Good morning Fortravel GODS, I went to move my coach this morning backed up about 30 foot all ok tried to move forward nothing, backed up 10 foot all ok tried to move forward nothing now air brakes wont release /trans will only go into or show neutral NO codes everything seems normal other then that . What is a good place to start troubleshoot? thanks in advance Tonka
1996 u-270
8.3 cummins
build #4794
Parking brake release isn't working. The coach will back up cold with parking brake on but has to be released to move forward.
What is your air pressure? If under #60 they won't release.
Any audible or visual alarms showing on the dash?
Parking brake not releasing is a mechanical problem with air system. See question above on air pressure.
Transmission not going into gear could be a electronic problem. What is idle rpm? If idle is too high, trans will not go into gear.
Build full air pressure and try to release. If no joy, repeat and repeat again. I had a DD-3 can stick at Rocky Mountain NP on my bus. I must have tried at least 50 times when it finally released. Never did that again but I rebuilt it when I got home.
Pierce
So air pres at 120 #
HWH green travel light lit no other warnings
Park brake light lit when park brake applied goes off when released (sounds normal) can see pres drop on air gauge
RPM at about 525 at idle
Both N's are lit on allison keypad (looks normal)
So, nothing happens when you use the keypad? Pushing buttons does nothing at all? I would try pulling the pad connectors and replacing. Same with Allison computer but keypad first. Possible corrosion spray on the connectors before you plug them back in.
If pressure drops, sounds like your brakes are releasing. Don't know about yours but our coach does not need the brakes to be released for the transmission to work normally.
Pierce
A '96 U-270 has ADB-1560 not "S" cam drum
https://www.foreforums.com/index.php?action=media;sa=media;in=1701
Mike
You're right. I forgot about disk brakes, so please tell me this: Can you see the movement of the arm on the slack adjuster?
You can see the slack adjuster move
How were you able to back up if shift pad was in neutral? Or did this problem just come up after you moved the coach?
So, would you say that if it doesn't move and does after a gentle tap with a hammer it's time to service the mechanism?
And just asking out of curiosity, if you try and shift that transmission "in a hurry," will it safety out?
So the first time I backed it up and stopped it would not go forward then I moved it back another 10 feet and tried to go forward and nothing now no reverse no forward. Put Trans back in neutral ,brakes locked up Seems like both problems happened at the same time. Am I missing a connection between the 2 systems that prevents brakes to release? Just seems like more then a coincidence! Thanks for all the ideas so far.
I would take the problems one at a time and begin with the brakes.
With the wheels securely chocked, and using a helper that didn't have it in for me, I would the operating arm on each side and see if it moves when the parking brake is released, and upon application and release of the service brakes. As long as you're back there make sure the brake lights go on and off.
Has this puppy got Maxies on it?
I know little off subject, but I canceled my $1,000,000 life insurance policy after 3 attempts.
Said the man with the practically fly by wire Foretravel.
Is the transmission in your '97 U295 computer controlled?
He listed it in the beginning as
1996 u-270
8.3 cummins
build #4794
Tonka
Do you have the owners manual for the transmission? It does have electronic functions that will disable shifting if "Check Transmission" light is illuminated.
Here is a copy of the manual I got off their site. Don't know if it your specific transmission or not. It is also for the 3000 series as well.
For those of you younger than a certain age, Maxi Brakes was the trade name for the first of the spring set parking brake. Before that all a truck had was a mechanically set drum brake and wheel chocks. I *think* Maxi Brakes* came on-line in the 1970s.
Article: The Brake System – Adding Spring Brakes – Flxible Owners International (http://flxibleowners.org/article-the-brake-system-adding-spring-brakes/)
*Not to be confused the Maxie Brakes, an add on lever to help you pull your parking brake valve open.
I love reading manuals.
"NOTE: Turn off the vehicle HIGH IDLE switch, if present, before shifting from N (Neutral) to D (Drive) or R (Reverse). D (Drive) or R (Reverse) will not be attained unless the shift is made with the engine at idle. Also, be aware of other interlocks that would prevent obtaining D (Drive) or R (Reverse). Examples are "wheelchair lift not stored" and "service brakes not applied" (service brake interlock present)."
Yes. That and the AC thermostats are the only things computer controlled in that coach.
