Allison tranny "lock out ciruit"

Not sure if that is the correct definition of my problem.
After 3 months of interior remodeling it was time to fire everything up, fuel and get ready for a short hop.

I was having problems with starting so first thing was clean all the battery terminals and make sure that all batteries are topped off. Since there had a bit couple of cold nights I turned the block heater on and flash bang. Appears there was a short. Reset breaker which had tripped. checked wiring and all seemed ok, hit switch again and same thing. So I unplugged it so that would not happen again.

When about doing the pre-check and fired the MH up no issue. I was going around checking everything as I was still planning on fueling. When I got back in the cockpit there was a check transmission dummy light and no indicator lights on the shifter console. I shut the engine down and them I was unable to start the engine, check trans light still on and no indicator lights on the shifter. After some research I found out about a fused compartment that would cause this exact problem. Now the issue, where is this panel / compartment is located. I have the generic transmission schemetic but does not show location only that there are two fuses related to transmission & ignition operation.

Does anyone have any insight into this issue, any help would be greatly appreciated.
2001 Winnebago Itasca Horizon 36cd
330 HP caterpillar 3126
6 speed Allision 3000Mh

edit by staff - changed message icon to topic solved, this thread will stay in the Winnebago board since there is information about where the transmission control module is located on the chassis

I am not certain, but I believe it might be in the same compartment that has the fuses for the trailer hitch lights.  I remember reading threads where someone is looking for trailer (towed) fuses they mentioned something about also having some transmission stuff there.  Could be what you are looking for...

In any case, IF this is correct, you are looking around the driver side rear of the coach.  In some models (like mine) its behind a panel in last bay at the very back of the coach to the right of the radiator.  In others, it was behind a panel in the electrical bay.  In both cases you are looking for a vertical plate that is held on by screws.  Removing the screws and the plate gives access to the fuses.

Thanks I'll start looking around there. Thanks for the info...

Most Freightliner chassis have the transmission controller and relays in a rear compartment, typically on the passenger side There is no requirement it be there, but it's the convenient location for them with the wiring harness that comes with the chassis.  It's possible there is a problem with the wiring harness that runs forward to the shifter panel, but more often its a loose wire connection or similar problem in the back.

If the transmission can't report that it is safely in neutral, the starter interlock prevents the engine from starting.  Therefore most any problem that shuts down the shifter panel or stops communication will result in a starter lock-out.

Gary RV_Wizard said:

Most Freightliner chassis have the transmission controller and relays in a rear compartment, typically on the passenger side There is no requirement it be there, but it's the convenient location for them with the wiring harness that comes with the chassis.  It's possible there is a problem with the wiring harness that runs forward to the shifter panel, but more often its a loose wire connection or similar problem in the back.

If the transmission can't report that it is safely in neutral, the starter interlock prevents the engine from starting.  Therefore most any problem that shuts down the shifter panel or stops communication will result in a starter lock-out.

Click to expand...

I have a basement heat pump. Do you think with this setup they may have the transmission controller some where else? We have had no lock finding it on the passenger side.

No, look on the driver side.  Winnebago usually puts it on that side due to the basement air on the passenger side.

First try looking in the very back.  Remove the screws along the bottom of the vented panel, raise it (not supported, you'll have to brace it) and see if there is a panel to the right (very back) of the radiator.  There are usually 3 fuse blocks, one for the towed lights, one for the tranny, and a third.

If not there, then it's probably slightly forward, behind a panel in your electrical bay.  Check out this thread... while it is more about the towed fuses it has some photos that might show you what to look for.

http://www.irv2.com/forums/f101/separate-fuse-box-location-for-trailer-hitch-wiring-does-it-exist-179120.html

emiddleb said:

No, look on the driver side.  Winnebago usually puts it on that side due to the basement air on the passenger side.

Click to expand...

Yup, driver's side under the rearmost bay panel.

John Canfield said:

Yup, driver's side under the rearmost bay panel.

Click to expand...

