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Series 60 Engine ignition off at highway speed
We are experiencing a strange behavior. After driving several hours, while climbing a decent grade, on cruise control the motor will stop, no error codes just the engine malfunction indicator and a message to check the engine at next stop. No sputtering, no loss of power, coolant level and oil are good. No high temps. I can restart the motor immediately without issue and continue. Its as if someone cut the ignition…but all the dash lights stay on. It’s happened 3 times since we left Alaska ~every 1000 miles. Always on a grade, always with cruise control on. The first time one of the ac belts had broke, so we thought perhaps that was it. I replaced it while my wife kept an eye on the bison herd. It happened again the next day but belts were fine. We stopped by prevost in Calgary, and had them check everything…codes (none), belts and replace fuel filters. We also had the fan gear (was showing oil leak), belt tensioners, belts and the idle pulley bearing and support for ac belts replaced. After a few days driving it occurred again just outside Casper Wy.
Anyone have any ideas?
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41 Replies
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As you likely learned from Prevost if you do nt have codes it is a very difficult problem to isolate.
I am throwing out a couple of ideas, both of which are nothing more than guesses so consider them as such.
Before the next drive use your manuals or access your manuals on the Prevost we site to learn how you can flash or read your codes. Practice doing it. You said the engine shuts down but the gauges remain which suggests to me as long as you do not turn the key off whatever caused the check engine light to come on may still be retained and by flashing the codes (or accessing them on your message center) you might get valuable information. That’s the best I can come up with.
But there are a lot of things that require some electrical power to make the engine run. I would want to say the ECM is losing power, but that seems inconsistent with the fact your gauges and the CEL work when the engine shuts down. But I would still do an extensive visual inspection of anything that is a wire going to an ignition or engine circuit, even though I know finding pinched wires or corroded terminals or loose connections is almost as easy as sending man to the moon.
Don’t forget……I made that stuff up.
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I’m grasping at straws here, but an off the wall thought occurred to me.
I think your coach has an alarm system and if it is like one on other Liberty’s if the alarm is set the engine will shut off or not start. I had my keys and alarm remote in my pocket and heard the doors and bays lock once. The coach was parked. It turns out something in my pocket pressed against the remote lock button. I no longer will drive with those in my pocket.
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Obviously I am revealing how frustrated I get at dealing with problems such as described and since I cannot stop trying to figure out what is going on I keep bouncing around in my brain pondering (a southern word).
My guess is this is not likely a power input issue, but might be related to an output on the ECM. Just for grins disconnect the ECM cables a few times to wipe corrosion off if that is the cause. The problem is if that is the cause you will never know for sure if it doesn’t shut down ever again.
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Maybe a bad ground?
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Long shot here, but what is your fuel level while climbing those “decent grades”? Perhaps the fuel pickup is in the front of the tank and the engine starved out? I know you said no sputtering but your issue would drive me nuts! I forgot, I already am…
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If my driveway is a clue, the fuel pickup is in the rear because with 100 gallons still on board a long range system it shut down from fuel starvation at the top of my driveway. I was backing up and the slope is around 30%.
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Thanks to everyone for the responses thus far.
Regarding fuel starve: I thought fuel and had the filters replaced. We are on highway above 1/2 tank and the grades are not that steep maybe 6%…and it starts immediately. Wouldn’t it sputter a bit to pass the air in the line?
Regarding Alarm: this was interesting as the bay door locks will occasionally take a hiatus and not work with any buttons…then at random they start working again. So I tried starting the coach and then setting the alarm while it was running. Nothing happened except for bay doors taking another vacation.
I’ll check the ECM connections. Please keep the ideas coming.
-jeff
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Generally fuel starvation is not a sudden stop like when a key is turned off. As fuel flow stops it usually is a gradual thing and usually if you take your foot off the pedal the engine continues to get enough fuel to idle. And with fuel starvation usually the engine has to be re-primed.
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It is strange that Prevost was not able to find an inactive code. It almost sounds like your ECM SW crashed while it was recording the fault. This sometimes happens with older ECMs when they encounter a fault writing to the EEPROM. But this usually is not fatal and sets the code 53. What version of DDEC do you have?
A long shot but failing belts can do strange things as they whip around the engine compartment. I had one belt unscrew the transmission dip stick as it came apart. Check that it did not damage your remote/rear start switches.
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That would be DDEC V or VI. And it is a multiplex coach so I have no clue if multiplex modules could be a pat of the ignition system.
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If it is a mutiplex system, there is a way to reboot it using breakers in the passenger side electric compartment behind the tag axle. I was told that if bus started acting funny, rebooting the entire mutiplex system might fix it.
Problem is, I don’t remember which breakers to throw. Might call prevost and ask them. They way I understood it, like rebooting a Windows computer. When all else fails, reboot.
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL -
Does it do it with the cruise control off?
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Try starting and driving the coach with the rear run switch in the rear position and see if the issue goes away. If it does it is most likely the ign switch.
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When my engine exhaust gets too high the engine shuts down exactly as you describe. This can only be seen if you have pyrometers on your dash. The first time it happened was soon after I bought the coach and encountered the long grades heading from AZ into CA. Going uphill with the cruise on the engine just shut down even though the engine water temp was not at the limit (but it was getting there!). Pulled over quickly on the hill and got it started again. Let it all cool down. Went the rest of the way up the hill in a lower gear and slower speed like the rest of the trucks!
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Apples and oranges Bill.
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