Love my Bus but...

[Ken]

Ace, could there be a safety switch on the battery box. You did say that the engine started to cough and stumble when you slid the battery box out while the engine was running.  I'm wondering if Prevost has a safety device to shut the engine down should the battery box become insecure while the coach is in motion.  To stop the engine the DDEC cuts the fuel.

You have to "think" like the computer.

If there is try this. First rectify the reason the DDEC was trying to shut the engine down. In this case you have already done this by fully closing the battery box. Next cancel the signal to the computer to cut the fuel back. Simply switch the dash master control to off for a minute and then to on this resets/reboots the computer. Then to send a new signal to the computer give me fuel, press on the throttle as you crank the engine. Often you have to crank for several seconds [10-15] to get the engine running. This goes against what most of us were taught about starting fuel injected engines where you don't press on the throttle to start. On a computer controlled engine you sometimes have to press on the throttle to start.

The computer should normally allow the engine to start and idle. I have found hundreds of times if the DDEC has shut the engine down for whatever reason, usually due to a signal from a sensor this procedure will often bring them back.

Always carry extra coolant and oil, a DDEC will shut down if the sensors are uncovered and will not restart untill the problem is fixed. Nothing like being stranded on the side of the road when just a little oil or coolant would have you going again. Unlike a mechanical engine where you can unhook a faulty sensor [as long as you know the engine doesn't have a real problem] and the engine will run.

Good luck, I hope this helps, if not with this problem then down the road. Regards, Ken.

[Blacksheep]

Ken, re: the battery tray? This is not something that has happened since I have had it in my posession. This happened when we wentb to look at the bus pre purchase and I haven't forgotten it!
Ace

[garhawk]

hi ace

know very little about the ecm and electronics associated with them.

one 'out of the box' thought.  is your engine breathing.  if catalytic converter is clogged, engine won't start, no matter fuel, air or, ... 

to check, hang a plastic bag over exhaust and give engine a crank.  if bag doesn't immediately blow horizontal, it's a breath problem.

best
gary t'berry

[Blacksheep]

Ok you electronic guru's, here's something else to ponder over and give me your opinion.

This all started with a low voltage problem. I installed 4 new group 31 batteries and still no charging. I was told by Sammy to check the R3 relay and when I changed that, all charging was normal. Now my question is this. Could the ecm recognize TOO MUCH voltage and shut the idle down or work to where it won't overcharge?
I know I'm guessing but that's what happens when you try and figure out something on your own while it rains and spoils your plans!
Give me some input on this thought! I don't think the problem lies in the battery tray and not sure yet until I install a fuel pressure gauge on the 2ndary filter. From what I've learned, anything OVER 15 lbs shows a problem, maybe in the return line! Anything between 10-15 is ok and anything under 10 is obvious.
Ace

[Busted Knuckle]

Ace one other thought just came to mind. I know that since you know your coach that the "cause" is not your problem, but the cure may be the cure.
I once had a know it all driver, who always caused me grief because he "knew it all." Well once he was driving a DDEC controlled bus down the parkway and hit the eng. diagnostic switch instead of the defroster. And the bus immediately lost power and would not accelerate, nothing at all! SO at 4 AM in the morning I get this call from him frantically screaming "we gotta get a bus out here right away this one won't run at all"
Well I finally got him to calm down and listen to me. So I asked all the usual questions and finally got him to admit to hitting the diag. switch.
Well not really knowing what to do my self I told him to go back and cut the power to the bus off for 2 minutes, he insisted it wasn't going to do any good he'd already tried turning the key off and leaving it off at least that long, and he'd shut the pwr off and turned it back on and nothing had changed.
Well I insisted he "try it my way, just to humor me!" Well he did and I had to listen to him bitching the whole time! Then at the end of 2 minutes (truthfully 30 seconds probably would have done it), I told him to turn the power back on, and go back up front. Once he was back in the driver seat I told him "turn the key on, and watch the lights, and tell me what happens."
Well he watched and told me that the lights did just like they always do at start up. So I asked "so you have no warning lights or shut down lights on right now?" And he told me that was correct. I told him to start it and see what happened, and as he was telling me he did not "understand what difference turning the power off made" I heard the engine revving up and the passangers cheering. So I hung up on him! He called me right back and asked why I hung up on him, and I told him "because I didn't understand why having power on the phone was helping me sleep!"    BK  

So what I am saying is try turning off all power then turn it on and see if it has reset itself! HTH

[luvrbus]

Ace, I don't know much about relays and the Prevost system but on my H-41 on the way from Texas we had a charging problem and the guys in Ft Worth told us what relay to replace and we were told never use a suppressor diode type what that means I have no idea maybe some of the guys here can answer it      good luck

[Nick Badame Refrig/ACC]

Hi Ace,

Juist a stab in the wind....


Prevost Car Inc.

Models: Prevost H3-41 Years: 1994-1998 
Prevost H3-45 Years: 1994-1998 

Number Involved: 1,784
Dates of Manufacture:May 1994 - June 1998
NHTSA Recall No.: 98V172
Vehicle Description:
Description of Defect:The alternator and battery cables were not properly installed. This condition can cause the nuts to loosen over a period of time, causing a short circuit and possible fire hazard.
Remedy: Dealers will inspect, remove, and re-install the alternator and battery cables.
Owner Notification: Owner notification began July 16, 1998. Owners who do not receive the free remedy within a reasonable time should contact Prevost at 1-418-883-3391.

