On my 95 U240 I have the Bendix Air Cruise Control(same one as in Chuck's post Throttle Cable Questions). If the cruise goes to full throttle climbing a hill, it will lock/freeze/get hung at full throttle. In normal driving the cruise works fine, even on freeway with small hills and overpasses. The throttle control functions works fine. If the cruise gets hung, the only thing that will release the cruise is repeatedly using the throttle air pedal, going from full throttle to idle. Turning off the cruise has no effect. Using the air service brake slows the MH, but does not release cruise(normally it does). Sometimes it has stayed hung for up to 5 minutes, before releasing. My throttle cable from the cc-5 air cylinder is good and works freely. Air always works fine. I thought the problem would be in the throttle cable, but it is not. Any Ideas??
Pat,
Pat,
There is a snister (sp) bronze exhaust port "filter". Remove and clean it. If debris get in it, it will not release air which means the throttle will not release.
Brett
Wow, what a forum, only 7 minutes for an answer that lots of us needed to know. Thanks Brett!
would the snister (sp) bronze exhaust port "filter" be used during normal operation? The cruise works fine, except the release from full throttle. Normally the cruise will engage, release, resume, coast, release with brake, speed up with no problems. The only problem is after full throttle speed acceleration/maintenance on steep hills?
Pat,
Pat,
Sure, there could be other causes. But, after full throttle application (like after topping a grade and beginning to descend) is when you need the air released most quickly. So, if it is clogged, this is where it will show up first.
Sintered. (No offense, Brett)
None taken. That is why I put the (sp) after it. Probably only slightly better than saying bronze "thingy" screwed into the bottom of the whatchamacallit.
Pat, I have gone thru that problem with the 95 240 I had and here may be your answer as well.
1- CC air cylinder may be hanging up inside so remove , take apart and grease.
2- The throttle pedal may also be sticking on the pivot pin, which I found very possible. If you too have carpet tucked around this area use a knife and cut it away from base and either take pin off and clean and lube( the spring/pin is a Bitch to get back in as it is awkward), but first try and spray some lube onto pin and spring. After I did these things the idle acted correctly as it should. I think you have the same problems I did and we had that problem all the way from Dallas to home 3000 miles-scary.
I am sure this is problem.
JohnH
If the bronze "thingy" isn't plugged up, and the pedal isn't sticking, perhaps the next item to check is the cable end linkage pieces on the throttle control cable bracket? I know on mine they were pretty corroded and dirty. It might be they work OK in the "normal" range of throttle movement, but when forced to the extreme end of travel by full throttle application, perhaps something is getting hung up? Just guessing, here.
And while we're on that subject, what is a good lubricant (if any) for that type of device (throttle levers, links, cables, etc)? Brett - John - any suggestions?
Dont know the technical side of this, so I will tell you the human side from our 88.
Had similar issue, intermittent at best. Realized after the DW says scoot the floor mat back, the pedal was sticking, check around the back side I had a pecan shell stuck. :-\
First time it happened :o scary!
Just
Thanks for all the ideas. I do have one new question: How does the air throttle pedal control the cc-5 air cylinder of the cruise control? or does it?
The air throttle pedal works correctly all the time. No problems with sticky throttle. The problem only occurs with cruise control engaged and after full throttle application.
I am thinking now that if the bronze "thingy" screwed into the bottom of the whatchamacallit is cleaned and not the problem, it must be what JohnH said: 1- CC air cylinder may be hanging up inside so remove , take apart and grease.
Pat,
It is so easy to take apart and do the clean and grease that I would not bypass that op'.
Be care ful with the O rings removal and you may still be able to use old ones once greased.
Check the resistances as in manual for connectors. Oil the cable, and do the linkage at pump ( I used lithium grease spray).
I have a suspicion that the pedal was also "hanging up" as mentioned and not allowing air valve to properly exhaust, so definitly spray the pin etc in the back of pedal.
The grease I used for cc5 cylinder was the one thatis used for the Bendix Air Dryer parts but any synthetic or light grease should work fine using your finger to lightly smear on walls etc.
JohnH
Pat,
Do you have a air system schematic for your coach? I hope you do, along with a complete set of owner's manuals.
On my coach, there are 3 air lines coming from under the coach up to the Bendix panel on the forward firewall of my engine compartment. Those lines are numbered 6, 11 and 41. According to my schematic, line #6 originates just downstream of the "Protection Valve" at the "Rear" air tank (the one that supplies the rear brakes). From there it goes directly to "Cruise Control". Line #11 originates at the "Throttle Valve" (the gas pedal), and goes directly to "Cruise Control". Line #41 comes off the air line that connects the "Service Brake Relay Valve" to the "Spring Brake Relay Valve", and goes direct to "Cruise Control".
