So since they original day of purchase the cruise control has always disconnected when starting to climb a hill during downshifting. Not the end of the world but a nuisance. During our past trip me and Jim (fourdayoff) were talking about it. We both think it is transmission related causing the disconnect. You can easily hit the resume button and it engages till next shift. Never a problem till we are operating in the mountains and needing to downshift. Always reconnects and works till next shift/disconnect. Is this system connected to the ABS? All ideas are welcome short of selling coach.
Scott
Are you referring to manually downshifting?
Auto downshifting do to increased load. Also does it manually downshift when loaded up. Fine at low power settings
Any chance it is in the ECM programing? The used one you bought had to be reprogramed.
I have agree with craneman.. I know mine never drops out of cruise unintentionally...
Transmission output speed sensor?
Output speed sensor (https://www.foreforums.com/index.php?topic=37377.0)
If you have VMSpc, can you look at error code logs that might have recorded something when this occurs?
Mine won't stay in CC when the retarder is in action. Makes sense to me.
If that is the issue, it is very likely that the DIAGNOSTIC CODE is stored in the Allison ECU. Retrieve it using the Allison shift pad.
Did it with my loaner ECM when I purchased, so doughtfull
Im using the Bluefire. Does record codes but not showing any. Status unknow but will put my coach OBD scan tool and look tomorrow, but I was thinking earlier that installing my spare Allison speed sensor would be a easy troubleshooting aid?
This is normal operation. Select zero on your joystick or just turn it off. There is a workaround patch to by pass the retarder from shutting off but Ive decided keep it enabled. Some do this also to keep the brake lights from coming on with retarder.
I will contact my Allison Tech/freind and see if he still has a reader for the 4060 trans. 👍👍 that may give a direction. BUT i really didnt think it had a trans input for the cruise control, but the speed sensor probably would? Possibly getting bumped during harder downshifts? Definitely will swap in my spare sensor. Will definitely check shift pad for codes next couple of days. Great Idea I had not thought of.
Scott
Just to clarify:
Using your Allison shift pad will tell you if there is a diagnostic code (problem).
But, you will need an Allison-compatible computer to see how the ECU has been programmed.
Does the ABS have any input to the cruise control?
Yes and yes, but It probably isn't a programming issue because at lower power settings it almost always works. Never have issue with it 100 miles east of the continental divide. That ECM I installed after purchase is suppose to have the most current programming as of 2020, but who knows till we read what it is.
We didn't have it affect cruise control, but it/or the output speed sensor impacted torque converter lockup (and it didn't cause any trans codes)
Transmission seems to be hunting, 2003 U320, need help (https://www.foreforums.com/index.php?topic=22487.msg171661#msg171661)
So I was actually watching the shift indicator and it would remain in 6L, 5L, 4L. I actually have never seen it out of lockup except for 1-3? after shift followed by lockup. Almost feels like another gear.
Only disconnects when pulling hard during downshift. Immediate use of recall restores cruise control. Repeats going into 4L. Will get codes and probably install new speed sensor I carry as a spare. I probably would have continued ignoring spite the heckling from Jim that his 295 never does that. That ain't right
Torque converter should lock up mid to upper second gear and all higher gears under normal driving conditions.
So you should feel 1-2-2 lock up-3-4-5-6 with torque converter always locked in 3-6.
The only thing that takes my trans out of cruise is stepping on the brakes or putting on the retarder
or shutting it off with the switch. I believe that the brake light is what takes it out of cruise and if the
retarded doesn't turn on the brake lights it won't take it out of cruise.