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Jchemie · 09-12-2021, 04:17 PM

Just went thru the same thing with my ISB 300 Cummins & AllisonMC2000. Altenator wasn’t putting out the full 14.7 volts, only 12 volt and soon zippo. Alt light on dash didn’t come on because the exciter wire came off the alt, this wire was on for a while when I first started my trip then came loose somewhere down the road. Used up all the juice in the starter batteries, then found out my solenoid which connects the two battery sets was working but the internal contacts weren’t functioning. So the alt crashed right after the wire went south. Dim lights, trans stuck in gear, couldn’t re-start engine or generator. Check output of your altenator, condition of engine starter batteries too.

Johnontheroad · 09-12-2021, 04:36 PM

Had pretty well the same thing except I was stuck in 5th gear. Shut the coach down, let it cool, and all was well.... for a while. No telling when it would act up. This was my first day driving my new-to-me coach

Took the coach to an Allison service facility and they confirmed that the transmission threw an error code which had to do with either solenoid or wiring harness issues. It took two visits, but eventually Allison replaced all the solenoids and wiring harnesses and all has been well for the last 30,000 miles.

But I was still under the 5 year Allison warranty so it didn't cost me anything except a ton of aggravation.

gcederholm · 09-12-2021, 06:48 PM

OP needs to check the voltage at the chassis batteries with the generator OFF and disconnected from shore power. The Big Boy, if working correctly, will link the house and chassis if plugged in or running the generator, so is likely masking any alternator-related issues.

I’ve had a comparable issue on our 2005 Exec (similar to 2006 Sig) twice, about 8 years apart. The dash air compressor seized up and shredded the serpentine belt, which eliminated the alternator drive. I caught it quick enough while driving and started the generator from the dash. Once the Big Boy activated, there was plenty of voltage in the chassis bank to keep running.

peskyfeller · 09-12-2021, 06:53 PM

Quote:

Originally Posted by Just For Fun

Here's an odd ball one for you:
I have a 2006 Sig with an ISX600 Allison 4,000 trans

First: Driving last night, the transmission stuck in 4th gear. It would NOT automatically or manually shift up or down from 4th gear to any other gear. Fortunately the engine is strong enough to move us up and down hills, towing a full size pickup. Not the best situation/strain on this engine. But... We were unable to pull off the road since we were on winding mountain roads, at night and will no lights from highway type lighting. Think dark-twisting-mountain roads!!!!

Secondly: As we're driving, the headlights started going dim. Finally the dashboard lights went out as well as the headlights. The engine was still running well (but in 4th gear) but a red dashboard light came on "CHECK TRANS." Again, we were unable to pull off the road due to being on winding mountain roads with ever diming head lights. But I kept a vigil on the "Trans Temperature Gage" that showed relatively cool. ALL GUAGES WERE SHOWING NOTHING ABNORMAL IN TEMPERATURES! No increase in running temperature. I attempted to get a number of the actual Trans Temperature, but again, running with minimal road lights in the mountains on twisting roads is a bit tricky in itself.

Once we got to a safe place to pull over, I was really concerned about shutting down the engine with a fear of it not restarting - still being stuck in 4th gear rather than Nutral. But, due to the "smarts" wiring in this otherwise excellent coach, the front door would NOT unlock while the engine is running!!!!! So, I shut it down. This morning I turned on the engine; it started up in Nutral and started find, no resistance and moved into 1st gear when requested.

One other item: As we were driving and had NO headlights, I noticed that the "VOLT" meter on the dash was registering Zero (using a flashlight)!!! When I depressed the "Battery Boost" switch, the dash and headlights came on strong for about 30 seconds. But when I released the Battery Boost switch, within 30 seconds the lights turned off and the VOLT guage went to Zero. It also registers "12" this morning when I started the engine - but I also have the generator running. Not sure if that makes a difference. I also check the batteries last night and they registered about 12.9. Generator running now to bust them back up.