From the input of those 3 air lines, the Bendix brain somehow determines what throttle setting you want, and supplies it. I'd say #6 supplies the operating pressure, #11 is a "variable" signal depending on how hard you mash the gas pedal, and #41 tells it when you hit the brakes. Sound logical to you? I'm no expert on this stuff, but I like to study the diagrams and try to understand how things work...
The inversion valve is what determines which controls the throttle, the cruise control or the foot pedal.
Thanks Chuck for the info on the air system. I looked today in my books and I don't have the air schematic. I do have a bendix cruise control book. I did the CC-5 air cylinder R&R today. All parts looked good with no problems during the R&R. The throttle control works fine. The pedal throttle works fine. I did not take it out for a road test today, it was wet and rainy, BTW I got 5.31" over last night.
The problem I am having must not be caused by the CC-5 air cylinder, I do full throttle take offs all the time and I have never had any throttle hangs during non-cruise operation. I thought that the CC-5 air cylinder was only used for cruise control, but now I know that it works for both cruise and manual pedal operation.
What could cause the hang(cruise at full throttle after a up hill grade) if the only thing that will cause it to release is to use the manual throttle pedal going from full throttle to idle very rapidly many times???
Thanks for all the help!!
Pat,
Pat,
This is a real puzzle. I'm scratching my head trying to deduce what would be hanging up. No brilliant ideas yet. Here is a scan of my air system schematic. Your coach may be slightly different, but perhaps this will be helpful, if not on this problem then in the future. I'll keep thinking about your puzzle!
Hmmm?
Did you lube the linkage at the pump and the shaft that goes down in the pump?
Did you check all the connection resistances esp' the cc5 cylinder potentiometer as shown in manual?Did you spray a lube on the pedal shaft pin and no carpet is causing a hang up?
If you did not take it for a test how do you know it is not working correctly now? Looks are very deceiving on this one.
JohnH
I'm going along with John on this, since he seems to think the problem is mechanical in nature. Reading through the Bendix manual, including the trouble shooting section (link below), tells me that you are using all the components of the cruise control system BOTH when using cruise AND when applying throttle inputs manually. Your manual throttle works fine, even when you apply "full throttle". Also, when you have the "problem" during cruise operation, the system is ignoring 3 separate inputs that should cause it to disengage: power switch off, brake application (brake light switch on), heavier brake application (brake pressure override signal). All 3 of these signals function correctly during normal cruise operation, except when the "problem" occurs.
So the question boils down to: What factor/component comes into play ONLY when the the cruise control calls for "full throttle", but is NOT in play when manual gas pedal movement calls for full throttle? This is the question that has me stumped.
I will get out today and study my coach setup. I can't remember where the "manual throttle input" (air line #11 on my coach) ties into the system. It is not shown on the diagram in the Bendix manual referenced below. Perhaps this will help me understand how this thing works.
I'll be interested, Like John, in the results of another test drive, since you cleaned the air cylinder. Where do you find hills steep enough (in East Texas) to cause the cruise control to request full throttle? I thought it was pretty flat over there...
http://www.wanderlodgeownersgroup.com/downloads/BendixCruiseCtlManual_Parts.pdf (http://www.wanderlodgeownersgroup.com/downloads/BendixCruiseCtlManual_Parts.pdf)
Good Morning JohnH & Chuck, Thanks for all the help on this problem. I would enjoy visiting in person with ya'll. We would get to it quick. John I only cleaned the CC-5 air cylinder. I like to do only one thing at a time when dealing with things like this. I should have, but did not checked the electrical items you mention. I have checked the throttle pedal for the carpet under it and lube the pin issue and that is solved. The only tests I have done is to use the throttle control function and it works(fast idle steps up with repeated resume button, max RPM 1300). The manual throttle pedal respones correctly.
Chuck I agree with everything you said. I think you got it
So the question boils down to: What factor/component comes into play ONLY when the the cruise control calls for "full throttle", but is NOT in play when manual gas pedal movement calls for full throttle? This is the question that has me stumped.
I will drive today to get diesel and I will test the cruise in all ways except for the full throttle issue. That really scares me when it hangs at full throttle.
I live in Lufkin,Texas. Drive north toward Nacogdoches, Texas, FOT home, and if I tow there are a couple of hills that will need full throttle to maintain 60MPH. Just outside of nacogdoches there is one hill that is very steep. It will test any MH. Around Jacksonville, Texas there are hills. One I need to use the retarder going down.
Thanks again john and chuck, onward thru the fog!!
Pat,
Scary?...Foretravel drivers are supposed to be fearless!
