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Transmission Lag Issue

Still searching but... Just took our new to us 1999 U320 out for a maiden trip.  Everything going great except about the last 10 minutes of our trip we had a weird issue with the transmission.  About 260 miles into a 280-mile trip everything was going great.  Mostly all highway driving.  When we got into town, at two traffic lights, when we went to start out it sounded like it was in Neutral and would not go.  In fact, it started coasting backward at one.  I quickly put in Neutral and then back in Drive and it went fine.  Since I was trying to get going and out of traffic I can't tell you exactly what the shifter read.  No codes showed up on Silverleaf that I can remember.  Any gut reactions as to what happened.
Luke & Sandy (still many work years to go...)
1999 U320 36 Build #5387
2013 Jeep Wrangler Unlimited
Previous 1997 Winnebago Vectra Grand Tour 35WQ major interior remodel
Previous several SOB trailers, Class C, fifth wheels.

Re: Transmission Lag Issue

Reply #1 –
The first thing to do would be check trans oil level using the shift pad
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Transmission Lag Issue

Reply #2 –
Read the DIAGNOSTIC CODES from the Allison shift pad.

Ignition on, engine off:

Press up and down arrows at the same time.

Press them again.

That will bring up d-1 and any stored codes.

If there is a d-1, press "mode" to bring up d-2.

Repeat until you get a d- "some number" and - -.

Look up the codes in your Allison owners manual or on Allison's website.

Let us know what you find.
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: Transmission Lag Issue

Reply #3 –
D1 35 00
D2 - -
Luke & Sandy (still many work years to go...)
1999 U320 36 Build #5387
2013 Jeep Wrangler Unlimited
Previous 1997 Winnebago Vectra Grand Tour 35WQ major interior remodel
Previous several SOB trailers, Class C, fifth wheels.

Re: Transmission Lag Issue

Reply #4 –
Allison transmission codes:
Forest & Cindy Olivier
1987 log cabin
2011 Roadtrek C210P
no longer 1999 36' U320 build #5522
2013 Rzr 570 & 2018 Ranger XP1000
2006 Lexus GX470
2011 Tahoe LT 4x4
Previous 1998 45' 2 slide Newell, 1993 39' Newell

Re: Transmission Lag Issue

Reply #5 –
35 00 POWER INTERRUPTION

Check all electrical connectors to ECU and on transmission
Dan - Full timing since 2009
2003 U320 40' Tag 2 slide

Re: Transmission Lag Issue

Reply #6 –
Could bad coach batteries or ones that are in their death throes cause the issue?
Luke & Sandy (still many work years to go...)
1999 U320 36 Build #5387
2013 Jeep Wrangler Unlimited
Previous 1997 Winnebago Vectra Grand Tour 35WQ major interior remodel
Previous several SOB trailers, Class C, fifth wheels.

Re: Transmission Lag Issue

Reply #7 –
Quote from: coastalbuilder –
Could bad coach batteries or ones that are in their death throes cause the issue?
In my opinion, low voltage could cause issues.

 If the voltage on the coach batteries is ok (and relatively stable) with engine batteries being charged by the alternator while the engine is running, then less likely so.

At idle at a stop light the alternator is putting out lower voltage/amps.  Check the voltage at start batterie with engine off, and again at engine idle.

Dan - Full timing since 2009
2003 U320 40' Tag 2 slide

Re: Transmission Lag Issue

Reply #8 –
I would check voltage when this occurs AT THE BREAKER panel in front of the passenger's seat.  Identify the two feeds to the Allison ECU and check both for proper (i.e. over 12 VDC) voltage.
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: Transmission Lag Issue

Reply #9 –
Will do.  I know the batteries are going.  I have to use Boost to start and Silverleaf was showing dropping below 12 on the trip.  It would fluctuate between say 11.7 and 12.2 on the trip.  Before the trip, when Roger and I were running through the Silverleaf screen, I believe it got down to 10.6 with engine off, ignition on.
Luke & Sandy (still many work years to go...)
1999 U320 36 Build #5387
2013 Jeep Wrangler Unlimited
Previous 1997 Winnebago Vectra Grand Tour 35WQ major interior remodel
Previous several SOB trailers, Class C, fifth wheels.

Re: Transmission Lag Issue

Reply #10 –
Low and/or erratic voltage can damage electronics.

Fully charge the batteries and have them load tested.

BUT, unless totally shot, the alternator should have been able to maintain them at 13+VDC while driving.  So, you may have more than one problem.  But start by verifying that you have good batteries and that the connections are clean and tight AND that the cables themselves are still in good condition (ends clean shiny copper, not green copper oxide).
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: Transmission Lag Issue

Reply #11 –
I had a similar transmission event. I thought it was weak batteries due to the power interuption code. When I removed the batteries I found light corrosion. I cleaned all the battery connecitons and found the ground to the engine block wasn't tight. Starting problems dissapeared and and no additional transmission events. Glad I checked everything before buying 3 new start batteries.
David Bethard
2003 U320 - 40ft. Build #6159
ISM 500hp
2006 Jeep Liberty CRD
2021 Honda Goldwing DCT
 

Re: Transmission Lag Issue

Reply #12 –
Coastal,  In case you don't know where the Transmission ECU is located, mine is behind a carpet covered panel at the drivers left foot,  The panel is held in place with screws buried in the carpet.  There are 2 large wire bundle connectors on the ECU.  Our coaches are different years, but suspect it is similar on your coach.  Sometimes unplugging and replugging helps.
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt