2003 U320, joystick on retarder moved to any on position (pulled back), and today it did not turn off the cruise control (or retard). Retarder master switch is on. Once cruise is turned off, retarder works effectively.
If I first turned off cruise via cancel, cruise off, or by hitting service brakes, retarder then worked as usual. Prior to todays travel, it killed the cruise and worked immediately as retarder.
Thoughts? Some type of sensor just below the joy stick?
Edit: I should add, that previously in cruise, with joystick pulled back, the retarder did not activate and kill cruise control until at zero throttle (IE, downhill, cruise lets throttle go to zero position).
So if I forgot at last stop to push the joystick forward, I could accelerate and engage cruise. Next large downgrade and cruise let throttle go to zero - that is when the retarder engaged and killed cruise.
No big deal, all works well either way. I figure a loose or corroded connection, been on some bumpy roads the past 3 days. I'll check some connections when I have time.
That's the way mine works.
Which way is that, Bob, the way Dan thinks it should or way is acting now? Ours only begins to retard if we begin to drop in speed as when coasting and then start slowing going up a hill. I can leave the joystick in any position and as long as our speed isn't dropping as described then it is just joyfully along for the ride.
Dan,
I think that is the normal function. Your experience is how mine works as well. Cruise control must act to always supply a touch of accelerator, which means the retarder won't engage. Same as if you pull back the retarder while your foot is on the gas pedal.
If you go down a very steep hill with both cruise control and the retarder joystick pulled back a notch or two, occasionally the cruise control will back completely off the gas, the retarder will actually engage at that point (and cancel the cruise control).
I believe you are right.
I added this to my first post above:
Edit: I should add, that previously in cruise, with joystick pulled back, the retarder did not activate and kill cruise control until at zero throttle (IE, downhill, cruise lets throttle go to zero position).
So if I forgot at last stop to push the joystick forward, I could accelerate and engage cruise. Next large downgrade and cruise let throttle go to zero - that is when the retarder engaged and killed cruise.
No big deal, all works well either way. I figure a loose or corroded connection, been on some bumpy roads the past 3 days. I'll check some connections when I have time.
There isn't any chance something was blocking the accelerator's return to "rest", is there? Like a creeping floor mat or a binding pivot on the pedal itself? I vaguely recall discussion of this a few years ago (but can't immediately find it).
You may be right. I'll check that. That or cruise didn't quite release to zero throttle on a hard downhill run until I turned cruise off.
Not my request but you seem to not have driven a Allison retarder equipped coach.
Twice as strong as the best Jake.
Serious deceleration. Before I was sure the brake lights actually came on I would look in the mirrors and rear camera to verify no one was close it I intended hard retarder use.
Rarely go past three out of six positions on 10% downgrades. Four on 13% on monarch pass in Colorado.
I run two position on bumper to bumper slow and go la freeways as accelerate, coast and braking only require one foot.
I do turn the retarder off regularly and apply hard brake pedal to warm up the brakes and deglaze them after sitting.
Most local driving I do not use the retarder. Just exercise the disk brakes to verify they are ready and able at all times.