[Stinker]

I just picked up a 1999 Gulfstream Tourmaster diesel pusher. It has a Cummins with the 6 speed Allison. The issue is, about half the time the engine is started, the shift indicator displays "*" and it will not shift into any gear. I can shut it off and restart it with the auxiliary start button pressed and it displays "N" and operates normally.
I thought maybe low voltage could be affecting the trans computer. All batteries are new, (house and engine), and the 4 engine batteries tested at over 1000 amps each.
I'm new to the motor home stuff and am just starting to research this, but thought I could get some insight here. Thanks in advance!

 

[BlackBeard]

Does it ever give you fits when starting, like it won't crank thinking it's not in park or neutral?

 

[Stinker]

No, it starts ok. I found the negative battery cable loose at the battery this morning and repaired that. I thought I had it whipped, but not yet.

 

[skwerl]

Is it the Allison MD3060? I have that trans in my bucket truck and it is highly sensitive to voltage irregularities. Over the last 7 years I've had multiple issues with the crappy GM battery cables, swapping out ends and finally replacing the entire cables. Had a loose terminal post in one battery that took me a while to find. Also there are a couple speed sensor connectors on the bottom/back of the trans and the wiring to those had become brittle and all the insulation fell off. The last time I had issues I had to replace that burnt wiring and it's worked perfect ever since.

I highly recommend using the good synthetic trans fluid. Mine takes about 7-8 gallons and I paid about $95 per 5 gallon bucket. In 7 years I've changed it 3 times which sounds like a lot but a rebuild can run $8-10K.

 

[pist0lpete]

I would say check your connections on both the power and ground. I would also check to see if you have any codes. You can check error codes on the shiftpad see pg. 50 http://www.beaveramb.org/PDF/PDF Manuals/allisoninformation/Allison Transmission.pdf . If your power and ground wiring checks out I would say the next most likely thing is the J1939 Can Bus wiring.

 

[1969x11]

Some allisons have a electronic controller / for the shift linkage designed alot like an old slot car controller on them. These things are under the vehicle and in a real bad spot for corrosion. Up here in the great white north its a common issue from road salt and age for them to go bad. Exactly the same symptoms as yours. Id have a look there.

 

[Pro Thunder Cycle]

They are called cat eyes and typically when it happens the ECU is taking a dump. Verify all connections at the ecu especially look for green corrosion.

 

[spidergearsman]

Park neutral switch full of water

 

[Stinker]

Thanks for the help. I'll see what I can find. Sure hope it's not the ECM. Any clue what they cost?