Here's what you need to do: Take the coach out, find a big hill, set the cruise control and
wait for the throttle to stick. Turn off the ignition as you crest the top of the hill, put gear selector in neutral and coast/brake to a controlled stop, pulling off the road at a safe spot. Then go back and lift up the bed and see
what the heck is stuck!
I'll be sitting here (safely) at my desk, waiting to hear your report. GOOD LUCK!
I went for the test drive and diesel fill up(3.699/gal). All take offs were at full throttle with no problems/hangs. I used the cruise which maintained speed perfectly, resume, accelerate, coast all worked correctly. Turn off and brake release both worked correctly. Resume from 40MPH to set speed 57MPH worked correctly. In All test everything work perfectly.
I wonder about the test you suggest, around here there will be no place to pull off and stop. You would think that the throttle would be full/wide open. I would need to know if air is still applied to the CC-5. I would be able to see that the throttle is full/wide open. If their is air in the CC-5 then the problem could be electrical/control, but if no air on CC-5, then the CC_5, or cable, or.. would be the problem. I am thinking that all components are working in normal conditions/level road.
I had an 84 foretravel with the 3208 cat with the bendix cruise control and it did the same thing for me when I was coming into Knoxville Tn from the north. I shut off the engine and could hear air escaping when I open the engine cover. I used something to hit the solenoid that is mounted on the control box for the bendix and the escaping air stopped and the throttle returned to idle position. It only happened that one time. I usually turned off the cruise control if I was going up hills that required full throttle for an extended time and never had any more issues.
My Test suggestion was, of course, mostly "tongue-in-cheek", but my DW (practical Lady that she is) also reminded me of a potential problem: when you turn the ignition off you would lose your power steering. That would not be a good idea - I have read that these coaches can be a handful using only Arm-Strong assist!
Well, I still don't have a solution to your "sticky throttle" problem, but I have finally figured out how the air throttle integrates into the Bendix cruise control.
By studying my coach setup, and comparing to the diagram in the Bendix manual (link in earlier post), I could see how the throttle air line ties in. I will have to disagree with Ron, who said (in a post above) that the "TR-3 Inversion Valve" determines what has control of the engine, cruise control or foot pedal. Actually, this function is handled by a additional valve not present in the basic cruise control setup: the "DC-4 Shuttle Valve". I will include below a "marked up" copy of the cruise control diagram from the Bendix manual. In my amended diagram, you will see the added DC-4 valve is installed between the TR-3 Inversion Valve and the CC-5 Air Cylinder. The shuttle valve has two inputs and one output - whichever input pressure is HIGHER will be output by the valve. This is why your gas pedal still works, even when cruise control is active. If the "gas pedal" input pressure is higher than the "cruise control" input pressure, the gas pedal wins and you will accelerate above the speed set by the cruise control!
By studying my diagram, you will see that this is a pretty simple, and rather elegant, engine control system. The only real drawback is the fact that (at least on my coach) when you first start up the engine you do not have throttle control until air pressure builds to around 50-60 psig.
Chuck, If I understand your diagram then even if the electronics on the CC are toast you would still have throttle control via the Treadle. Sound right ? Reason I think this way is that on my former 95 I lost function of the cc for a period but still had full throttle control with the treadle. Later I cleaned up the contacts and all was good again. My imagination maybe that it worked ?
Gary B
Gary,
I would say you are correct - throttle will operate totally independent of cruise control. The DC-4 shuttle valve is completely mechanical in operation - so it will pass through the pressure from the throttle valve whether the cruise control is dead or alive. Another nice feature of the system!
I haven't studied the throttle valve (gas pedal) setup, yet. Need to do that. I assume the throttle valve must have a built-in "exhaust" function, so that line pressure is reduced as you let up on the gas pedal. Otherwise the CC-5 Air Cylinder would not be able to retract (return to idle position) when you were operating on "Air Throttle" only.
I just looked for my comments on this issue but it must have been on another thread. I am relating to my suggestion of removing-one at a time- and cleaning all the valves in this system as you could have one "hanging up" so to speak as Red Tractor did. I cleaned each one up and made sure they worked correctly.
JohnH
Thanks to chuck,john, and gary for the great input. It amazes me that both systems(manual and cruise) work perfectly except for this one situation(full throttle cruise). Chuck, is your dc-4 value mounted at the bendix cruise control or some where else? I believe mine is just to the right of the ca-1 module. I will have to double check on that.
My DC-4 is mounted directly above the Bendix "brain", and below the CC-5 cylinder. See photo below. I think yours is in the same place.
Also just something interesting I noticed in this photo: the Bendix box has lettering on it that says "U280 E14". Done at the factory, I assume. That is the same notation found on my factory Air System schematic (which I posted earlier in this thread).
