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free2wander · 02-03-2017, 07:20 PM

Earlier in the week, as we were traveling to our next park, our transmission started hanging up in 2nd gear and the "ABS light came on. I pulled over, in the middle of nowhere, then eased onto the highway and all seemed well. About 50 miles down the road the same thing happened with the same results. Then after about 200 miles and not dar from out destination, the "check transmission" light came on as well, then reset itself. When we reached our destination and began to deploy our slide, we realized our battery bank was dead. My question is, does the Allisons system depend on a fully charged battery, or is this probably something else? We are miles from dependable service centers and curious if I should hit the "panic" button at this point.

twinboat · 02-03-2017, 07:32 PM

Your alternator, when working, will keep your chassis batteries at 13.5 volts.
The electronic engine and transmission controls depend on that.

Did you notice less then 12 volts on your dash gauges ?

saddlesore · 02-03-2017, 07:37 PM

Quote:

Originally Posted by free2wander

, we realized our battery bank was dead. My question is, does the Allisons system depend on a fully charged battery, or is this probably something else? We are miles from dependable service centers and curious if I should hit the "panic" button at this point.

I would find the reason that the batteries are not getting a charge.
The tranny does need a charged battery, You most likely are just running off the alternator charge circuit on the big engine.
As a "get by" until you can get to a shop try running the gen set while going down the road, this may give you enough electrical power to keep the tranny happy..

Kiawah · 02-03-2017, 07:38 PM

Well yes, you chassis battery needs to be good and have a charge. Your transmission and engine have electronic computer controls and need power for them to start and run.

Need to determine if your alternator is good and putting out voltage, and whether that voltage is getting to the chassis batteries to charge them up.

Old Scout · 02-03-2017, 07:40 PM

Absolutely--both the Cummins engine and the Allison transition control modules require 12v power to operate properly. Not certain what the perimeters are, but both will shut down or throw codes if voltage drops low enough. On the other side of the coin is bad grounds. A poor ground will cause similar issues with both the engine and tranny....

John Jones · 02-03-2017, 07:56 PM

When my alternator failed the voltage started to drop, I noticed my gauge and tried to drive for a bit to get to a good area to pull over. As my chassis battery got down to 8/9 volts my coach started running bad, the transmission light came on and it wouldn't shift properly.

Its hard to diagnose without being there but I would check your alternator output. If in fact your alternator is not working, you can put a jumper between between your chassis and your house batteries and start your generator. Thats how I go my coach home so I could change out my alternator. You can drive it that way until you can get the alternator fixed.

vsheetz · 02-03-2017, 07:59 PM

When you say the battery bank is dead. Are you speaking to the house or chassis batteries? The transmission and engine electronics are powered via the chassis battery. If you are referencing the house batteries, suggest to check the chassis batteries as well.

free2wander · 02-03-2017, 08:02 PM

Thanx Guys! I suspect my alternator is not charging and intend to do an alternator check as soon as weather permits. Meantime, I have installed a new battery maintainer (float and a charger in the battery bay powered by the genset . . . a just in case measure). Finding a DEPENDABLE service tech is my next concern!

jimmy braden · 02-03-2017, 11:30 PM

Do you have an onboard batter monitor or at least a multimeter? Check voltage with engine off and also idle.

Hopefully your moving now?

slickest1 · 02-05-2017, 03:06 PM

I had my alternator quit while travelling down the road. I was trying to make it to the next town but the voltage dropped and the transmission light came on. The Allison then kicked into neutral and would not shift. I had to run jumper cables from the house batteries to the coach batteries to get me to town, and it ran fine like that. I am sure that that is most likely your problem as well.