iRV2 Forums

iRV2 Forums (
-   Class A Motorhome Discussions (
-   -   Allison Transmision Cruise Control (

Dj Michaels 01-19-2012 11:00 PM

Allison Transmision Cruise Control
Just shortly before finishing my last trip I stop for diesel and after I got back on I-40 my engine began to cut out and the speedometer needle peged all the way to the right and back to 65 mph where I set my cruise.

That went on for a few miles cutting in and out and the needle jumping back and forth. I cut off the cruise control and the engine smoothed out. I reset the cruise and the problem started up again. I left the cruise off and the engine ran fine but the needle would still peg from time to time. I first thought bad fuel but I now wonder if there is a sensor or valve going bad. Anyone got any Ideas?

Dj Michaels

Mr_D 01-19-2012 11:04 PM

What engine/transmission/chassis maker?

Normally the cruise control is part of the chassis and not the transmission/engine package

Dj Michaels 01-20-2012 10:25 PM

I have a 300 HP Cummins, Freightliner Chassis, and the Trans is an allison
6 speed. I called Allison who said that it could be the speed control sensor. From all I can gather you are correct in that it is a chassis problem and not trans. Also it was suggusted that it could be in the wiring and that road vibration might have caused a loose connection.
I will take the MH out on I-55 and try it again to see if it happens again. If not then it won't do me much good to have it looked at. Do you know where the Speed Control Sensor might be located generally?


Mr_D 01-20-2012 10:38 PM

That is one thing I've never had a problem with. If that's the case it might be an Allison problem.

PyrateSilly 01-20-2012 10:49 PM

What year is your coach? What manufacturer is the cruise control? I ask cause IF it is the cc going bad and it is a Bendix you will either have to try to find parts for since they are no longer supporting the old ones or you will have to totally replace it.
We had a problem with ours and happened to find the part to fix it for $75 instead of replacing for over $500. If you do have a Bendix I can email you the manuals and stuff I have on it.
I will say that fixing it also fixed the ABS light so that it no longer stays on. Weird I know but thats what fixed it.

Airtool 01-20-2012 11:11 PM

Jumpy speedometer
1 Attachment(s)
This may sound crazy,but I had the same issue on my freightliner chassis.
It turned out to be a bad ground connection in the alternator area.
Tack reading stayed at a constant 1900 rpm and the speedometer went to well over 100mph.
Freightliner also mentioned the sensor,I replaced it No Joy.
Shortly after correcting the ground issue the Alternator regulator failed. This has happened twice and the second time the Speedometer would jump
around when idling,grounds checked out,but the voltage regulator tuned out to be arcing to the alternator housing internally. See Attached photo. The small pit marks around the mounting holes should not be there!!!
I have had times when running on cruse that the speed would surge,by dropping like 2-5 mph and then surge up to +2mph over the set speed only to drop back down. Disengaged the cruse and everything ran smooth as silk.
That problem turned out to be a corroded contact in the cable connection at the engine ECM module.


Dj Michaels 01-20-2012 11:14 PM

Cruise Control
I have a 2001 Damon diesel and I haven't had time to track down the make of the CC. Should I find that the problem is the CC and that it is a Bendix CC then I will most surely be back with you for your info. What I thought was an engine miss must have been a false signal being sent to the injectors causing the engine to lurch or miss fire. Either way it get your attention.



Dj Michaels 01-20-2012 11:24 PM

Funny you should mention the alternator because I just replaced my two cranking batteries and the engine still drags when I first try to start it up and other times is turns over faster. I was thinking maybe the starter was going out or maybe the alternator isn't charging the batteries properly. Where was the ground problem located?

Dj Michaels 01-20-2012 11:31 PM


I went back and read you post again and saw where you said where the ground problem was. My fault. I have a family member who works for cummins and I will show him you post and have him check that out. By chance when you experienced you problem did it seem that you engine was missing or what I felt was a hard miss as if it had bad fuel and wasn't going to continue running.


PyrateSilly 01-21-2012 01:07 AM

2001? I can almost guarentee that you do NOT have Bendix, but you never know. Go thru all grounds and make sure they are tightened down. Some on ours were very loose.

Airtool 01-21-2012 08:37 AM

Mike ! With a 2001 and Cummings Engine you should have a Bosh VP-44 injector pump.
If this is the case, then some items come to mind.
I mentioned the ECM connector and the Alternator issues.
The Starter could be an issue, but check the connections on the starter and the starter relay. The relay is generally mounted close to the starter on the Main Chassis frame. Many refer to it as a Castle Relay because of its shape.
When where the fuel filters changed last?
How many miles on the coach? The lift pump could cause hard starting because its output pressure is low.
The other bad thing about a falling lift pump. When the output pressure drops below 5psi. this can starve the injector pump of fuel. The fuel is used to cool the injector pump and its control circuit board and can cause the injector pump to fail.
I installed a fuel pressure sensor so I know when the fuel pressure drops below 5psi. handy because I know that I have a problem with filters or the lift pump and that keeps me from causing serious damage to the Injector Pump.
At around $3000.00 to R & R with a new one. I'm trying to stay away from that bill as long as possible.

Dj Michaels 01-31-2012 11:37 AM

Thanks to all who replied
I read everyone's response to my problem with the cruise control and my diesel engine appearing to miss while using the cc.

Just to see if it was still happing I went for a ride on I-55 and to my great joy it didn't happen again. It appears for the time being that it was one of those grimlins in the system. Again thanks for all your help.


bingo1492 02-03-2012 01:49 PM

criuse control problem
:banghead:got a '95 safari, sahara a pamplet about ROSTRA CRUISE CONTROL...looks to have been installed when built...worked good when i bought it 2-3 years ago..began to work intermittenly...last time out would not work at all...the booklet shows this programming switches thing with a LED indicator and i don't know where that is located...or if its a seperate thing that is not with RV..don't know if its in the wiring harness or what...will check grounds and come back...anyone with that brand of control...

Airtool 02-04-2012 12:50 AM

Bingo ! This problem will pop up when there is a bad connection (Corroded Contact) or bad ground connection. This causes the coach to surge when in cruse also.
My problem was a bad connection at the ECM interface. Removed the cable and reinstalled it. That helped for a time. Had to remove it and clean the connections with some contact cleaner and reinstalled. That repair is still holding.
If you are not real careful you can damage the contacts, they are small and allot of them. Generating a bill you do not want !!!!

All times are GMT -6. The time now is 07:20 AM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.