We are about 49 miles from our destination of Kansas City and the "Do Not Shift" Light flashes on my touchpad and the alarm sounds. Coach still drives but won't shift gears. No reverse, doesn't downshift or upshift. When I pulled into a truck stop, it would barely move from a complete stop under full throttle. Turned off coach (couldn't even put it in neutral) turn coach ignition back on and the light went out and coach shifted normally for a few minutes of driving before the light and alarm came back and the whole thing repeated itself. The fluid level looks good. I'm not overtemp...retarder is disabled years ago so it's not that....any thoughts?(https://uploads.tapatalk-cdn.com/20180314/c67220fcbe37dff0690ee576c0f449ea.jpg)
Sent from my iPhone using Tapatalk Pro
fluid ?
Fluid seems to be at a good level on dipstick. But I could add some. Problem is I have transynd in there and no transynd at the truck stop. What can I mix it with? 15w30? Dextron?
Sent from my iPhone using Tapatalk Pro
Sir,whent you start your engine,if ever you depress the fuel at the same time,this will happened.
Check if you have dirt under your fuel pedal . If yes,the pedal is not comming back at it normal idle position.
Clean every Little Rock that can go there.
It is in the limp mode Scott probably a bad ground on the DDEC engine,if you have reset the transmission
Yep. Limp mode. Every time I turn the coach off and then back on it resets and it works fine for a little while and then it does it again. I've added transmission fluid it's still behaving the same way. So where do I start looking for a bad ground related to something like this?
Sent from my iPhone using Tapatalk Pro
Do you have a dedicated grounding strap from the transmission to the frame? Are your battery cable connections clean and good? Any physical dirt in the works within the shifter button console touch pads?
Or ... like already said, physical crud somewhere in the foot throttle? Are the physical connections clean and dry. Any other poor continuity or grounding symptoms anywhere else in the Bus Conversion?
Ok I'll check
All
This. But another data point:
When it just happened, I didn't restart the bus this time to reset it. I just unplugged the touchpad only while the coach was running. This fixed it probably temporarily. Does this point to a touchpad issue?
Sent from my iPhone using Tapatalk Pro
Check the connections on the speed sensor
Are any codes present? Shut engine off. Place trans test switch "ON". Start engine. Shift from "N" to "R" and back to "N". If codes are there this will clear them. What ever you do don't rev it up and it doesn't move. You will fry a clutch pack faster then you know.
Cliff, my speedometer isn't working either all of the sudden...another clue?
Sent from my iPhone using Tapatalk Pro
You don't need to have the engine running to reset the codes, just have the key in the "on" position.
I also have an intermittent "ground" somewhere. Mine throws a "low reverse pressure switch" code sometimes. I was told this is common problem with the harness between the computer and the valve body. the guy I spoke to is an "old salty" heavy equipment Allison guy.
I have not had the time to fix mine yet, as I am not ready to dig into the valvebody and wiring.
I hope this turns out to be something easy for you, I have heard the grounding problem can be a real challenge on the ATEC.
SolarDude
I vaguely remember someone on this forum saying the speedo has a hall effect sensor somewhere on the front tires.
I know that is not helpful, I'm sure one of the experts will chime in shortly.
SolarDude
Aren't computers nice? You have to go through every harness connection, take it apart, clean the terminals, slightly crimp the female ends, put it back together and hope for the best.
Thanks Solar...I'm flying out of town for a couple weeks so I'll have to chase this down later unfortunately. Geoff, I am absolutely convinced after a mere three years of ownership that I would rather have my mechanical 6v92 and Allison HT740 back any day...seriously.
Sent from my iPhone using Tapatalk Pro
Can you tell me what an HT740D is? Specifically what does the "D" denote?
Sent from my iPhone using Tapatalk Pro
From what you have said, sure sounds like the speed sensor. That is the one on the front of the transmission.
Jack
Since you run year round in salt and slush at times, carefully inspect connections at transmission. If it turns out to be a corroded connection, after repair, securely clean and seal connection area to avoid a repeat in the future.
Quote from: Scott & Heather on March 15, 2018, 02:36:06 AM
Thanks Solar...I'm flying out of town for a couple weeks so I'll have to chase this down later unfortunately. Geoff, I am absolutely convinced after a mere three years of ownership that I would rather have my mechanical 6v92 and Allison HT740 back any day...seriously.
Sent from my iPhone using Tapatalk Pro
think about it for a second the electronics on your bus are almost 30 years old,mechanical engines and the 740 would give problems too,lol I starting to get the hang of the electronics and sorta of like it
Hey Scott,
I am in the KC area. If you need help, or you need a place for your wife and kiddos to stay if the bus is not parked in a good spot, let me know. My wife and I are a young couple and happy to help in anyway possible.
Best,
John
The majority of the issues on these older electronic engines are poor or intermittent connections. Most of the time, in the engine area, as the water, salt, road debris, gets sprayed around everywhere on the road, and over time degrades connections. Newer models have combatted most of the issues by using better connecting designs with double and triple seals on connectors, improved securement of wiring and harnesses. Be careful how you probe for resistance in wiring issues. Gone are the old days of pricking wire insulation. Quick way to introduce new corrosion point. You need to know how to use a vom meter and understand electricity and electronics to some degree. Using a scan tool is extremely useful, however you still need the meters once the scan tool points to the issue. Just throwing parts can get costly. Sometimes you are lucky. Most of the times you arent.
Best of luck! Mine did that but I went through reset and it went to neutral and the light stayed on and would not shift. New manufactured transmission; all better.
When you are dealing with a 1st generation electronic Allison all things are possible from minor to major problems and now most Allison shops don't offer much support
I chased a similar problem last summer for a while. Went through a couple of speed sensors before I found a loose pin on the plug at the sensor. Only way i was able to find it was by unplugging the harness at the trans ecu and connecting a vom and had my wife watch the meter while i started wiggling and pulling on every inch of the harness. When i got to the plug on the speed sensor the meter started going all over the place. Alison shop wanted over $600 to run a new twisted pair from the ecu to the trans sensor and new plug. 10 seconds to spread the pin with a little pick and we were off, and kept the $600.
Sent from my SM-G930T using Tapatalk
Crazy stories!! ATEC trans are crazy beasts. If it were my TPS my ddec would throw a code which it's not. So I'm leaning towards what most of you are suggesting that connections somewhere are loose or corroded cause Chessies right, we've recently been in heavy snow and salt spray. When I get back from D.C. I'll be tearing into this.
Sent from my iPhone using Tapatalk Pro
Quote from: Scott & Heather on March 15, 2018, 11:01:00 AM
When I get back from D.C. I'll be tearing into this.
Sent from my iPhone using Tapatalk Pro
Congressional hearing ? :)
Lol. No. I'm staying as far away from any politically active locations as I can. I'm there singing for some meetings for a week.
Sent from my iPhone using Tapatalk Pro
The rule, with few exceptions:
The harnesses were ALL compromised by mechanics.
30 years ago, they pricked wires with probes to solve electrical problems.
It took beatings, and retirements, to make it stop.
Some of these a$$es, and their protegés are STILL out there today, jamming sharpened probes down the back of connectors, or straight into the wires.
Those in the salt find out sooner, the rest find out later...
Re-wiring is going to figure just a prominently as insulating in the lives of busnuts, as the electronic equipped buses end up in every backyard.
Happy coaching!
Buswarrior
Happy coaching!
Buswarrior