I always wondered why I had no throttle control on initial start up, thought it was a engine temp safety thing.
Roland
Good Morning Chuck,
Your cruise control board looks like mine. Here's my pic. I am stumped. I am beginning to wonder if there could be some other type of issue other than mechanically stuck. Everything works fine, but....
I have included a pic of the other end of the throttle cable. I wonder if there is some way this stuff could get stuck????
Thanks again for all the help. I am going to Colorado on the 31st. so today i am going to fill up on propane. I will use the cruise and all functions of it. All take offs will be full throttle. Updates after propane run!!
Pat,
Roland,
Actually, I may have been overly pessimistic in my comment about throttle control at startup. I was actually thinking about MY coach and how it acts. Apparently yours works the same way. Some owners may experience a different behavior. The air supply for the throttle comes off a common line between the "FRONT" tank and the "REAR" tank. If all the one-way valves, protection valves and control valves in the air system are sealing perfectly, then the air pressure in those tanks could hold up for a LONG time after the engine is shut down. If that were the case, throttle control would be available immediately after the engine is started. I work toward the day this will be true on my coach!
(I amended my original comment to refer only to my personal experience)
Pat,
"I wonder if there is some way this stuff could get stuck????"
"Sticking Linkage" at the end of the cables was my very first guess back at the beginning of this thread. But since it never happens when you apply full throttle with the foot pedal, I think we have pretty much eliminated that possibility.
"All take offs will be full throttle."
You must get terrible fuel mileage!
Good luck on your trip to Colorado. If it was me, I would avoid using Cruise Control on the big uphill runs, until you get this problem sorted out!
Chuck, I agree with everything you said, except for the fact about my gas mileage. I get 10MPG towing or not, I drive 60MPH. I will only use the cruise on level ground and only overpasses on the coming trip.
On the startup throttle control, mine always starts and rpms go up to about 8-9 hundred, then falls off to 7 hundred and stays there. My MH holds air for a day or two.
Pat,
On the 240 I too noticed no throttle control till air built up, but agree if you have air in tank it should operate normally.
Pat, maybe I missed this earlier but I do not remember seeing in your posts (after cleaning cc-5etc) that you actually tried to replicate the problem and that it did actually still hung up. I am still sure that you have the same problem we had for 3000 miles (sticking fast idle). I even tied a piece of rope on throttle cable and ran it thru coach so I could pull on it when needed to slow engine--but that did not help! It only stopped doing it after ALL valves/cylinder and linkage, plus throttle pedal cleanup happened. It never came back even on the 700 km trip to Alberta, so I know it fixed it.
Again, have you taken apart all the valving etc and done the resistance checks in manual. PLus spray lube all over the linkage at pump and some release oil on the pivot shaft.
JohnH
Great information from you all! I will be doing some of maintance issues you all have suggested once we get home. Yesterday my Bendix began acting up....it will set but then after about a minute it pulses up and down. It will not hold a steady speed. At first I thought it was a road quality issue, nope. I guess a lube a clean out is in order. It's gonna be a long drive to MI from NY tomorrow lol
Jeff
to JohnH: I have not tried to reproduce the full throttle hang(I am a little scared to). I have only cleaned the CC-5 air cylinder, checked the throttle cable for binding/sticking. I have driven the MH 2 times since cleaning. Both times: full throttle take offs, used all cruise functions(level ground except for overpasses on loop). All cruise functions work perfectly, throttle control works perfectly, manual throttle control is perfect. All of the previous cruise throttle hangs have been by mistake/forgetting the cruise is on until it is to late to turn it off. After all hangs were gotten to release by using the manual throttle pedal going from wide open to idle(service brake application & turning cruise off had not effect) , the cruise works fine.
Jeff: I think finding solutions to problems is very easy after you have defined and understand the problem. Then I think you should only change/repair/replace one thing at a time. If you use the shotgun method of trouble shooting, you may not know what the fix was, you may also not understand the problem like you thought you did. I also think you should not fix it, if it is not broken.
I am still looking/working on the problem. I wish I could think of a way to test my issue without killing me or other folks on the road.
Pat,
Jeff,
If you have not already done so, I recommend reading through the
entire Bendix manual (link below). You will get a good understanding of the system, and be more confident when you attempt repairs. On page 22, there is a discussion about "Surging", which sounds to me like what you are describing. Good Luck!
http://www.wanderlodgeownersgroup.com/downloads/BendixCruiseCtlManual_Parts.pdf (http://www.wanderlodgeownersgroup.com/downloads/BendixCruiseCtlManual_Parts.pdf)
Thank you Chuck...this is my bedtime reading material tonight. Since I'm off work tomorrow after the dentist I'm going to start this project.