Maybe there is an air line run to the ECU or it reads a gauge?
So I just gotta ask, and it's something you would do without thinking: Is there a brake interlock? As in: Do you need to apply the service brake before shifting?
use a known good air pressure gauge and attach it to one of the drain valves on your tanks, use this to check air pressure when running engine, am thinking should be 120 plus or minus, it takes that to release the spring or Maxie Parking brakes. the 120 appox is important if you only are getting 75 you have a problem and call a mechanic
The operating pressure constantly cycles between about 90 psi to 120 psi. The spring/maxi brake button will pop out (or in depending on the brand) and the spring brake will be applied when the pressure drops into the 40 to 60 psi range. If starting up from zero pressure, the parking brake will not be able to be released until the pressure builds to approx. 60 psi. Even when it is released, the coach will not necessarily be at ride height until the pressure is up in the normal operating range.
Pierce
Nope, sometime I will have parking brake off, and put in gear with no foot on brake
The parking brake is released via a 1/4" air line running from the parking brake valve on the dash to the parking brake relay valve located on the "ceiling" behind the rear bulkhead, in the rear axle area of the coach. When the parking valve is pushed in air is sent to the relay valve which shifts and sends air to the emergency/parking side of the brake chambers, overcoming the spring pressure and thus releasing the parking brakes. (providing sufficient pressure is present)
I know of an incident where a rodent had chewed into this 1/4" air line where it exits/enters the bulkhead and not enough air pressure was available to shift the relay valve......might listen for an air leak back there with the parking valve pushed in.
You could always cage the brake chambers so it could be moved or even driven....but beware you won't have any parking brakes, have chocks and another person handy. It could be moved or driven providing you can get the transmission engaged, but at least you'll have the parking brakes released.
Thank you for the information Turbojack, I guess that takes that line of inquiry off the table.
As nice as is the 6-speed Allison, I'll keep working within the limitations of my Allison version of the Hydramatic. I have a couple of decades experience driving Cadillac limousines, first a '49 and later a '59, so early and later generation Hydramatic transmissions and my Allison 4-speed with dual lock-up feels pretty much the same.
Tonka should ask the collective how to access the fault codes with his key pad.The U270 is too heavy to push back and forth to try and get the transmission to pop into or out of gear.
In his first post, Tonka said he checked and no codes. If he did it with the up and down arrows, then it checks out. If not, indeed ask, as the procedure is simple and done from the driver's seat.
So the GODS have spoken and the trans/brake problem is fixed !!!Thank you all for the help. Only problem is I don"t really know what I fixed . I removed shift panel from (armrest) and looked for problems there. Panel looks like it had been removed/worked on before taped connections and 2 cutoff orange wires ? Tried to remove and clean connections but stopped short of pulling off plug (it did not want to cooperate) so I gave it a try and wallah bata bata bingo it worked. Not sure I had a brake problem or not, maybe trans was just hung up. So to my next Question is trans shift pad part # 29507949 Model #REM0002 SN # 2179904 is this a WTEC 1,2,or 3. I think this might be suspect also as it has acted funny before so I want to replace if not too many Bill Bucks lol. Trans is a allison MD3060R ( 6 spd with retarder ) Thanks and Thanks again for all the valuable help this forum provides ,,, TONKA
And, still no Allison codes through all of this??
AS far as I know NO codes. I pressed down on up/down arrows and got a response of d-1 d-2 d-3 d-4 d-5 but no codes. Did I miss an additional step ?
Check the Transmission Instruments web page. John Kopalek is the Allison Guru. They have some tech info on the different WTEC versions.
Transmission Instruments (https://www.transmissioninstruments.com)
If you got d-1 - -, there are no codes.
You would have to push the mode button to go from d-1 to d-2. If it progressed through the codes by itself, something "ain't rite"-- call John!
The orange wires are supposed to be cut on our coaches, if connected it is used for a remote touchpad that some trucks may use.
Probably should unplug and reconnect the cable to the keypad to make sure it is seated all the way.
John Kopalek can rebuild them much cheaper than you can source one, It will scare you what they cost. Hope your condition was just a fluke and if it happens again you should give John a call at Transmission Instruments. Nice guy and may be able to help you trouble shoot this problem over the phone.