I checked the "engine" oil this morning; full. I can't find where the Trans oil dip-stick is. Anyone know?

Anyone had a problem like this? All educated ideas/suggestions wanted?

Thanks.

Your problem is the alternator has gone bad. I had a similar experience and when I saw the voltage had dropped I started my generator. Suddenly everything ran fine. Never forget that the generator will supply 12 to 14 volts to the coach when running as well as the 110 volts. What you were experiencing was the chassis battery going dead and as the voltage dropped so did the transmission computer. It needs 12 volts to operate properly.

SCSeaside · 09-12-2021, 06:54 PM

I helped a friend with a very similar problem just a few weeks ago. Your symptoms sound very similar to his. When we checked the battery voltage with the engine running it read 11.3 volts. Should be around 13.5 volts. We shut the engine down and began by checking the serpentine belt (SB) which was frayed and had a few shiny spots on it which meant it was probably freezing or slipping. We changed the SB and restarted the engine and once again got just over 11 volts. With the engine still running, we checked the output of the Alternator which was zero volts and we noticed that the alternator was freezing which accounts for the slick spots on the SB. Replaced the alternator with one rated 50 amps higher that the OEM one. Started then engine and checked the voltage at the battery, 13.6 volts. Problemed solved. All of the above recommendations to check your connections (I recommend you do this at least once a year) are spot on. Corrosion and/or loose connections can very often mask problems and cause no end of symptoms. I installed an ignition switched volt meter in my battery compartment for a handy reference and I use dielectric grease on all my exposed connections to combat corrosion.
Good luck!

Bobp69 · 09-12-2021, 07:53 PM

We had exactly the same problem...twice. turned out it was a simple but expensive fix. Replaced the alternator and everything worked great. Next time it happened (one year later). Took it right to a wonderful shop, had the alternator replaced and never had another problem with it. BTW, the transmission will not shift when voltage is low. Don't forget to charge the chassis batteries too. Good luck.

PeterFTH · 09-12-2021, 08:34 PM

Different vehicle, same problem - 1992 Honda Accord - turns out there is a separate computer for the transmission (why? don't ask me) that went haywire. Showed me in two gears at once on the dashboard - no torque starting in 4th gear. Rock Auto on line had the computer for $135 vs Honda's $1,800 price tag. You could be having a computer issue with your Allison transmission.

Robert T · 09-14-2021, 02:25 PM

Once you find the problem, please let us know how you repaired it.

tomgauger · 09-14-2021, 04:08 PM

I had the same problem on the road in my '01 Exec several years ago. When the engine and trans went into safe mode. I used a battery booster cable with clamps on both ends to tie the two battery systems together until I could get to a service garage. The clue to do this is if everything works when you hit the battery boost switch.

wolfe10 · 09-14-2021, 04:16 PM

OP,

As you can see, we are concerned about your problem.

PLEASE, let us know what the problem/root cause are.

That will keep us from continuing do give advise AFTER you have found a solution.

THANKS.

ArtJoyce · 09-14-2021, 05:25 PM

Quote:

Originally Posted by 96 Wideglide

Wonder if your alternator has died?

That is my thoughts too. Have the chassis charging system tested. I'm going with alternator or voltage regulator, or associated wires.

Voltage drops many things will not work right.

tracsaxial · 09-14-2021, 06:18 PM

I had a similar problem and it turned out to be the fuse panel at the rear of the coach not the alternator. We had the entire fuse panel replaced along with some wires and everything worked .

John Kaehms · 09-14-2021, 09:03 PM

I have read many posts on this site. Twinboat has always given a thoughtful and accurate analysis of problems along with their solution. I would like to know his background that developed such a vast knowledge of Monaco products. He should write a book about Monaco products. Given the number of posts he has probably answered most every possible question at least once. I would enjoy meeting him and / or talking with him in person. I agree with his diagnosis of a failed alternator. Been there , done that...
Jk
2007 Monaco Cayman