Bus Engine Shutdown

One of our group experienced an engine shutdown while driving, and it has gotten me to thinking.

The first reaction is that our coaches will not shut down without warning, but the time to react is very limited. If you get an indicator light to advise you the coach will shut down, you have literaly seconds to respond. You can over ride the shut down feature by pressing the override switch (it has a red colored square) which will provide you with a few more seconds to get off the road and to a safe place.

But beyond getting off the highway and in a safe spot now what do you do?

There are only three malfunctions that will make you shut down.

43...LOW COOLANT LEVEL
44...OIL OR COOLANT HIGH TEMPERATURE
45...LOW OIL PRESSURE.

There are many other codes, but none of the others will shut you down.

It has been my experience and this opinion has been reinforced by anecdotal evidence that usually the sensor has failed in some way. If you get the engine warning light, scan the gauges to verify you do not have high temps or low oil pressure and when safe verify the coolant level is above the sensor.

If you are OK then the sensor needs to be replaced. I am now going to order and keep on hand in the bus one of each sensor relating to these three codes. It will save a service call or more importantly having the coach sit somewhere overnight while waiting for service or parts.

Of the three, the most common sensor failure I have heard about is coolant level, followed by the oil pressure sensor.

Jon, any chance you have the part numbers for the sensors? Have you checked prices at different sources or just going to call Prevost parts. Also, the location of each sensor would be good to know.

Ted,

I am going to visit my local DD dealer and get part numbers and specific information about exchanging sensors.

I will write an article because this is not just a simple swap. If you remove the coolant sensor for example you are getting a hot anti-freeze bath. I want the professionals to give me tips along with part numbers for the different engines and costs.

Jon,Can you ask if the part numbers for the series 60-V are the same as the others?Jack

Jon,

Don't know if this applies here, but I once had a sensor failure on an Aqua Hot unit and the factory talked me through a simple by-pass of the sensor, which got me through until a replacement sensor could be available. This was also a low coolant level sensor, which had failed.

So, is there a way to by-pass any of these critical sensors, once you have positively determined that the sensor is at fault and that the critical condition does not actually exist, until a replacement can be obtained?

If this is possible, it might come in handy some day... or does the potential for a by-pass to be ignored for too long pose a greater risk?

If my local DD guys will tolerate me I intend to dig all the poop up on sensors. I think that the vintage of DDEC influences some of the sensors so I will try to get the variables documented.

I got partway into this a while back and for some reason did not go further, but as I recall about $300 to $400 is the cost for spare sensors. If there is a way to bypass a sensor I will find that out because there is no sense buying a spare if temporary repairs can be made.

Jon,

you can save the cost of a spare low coolant sensor - just keep a paper clip handy to jump the terminals and some electrical tape to hold the clip in place until you can get to a service / parts provider.

Jon,

You may remember I had an oil pressure sensor changed in Knoxville shorly after POG III. It cost about $90.00 at that time and one hour of labor. The guys at Covington took good care of me.

Ken

There is a theory that the low coolant level sensor can be bypassed. That in fact may be the case, but before anybody accepts that as the gospel I will check further.

Some DDEC models measure resistance and just jumping across two wires may not provide the correct value.

So for now lets see if we can verify some of this.

I just received the following for my 01 XLII, I now feel confidant that I will never need them.

TPS part # 531402, $166.10
Oil sending unit part # 561095, $29.43
Coolant level sending unit part # 562396, $27.71

But if I do, I just hope I remember the hiding spot I stash them in!