# engine dies when 6 speed allison transmission is shifted into reverse.



## Stock Man

I have a 2003 Dutch Star on a Freighliner chassis with a Cat 330 engine and 6 speed Allison transmission.  I have a re-occuring problem with reverse gear.  Last year I when I left for a trip to Arizona when I went to back out of my spot at home as soon as I shifted into reverse the engine died immediately.  I tried it a number of times, drive gear was fine.  I had hooked up a ground wire to the black wire on the back up alarm for a ground for my tow viehicle so thought that that might be the problem.  In checking I cut off the ground wire from the horn and wiggled the wires on the backup horn and tried it again and it went into reverse. I thought that it had fixed the problem.  The next time I tried to back up at a fuel station it happend again.  I messed with the wires on the bu alarm and again it would back up.  I noticed that one of the wires seemed pinched between the horn and the frame and loosened the horn and taped up the wire.  It went into reverse.  This happend once more when I got to where I was going to stay for the winter and got in touch with Freightliner repair shop and they told me they had never heard of the problem.  I bought a new back up horn and spliced it in and it worked fine for the next 6 months during which time I had backed maybe 5 or 6 times.  I started out today and backed up from my home on a trip to Airzona and when I tried to back up to line up better in my RV space it would not back up again.  Hopefully someone else has had the problem.

Thanks,

Jim


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## try2findus

Re: engine dies when 6 speed allison transmission is shifted into reverse.

Welcome Stock Man!  I am sure there will be some brains to pick soon.  These folks on this website are a bunch of very smart RV'ers.  I thoroughly enjoy reading all of the postings.  I have recently read many posts on the Allison Transmissions, in fact there has been a post running for several years on that very subject.  Try searching the forum for Allison Transmissions and read some of that post while waiting to get a response.

Good Luck on your trip to Arizona.


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## Stock Man

Re: engine dies when 6 speed allison transmission is shifted into reverse.

Thanks Randy,

I put in a call to the Freightliner people in Chandler, AZ this evening as their is none listed in Oregon or California on the Freightliner site.  Their elex tech isn't in till morning.  If he can't help me over the phone then I will just have to be careful not to get myself boxed in, and keep going forward!!!

Jim


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## dbarton291

Re: engine dies when 6 speed allison transmission is shifted into reverse.

About the only thing the transmission itself can do to kill the engine when going into gear is having a sticking lockup clutch, or a malfunction in the solenoid circuit that controls the lockup clutch.  This would happen in both reverse and drive though.

Since drive is okay, the most likely culprit is some vehicle system that comes alive when reverse is selected.  Looking at the backup alarm is a logical thing to do.  I wonder if there's anything else that comes alive in reverse that may have an interface with the engine or its control system.  As always, a vehicle schematic would be very helpful in this situation.  

I am assuming the engine, fuel filter, etc. is in good shape also because it doesn't die when going to drive.  Sorry I can't be more specific at this point.


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## Stock Man

Re: engine dies when 6 speed allison transmission is shifted into reverse.

Engine Dies When Transmission Placed Into Reverse Problem Solved

I finally got some diagrams from Freightliner and found that the only signal that the Allison transmission gives to the transmission ecu is it give a ground to the back up relay coil.  The back up relay when energized sends voltage from the normally open contact to the backup alarm and the backup lights and also to the trailer plug to a pin which can be hooked to the trailer that is being towed if you should want the backup lights on it to work.  (I don't know why anyone would usually want to back up with the trailer connected in the first place, and if so why they would need backup lights!!)  

Because the power feed for the relay normally open contact comes from the ignition circuit (which has a 135 amp auto reset circuit breaker) if there is a short to ground anywhere on the parallel connected wires that go to the lights, backup alarm or trailer plug then a signal is sent to the data link on the engine ECM that there is an ignition problem which shuts down the engine. (A very stupid design!!!)

It should be fused separately from the ignition.  Also on some coaches the back up camera is also tied to this signal when the vehicle is shifted into reverse so a short in it will also shut down the engine.

After getting the diagrams an saw how the back up signal was fed, I pulled the backup relay out and the coach would go into reverse fine but I had no back up alarm or back up lights and the engine remained running.  Upon further checking I found that the wire going to (one of the three) tow vehicle plugs that had been installed on the coach, was not taped properly and would short out to the plug.  Because it was not shorted at all times but only intermittently the problem would go away then come back.  This was likely caused by the wires shifting in the plug when the tow vehicle was hooked up and unhooked. 

To make sure this never happens again I am going to move the back up relay contact feed circuit off of the ignition circuit and put it on another power circuit and install a properly sized fuse or circuit breaker for it.  