Good Luck
Nick-

[Blacksheep]

Nick yes I'm aware of that recall. We got the notice but really think the problem lies a different place. We have checked all the cables and connections and all are fine but we do plan on having Prevost J-ville having a look over IF we can ever get it running and stay running!
Ace

[blue_goose]

Ace
Read my post again, get volt meter and check those voltages and see if they are there.  If they are you must not be getting fuel.
Jack

[NJT 5573]

Ace,

How did you prime the system after you changed the filters? Prime pump? DDEC is damn near impossible to re-prime. The book is pretty specific and if your diagnostic lites are going out with no codes, this is what it says.

(1) miscalibrated Throttle Sensor
(2) plugged fuel filters (or lost prime)
(3) hose not connected to turbo boost sensor
(4) proper gapping of Timing Reference and Synchronous Reference Sensors
(5) diagnostic request ckt #451 is shorting to ground
(6) loose battery power ckt #  240 or # 241, ignition wire ckt # 439 or ground ckt # 150 wires
(7) check pulley pulse wheel, missing teeth, dented, or loose
( check for signs of insulation wear on injector harnesses
(9) check power contribution from each cylinder using cut out feature described in DDR instruction manual  

You can also check #9 with an infared temp gun by just reading each cylinder at the exhaust manifold. I have used my hand also. Cold ones don't pass.

I could not get my DDEC 2 to reprime because the sensor by the fuel filters would not allow the DDEC to open the throttle. I pulled that wire off and DDEC would then allow the injectors to open and pull the air through the system. Once the air was cleared I replaced the wire and I have not opened the fuel system since. That sensor is located at the top of the secondary filter and you need a screwdriver to remove the wire.

I am still confused about your run situation. Will the engine run for extended time but at 300 RPM, or does it run a little and then die?

[Blacksheep]

Back home now and getting ready to install a fuel pressure gauge at the secondary filter to see if anything there leads me down a particular path.

As for changing the filters? I don't see why or how this has anything to do with the problem as the problem occurred before the changing! Changing the filters was my first step in trying to fix the problem.

Now before I install the pressure gauge, I am thinking about disconnecting  the batteries for a few minutes and give the ecm a hard boot so to speak! Turning the batteries off doesn't eliminate power to the ecm. It always has power as long as the batteries are hooked to it! I just know when my blackberry gave me problems, the tech people told me to remove the battery and wait a few minutes then re-install the battery and the problem usually fixed itself! Maybe this works the same way! Remember, I DID just install the 4 new batteries and maybe there was a reason a glitch occurred during that time!

Whatever it is, I am beginning to think that it isn't something very major. Probably something really stupid! The good thing is, I AM learning from all this! 

Ace

[Tom Y]

Ace, Are you also going to pull the fuses to the DDEC for a couple minutes? Are there 2 10 amp fuses? Good Luck  Tom Y

[Nick Badame Refrig/ACC]

Back home now and getting ready to install a fuel pressure gauge at the secondary filter to see if anything there leads me down a particular path.

As for changing the filters? I don't see why or how this has anything to do with the problem as the problem occurred before the changing! Changing the filters was my first step in trying to fix the problem.

Now before I install the pressure gauge, I am thinking about disconnecting  the batteries for a few minutes and give the ecm a hard boot so to speak! Turning the batteries off doesn't eliminate power to the ecm. It always has power as long as the batteries are hooked to it! I just know when my blackberry gave me problems, the tech people told me to remove the battery and wait a few minutes then re-install the battery and the problem usually fixed itself! Maybe this works the same way! Remember, I DID just install the 4 new batteries and maybe there was a reason a glitch occurred during that time!

Whatever it is, I am beginning to think that it isn't something very major. Probably something really stupid! The good thing is, I AM learning from all this! 

Ace

You never know...  My dad had a fuel line collaps in his 4104 and had the same symptoms as you. He ended up
replacing all the lines.

Good Luck
Nick-

[JohnEd]

Ace,

Glad to hear you eliminated the bat box as the problem.  Another cause eliminated.  Onward and upward.  The reason I went there in the first place was your experience when you were in the process of purchase.  But, also, you mentioned that the night before the problem you had pulled the tray out half way......and something about pizza.  Sounded like you might have gone Freudian and spoke your problem.

You aren't the only one learning.....be assured of that.

John

[Blacksheep]

OK guys, here is where we stand (at the moment)!

Now were thinking it's ot a fuel problem at all and were leaning back towards it being electronic as in a cooked ECM! Why?

Let's look at the whole picture from the start!

Coming home from Arcadia....low voltage light comes on
Bus starts shifting irratic ... due to low voltage
Installed 4 NEW batteries..... not charging at all
Sammy request looking at R3 relay
Changed relay
BOTH 12v and 24v Dash gauges pegged
Checked regulator and found it to be maxed out on adjustment
Lowered the adjustment and although charging problem fixed the problem with idling and acceleration started
Changed fuel filters and seemed ok at the time but it was late
Next Day, and up until now same problem exist

Sooo, with all that, everything still leads toward the electronic side and after talking to a few more knowledgeable people today, we all think that since it started with a no charge situation, and then fixing a bad relay which in turn fixed the charging problem BUT the prior owner/s had already tried to fix the same non charging problem by turning UP the adjustment on the regulator to full max unbeknown to me.
Bottom line is, When I changed the field relay, then turned the key to start the bus, an abundant amount of voltage was fed to the ECM and possibly smoking something inside it to create the problems I now have although the ECM shows 13.4 volts as engine runs and 12.8 with it off, some damage may have been donw from the added surge of voltage.

Only other hopeful thought is IF there is any type of safety link or fuse or surge protector between the regulator and the ECM. Looks like another call to Prevost to find out unless of course someone here knows.  

Ahh the joys of owning an electronic bus!

Ace