2001 Beaver Marquis. Transmission selector not working

[Vernon Boen]

I have a 2001 Beaver Marquis that wont start. I've been trouble shooting for some time with no luck. I have discovered that it will start from the mechanic button on the rear. I noticed the transmission selector pad is not displaying anything. I have replaced the solenoid and the key switch. I have chased all the wiring down and cleaned all connections and checked all the fuses. I have noticed when I turn the key on and off that each time I turn it back on the economy button on the pad will briefly flash. I also noticed when I start it from the rear that it does display a check transmission light and exhaust brake light on. I have the jake brake off but light still says on. I thought I'd post here for some possible insight. I am probably gonna have a mobile service technician come out and hook up computer in hopes of some direction since there's a check transmission light on that may point me in the right direction. Asking here first in case there is something simple I'm overlooking.or a fellow member who's previously had this issue. When I  parked it last  there was zero issues and I've never experienced any trouble with the transmission pad. Thanks in advance for any assistance

[David T. Richelderfer]

Your description of the symptoms is a bit different than my one-time experience but Kenny Carpenter (now deceased, Bend Beaver expert) guided me to look under the transmission keypad into a black clamshell box for a couple of fuses, one of which had blown.  He told me that to start the engine, the transmission must report neutral (N) on the keypad.  The clamshell box is accessed by removing the large side panel under the console just left of the pilot's left leg.

[Vernon Boen]

Thank you for the reply. I have already located this box and checked both fuses. They weren't blown but I changed them anyway with no luck.

[Eric Maclean Co-Admin]

Vernon
In the coach assist library there is the Allison automatic troubleshooting manual which includes logic and wiring diagrams which can help you understand and diagnose your issues.

I know you probably already have but I'll suggest it anyway.
In the battery bay there should be two or three 10 amp ATO fuses ( the red ones ) one is for the engine ECM (engine control module) power the other is for the TCM ( transmission control module).
Its not uncommon to find the transmission control module fuse blown which will cause the transmission control module to not function and result in no readings on the shift pad.

Next there are fuses in the transmission relay box the black box with the screw on cover mounted in the electrical Bay one of those fuses may be blown as well.

Again the transmission troubleshooting manual will be of great assistance in any of this.

Hope this helps
Eric

[John Bagwell]

I had the same problem with my 2001 Monterey.   We figured the keypad was the issue.  I send it to Transmission Instruments, and they tested and rebuilt the unit, and it now works great.  It was tested and rebuilt for $348, and comes with a 2 year warranty.  I also send them the ECU unit so the could test it.   My keypad just lite up with the “mode light” on, engine would not start or turn over. 

[Vernon Boen]

I have searched all over the battery bay for the fuses but I still haven't located them. Any suggestions where I might find them?

[Eric Maclean Co-Admin]

The fuses are usually in in line fuse holders attached to the bundle of battery cables headed out the rear of the battery compartment.

Eric

[Vernon Boen]

Still needing some help....,I replaced the 2 chassis batteries. One of them tested weak and they were 7 years old so I figured just replace and save some hassle later. I also know Allison transmission are very dependent on constant voltage so I wanted to eliminate voltage issues. As I stated before the coach will start at the rear start button in engine bay and I happened to notice the brake lights were on when I turn the key switch on. The lights I have on the dash are check transmission and engine brake applied. I'm assuming something between the two are responsible for the transmission pad not lighting up. I checked the jake brake switch and it is in the off position. I also turned the jake brake on and accelerated the engine and the jake brake engaged when I release throttle. So I know the jake brake switch it ok and the jake brake is performing properly. It also has a different light on the dash that comes on when jake brake is turned an goes out when its turned off aside from the one that is staying on all the time with check transmission light. Ive also checked the brake light switch and it is good. I have also checked all relays and replaced every fuse. Any ideas?

[Vernon Boen]

Hello Everyone. Just wanted to let you all know I got the problem resolved. I have lost power 12 volt battery voltage to the vim somewhere between the vim and battery. I looked every where I could think of for the issue and finally just chose to run a new wire from the constant 12 volt side of the solenoid in the electrical bay and that totally fixed my issue. Thanks for any input given and hopefully this helps someone else in the future.

[David T. Richelderfer]

I didn't know what a VIM is or does.  So I asked GOOGLE AI for information.  The following is the reply... relative to a vehicle.


"Vehicle Interface Module (Chassis & Transmission)

"On heavy-duty diesel pushers and class A motorhomes (especially older models equipped with Allison transmissions like the WTEC systems), the Vehicle Interface Module (VIM) is a critical black control box.

"What it does: It acts as an electronic translator between the engine, the chassis, and the Transmission Control Module (TCM). It houses essential relays and dedicated fuses that feed power directly to the transmission’s electronic brain (ECU/TCM).

"Why it matters to owners: If your motorhome suddenly fails to crank or won't start after replacing the house or chassis batteries, a blown fuse inside the VIM box is an incredibly common culprit.

"Where to find it: It is usually tucked away in the front electrical bay (directly under the driver's window), behind the brake pedal firewall, or inside the dash area near the shift keypad panel."


Hmmmm... is that the black clamshell-like box directly under my transmission control pad, left side of the pilot's seat in the console.  I know that box has two fuses inside it.

[Vernon Boen]

Yep that's it.