This problem can occur on any one of the Freighliner Motorhome Deisel Chassis Coaches so store it in your memory banks for future reference.  BTW Freighliner has known about this problem and a solution since 2002.   They have a trouble shooting paper called Solution #2082 Dated 08-14-2002.    However to my knowlege have never bothered to notify any Coach owners or fixed the problem (by adding a fuse and tie it to another feed circuit)  And in fact for over a year I have had numerous contacts with Freightliner and none of techs that I spoke to had ever heard of the problem!!!!  They might want to read their own problem solutions that are in the files.   

Now this may only appear to be an inconvienence to Coach operators according to Freightliner however I will give a couple of examples how serious the defect can really be.

Example 1.  You are driving though town and come are starting over a railroad track when the semi truck just in front of you which has already crossed the track stops, you are on the tracks so you try to back up to get clear of them.  Your engine dies and you don't know why.  Best case the semi starts moving again right away.  Worst case it doesn't move before an oncomming train reaches the crossing (and Coach).

Example 2.  You are driving through the desert and it has been raining.  You come to a rise in the road and as you start down into an arroyo you notice that there is water comming over the road at the bottom of it.  You manage to stop before getting to the flooded area but are still near the bottom.  You decide to back up to get to higher ground. Your engine dies and you don't know why.  Best case it quits raining and the water subsides and you continue on your way.   Worst case the arroyo continues to fill and you are rolled down the river.

My advice is to either move the back up relay power to another circuit, or at least locate your backup relay which should be near the transmission control unit in one of the rear hatches so you can pull it out to get going again.

Sorry this is so long.

Jim


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## dbarton291

Re: engine dies when 6 speed allison transmission is shifted into reverse.

Good catch!  With the OEM's wiring diagrams and some basic troubleshooting, many things can be made clear!


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## LEN

Re: engine dies when 6 speed allison transmission is shifted into reverse.

If you don't need to back a trailer then the same logic is, why do you need a backup horn. I back the trailer all the time thats why I have it instead of 4 down. As for backup lights on a trailer, why backup lights on anything? Whish I have docking lights too.

LEN


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## dbarton291

Re: engine dies when 6 speed allison transmission is shifted into reverse.

I think a backup warning device is most likely a legal requirement from FMVSS.  I wouldn't deactivate the system, but would fix the defect in the vehicle.  Perhaps if Freightliner is made aware of this particular issue, they can recommend how the vehicle system should be repaired or modified.


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## Stock Man

Re: engine dies when 6 speed allison transmission is shifted into reverse.

Hi Len,

Even though b/u lights and alarm are nice items to have, the point I was trying to make is that a short in a backup lamp or warning horn circuit should not kill the engine. It wasn't meant to be a judgement that no one should back a trailer.  If the power circuit for them was moved off of the ignition circuit you would simply loose the backup alarm and backup lights if a short occured. This to me would be a minor inconvienence compared to disabling the Coach until the problem located and fixed.

Good RVing to you,

Jim


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## RWW

Re: engine dies when 6 speed allison transmission is shifted into reverse.

Hello!
I also have a 2003 Dutch Star with the Cat 330 and Allison transmission. I am also having a similar problem.
When I attempt to shift the transmission out of neutral the engine immediately dies and I lose all 12 volt chassis power. No horn, headlights, ignition, etc. The gauges (tach, fuel, temp, etc.) are frozen in the position they were in when the coach was running. If the coach sits for awhile (several hours) the starting problem goes away. No warning messages and everything functions normally until I hit the "R" button on the shift console. Then everything is dead again until it has sit for several hours. I would like to get it to the shop but at this point I cannot back it out of my storage space. I hate to have it towed for obvious reasons, but especially until I know whether this is a chassis problem or an issue with the transmission. Based on your experience with your Dutch Star, do you think I might have the same problem?
Help from anyone out there would be greatly appreciated.
Thanks.


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## Stock Man

Re: engine dies when 6 speed allison transmission is shifted into reverse.

Sorry it took so long to get back to you. I haven't been monitoring the forum lately. 

Open the rear door next to the battery compartment to access the the electronics bay. Near the bottom left of the panel you will see a plastic cover. Inside you will find some relays. Remove the one market "Reverse" relay. Start your engine and see if you can now shift to reverse normally with out any problems.  When you remove the relay you will only lose your backup lights and your back up horn.  If it shifts into reverse and and the engine stays running then you have a ground on the wire that goes from the relay to either the b/u lights or the alarm. If you want I can .pdf you the wiring diagrams for the 2003 Dutch Star with the Freightliner Chassis. 

Good Luck, 

Jim


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## RWW

Re: engine dies when 6 speed allison transmission is shifted into reverse.

Thanks for the response. I have been on the road for work and unable to work on the coach until a couple of weeks ago.
Finally found my problem. It was a loose connection on the master switch. No more starting problems. I would love to have the wiring diagrams for the Dutch Star. Thanks again!


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