Checked and it is not there. There is no panel beside the A/C and no panel in the electrical compartment.
Getting frustrated as we have searched for two days and still can't find the module. Any other suggestions?

adun015
Look inside the Allison VIM (vehicle interface module)...it has fuses and relays inside.
http://www.nwrvsupply.com/mm5/graphics/00000001/AllisonTrans%20VIM.jpg

On my Safari the VIM is up/under the dash near the center of the front firewall...(but it could be most anywhere on/in your coach).

Not sure how well this would work but you could attempt to crawl underneath and find the tranny wiring harness and attempt to run it down. Or call Freightliner, they might be able to assist.

John Canfield said:

Not sure how well this would work but you could attempt to crawl underneath and find the tranny wiring harness and attempt to run it down. Or call Freightliner, they might be able to assist.

Click to expand...

I have already tried tracing and no luck. I have also talked with Freightliner, all they were able to do is confirm that it is somewhere but no clue as to where. Main thing they were able to do was tell me that this could cause the issue I have.

mel s said:

adun015
Look inside the Allison VIM (vehicle interface module)...it has fuses and relays inside.
http://www.nwrvsupply.com/mm5/graphics/00000001/AllisonTrans%20VIM.jpg

On my Safari the VIM is up/under the dash near the center of the front firewall...(but it could be most anywhere on/in your coach).

Click to expand...

I have removed most of the dash and still no module. You are correct it could be anywhere and there is a lot of anywhere under a motorhome. :-\

Did you try asking Winnebago Owner Relations? That's a long shot but worth a phone call. I'm really surprised Freightliner didn't know where they put the module. I wonder if Allison has a group that specializes in motorhomes you could call.

Actually John, I'm thinking your idea of calling Winnebago is the right answer.  If it's mounted somewhere up in the coach (compartments etc) and not on the chassis frame itself, Freightliner would have no idea where the RV manufacturer put the module. 

Now if its mounted on one of the firewalls like under the bed or up front, then probably Freightliner did it.  But anything beyond the bare chassis would be the RV manufacturer's decision as far as installing it.

I'm really surprised Freightliner didn't know where they put the module.

Click to expand...

Freightliner ships the chassis with the modules dangling on a loose wire harness, not permanently mounted anywhere.  The RV body builder mounts them wherever they like.

John Canfield said:

Did you try asking Winnebago Owner Relations? That's a long shot but worth a phone call. I'm really surprised Freightliner didn't know where they put the module. I wonder if Allison has a group that specializes in motorhomes you could call.

Click to expand...

I have contacted via e-mail and their response was to contact Freightliner. I just feel like I'm going around in circles.
Will keep searching.

Well, I'm stumped.  The two most common places are as described... very back of the coach to the right of the radiator in the small cutout, or behind a panel in the electrical bay, usually upper right close to the door, held on with several screws.

Since most of the info I've seen in other posts says the tranny relays are near the towed/trailer hitch light fuses/relays, something you might try is turning on your turn signal (in accessory mode) and then go to the back of the coach and see if you can hear the turn signal relay clicking.  Might narrow down the area for you.

Mine is in the electrical bay where the aux start solenoid sits. Maybe have someone hit the aux start and walk around the coach , that is how I found mine it's in the compartment where all the relays are covered with a black plastic cover.

Thanks to all for your input. The ECU has been located. It was under the bed on the back of a the metal separator.  It was not visible but we finally traced it down ( thanks John ) . All checks on the plugs show they are good, a look inside the module showed that there are a few burned resistors and a lot of heat to the intel chip.
Starting to look for a replacement part. Does anyone know best place to purchase. I have found used on line but need to find out if I go that route will the replacement need programming. Again thanks to all for your input.

Most excellent Alan, your perseverance finally paid off!  ) There used to be a guy on the forum that was an Allison tech (allisonman?), maybe he's still around and you can contact him. Second choice is find an Allison service center and ask them about flashing a new or used ECU.

What's the part number on the Intel chip?  I have the capability to work on through the hole or surface mount boards and could take a look assuming the board isn't potted and a potential replacement chip could be found (assuming that's the problem.) Some chips are custom made and/or stenciled with the customer's part number.  There's probably a custom micro controller or FPGA on the board and of course memory.