same problem ,different dayI ----Well almost!

[bigred]

Some of you may remember the problem I had with the HT555 transmission in my 94 Prevost refusing to go into any gear then after 2 tows found someone that would work on it but  could not find anything wrong .Due to health problems with family and now with myself it has been driven very little the last two years but the tranny has worked flawlessly up until the other day. Went to the storage lot ,fired it up and started to go through the gears hit first and nothing .It was the same with all the others .The difference this time . 

[luvrbus]

Under the drivers window in the bottom door check your fuse and the connections on the ECU  does the pad light up ?,Prevost mounted the ECU in a dumb place IMO

[bigred]

It does light up.When I was writing this the my computer locked up and I kinda did not get the info out. ,The one difference between this time and before is this time the DNS light is on . I have the Prevost manual with the codes but so far I have not found where to read the dots .I am thinking I need a service man with a scan tool ,not a easy find around here.

[luvrbus]

DNS is low voltage it could be several things causing it check the voltage and clean the plugs and terminal including the ground on your ECU it should go then

[bigred]

Cliff:It finally stopped raining long enough for me to get out to the old CC .I got my trusty can of contact cleaner and some fine sand paper and headed out but unless cc burred the ATC behind a bunch of stuff ,I don't see it.There is a thing in the engine compartment that looks like an ATC BUT IT ONLY HAS A FEW WIRES CONNECTED TO IT .Do you think  CC may have located it else where ?? the way the Prevost is laid out the top part of the compartment has the CB'S  .and other electronic components .The bottom has the front brakes ,burglar alarm ,the ATC and and another test switch and the main circuit board that controls the lighting .   i

[luvrbus]

Cliff:It finally stopped raining long enough for me to get out to the old CC .I got my trusty can of contact cleaner and some fine sand paper and headed out but unless cc burred the ATC behind a bunch of stuff ,I don't see it.There is a thing in the engine compartment that looks like an ATC BUT IT ONLY HAS A FEW WIRES CONNECTED TO IT .Do you think  CC may have located it else where ?? the way the Prevost is laid out the top part of the compartment has the CB'S  .and other electronic components .The bottom has the front brakes ,burglar alarm ,the ATC and and another test switch and the main circuit board that controls the lighting .   i

Under the drivers window is the only place I ever saw one Joe's Country Coach Prevost is there and is the same vintage as yours.The ECM is never very far away from the shift pad ,my CC  with the World Allison is under the drivers window too ,I do have a test port at the rear.CC wiring can get wild though lol I had to get Jerry and Van to trace a wire for my dump valves I could never find the fuse,I pulled every fuse and checked them,lol the fuse was tagged wrong and was in the spare fuse slot ,Be thankful you don't have the multiplex wiring like I have it is way above my pay grade

[bigred]

I think CC has struck again !!  Evidently their penchant for cramming as much as possible into as little room as possible . I'm convinced that you are correct ! .I haven't found it yet but I will pull that big old windshield washer out and see if that will shed light on the subject, I do appreciate all the help that you give to me and others on here . You don't realize how valuable you have become since my bus shop closed because of health reason's (the owners) .Beautiful 5 bay shop with two pits and there is now a heating a cooling outfit in there .Enough to make a man cry!! LOL

[luvrbus]

Van is going to post a photo of the location it is under a cover maybe at the top,be sure your house batteries are on CC wired the limter module to coach batteries and if doesn't read 600 rpm it won't shift Van can tell you the number of the wire to cut and ground to bypass that crap

[Van]

Our friend Ron has a CC XL within a few years of yours and had the very same issues some 4 years ago. I got him to call Prevost in Quebec. After talking to one of the oldtime employees there the issue was an inhibit switch that had gone bad, this switch detects high rpms (600 and above) preventing the shiftpad from placing the transmission in gear and does go bad after time and is no longer available or used by  Prevost. The switch is housed in a small black box (see pics) the work around was to take yellow wire #222 coming from the black module and ground it (see photo). The transmission computer (ATEC) is located in the front electrical compartment below the drivers area in a metal box that has 4 Zuess fasteners and was located there by Pevo not CC, CC did however wire the ATEC 12vdc switched power wire to the master house battery switch in the drivers overhead console in Ron's 89'XL, YOURS MAY BE SIMILAR and worth the check😉. Of course make sure all your fluids are up to snuff as well the chassis and house batts.
Pic1-atec box location.
Pic2- wire 222 now sent to ground.
Pic3- inhibit switch module (black).
Pic4- wire #222.
Good luck!

[luvrbus]

There you have it Big Red the limit box if it doesn't read between 500 to 600 rpm you are dead in the water, Eagle tried that on the 741 Allisons. The generation WT 1 B500 used something similar called the VIM module it was a PITA too   

[bigred]

Thank's Guy's :Between rains I have found the ATC. After pulling that huge windshield washer reservoir .I found it in the right rear of the bottom compartment. The 222 wire may have already been shorted .There is a yellow wire hooked to a black wire .but the brady wire markers are getting very fragile after thirty years and the one on this jumped wire is gone .Neither one of the ends look like Van's pics ,but I will have to work on this a bit more .In case this is not the 222 wire ,how do you get the atc to reset after a high rpm'The reason I am asking this is I was trying to ad just the drivers seat and hit the accelerator by mistake .Don 't know how high the RPM'S  got to but it was screaming at me .The dns came on right about this  same time .I keep going back over things that happened around this time frame. Hate to keep bothering you folks ,but I sure do thank you for your help!

[luvrbus]

What is the temperatures where you live,those transmission will lock out all shifting if the oil temperature is 25 to 30 degrees, if your engine is a DDEC the only thing that would cause a over speed would be long idling causing fuel build up inside the air box then they will go into orbit when you give one throttle.When I get time later I will check my 700 manual to see if there is a reset but I don't recall one,Check wire 203 (12v or 24v) it connects directly to the battery and it is the wire (fused) to the ECU the shift pad has another power supply.you have a 700 ATEC troubleshooting manual ?

[bigred]

I live in N C  Cliff.IT does get cold but doesn't stay that way long;Night before last it got down to 50.Last night it down to 23 .Tomorrow iit is supposed to top out around 70.It has never been started started in temp below 20.At least not while I have had it .. 

[TomC]

I sure love my Cat 3406B and Allison HT740 both non electronic. Good Luck, TomC

[luvrbus]

I sure love my Cat 3406B and Allison HT740 both non electronic. Good Luck, TomC

When RV's are used and driven everyday the electronics don't give you many problems, converters always do something stupid. I been chasing a problem with my electric sewer dump I knew it had to be a fuse but it took Van and Jerry a day to find the fuse. I wore the fuses out testing and changing all the fuses only to find out after they traced the wring County Coach had the fuse labeled in the spare fuse slot the only one I never pulled. I am now a proud owner of a good tracer/toner, the Habor Freight toner went in the trash can.LOL I never could get my bay lights to work that was a simple fix if you turn those on inside the coach they work fine when you open the doors