a lot easier to get to than where others are located.

Mike
 

Re: Flickering display on Allison shift pad

Reply #10 –
In addition to Keith finding the ECU for the Allison on Monday, one of the MOT techs (Clyde) checked the connections between the ECU and shift pad.  All seemed to be OK.  He also discovered a blown 10amp fuse near the rear of the engine.  See the attached pic.  I think he thought these were part of the Allison system.  Not sure.  Anyway, one fuse (10amp) of the three was blown.  And if a new fuse was inserted, it immediately blew.  He soon found that the fuse was defined on wiring diagram A-7211.  It went to a relay labeled VP44 and a fuel pump VP44 (see attached).  This obviously raised the question, did I have a fuel pump problem?  The engine was running fine and I could find no error codes with Silverleaf. 

I talked to Keith Risch and Aubrey Lee at MOT.  They didn't know the purpose of that circuit.  Aubrey even made the drawing it is shown on, of course, years ago (1999) when he worked for Foretravel.  What a nice guy!  I also talked to Alton at FOT and he didn't know what it was for. The only person that seemed to know was Bernd.  I left a message for him to call me which he did while we were on the road.  Bernd said the blown fuse went to an "auxiliary fuel pump" (my wording) of some sort, but that the pump had been removed from most coaches since it did not work very well.  So the blown fuse was nothing to worry about.  It appears to have been much ado about nothing. 

By the way, the flickering has not returned.  We drove 150 miles west from Nac to Caldwell, TX today.  Some construction along the way, but overall an easy trip.