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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: Iceni John on July 05, 2012, 07:58:42 PM

Title: DDEC frustration
Post by: Iceni John on July 05, 2012, 07:58:42 PM
During my desert trip a month ago the CEL and SEL both came on;  I immediately pulled over, checked the coolant level and temp and oil pressure and found them all OK.   The engine did not shut down, so I cautiously continued the last few miles.   Two days later the engine started OK, but the CEL and SEL came on several times on the drive back home, again without the engine shutting down.   I read six codes from the CELís flashes:
12  -  Power Take-Off Speed Adjust high voltage,
36  -  Oil Pressure Sensor low voltage,
41  -  Timing Reference Sensor pulses fault
44  -  Oil or Coolant Over-Temperature
45  -  Low Oil Pressure
46  -  Low Battery Voltage

Last Saturday I started up the bus to top up the tank (dieselís dropped to $3.79 here!), but after about two minutes idling while building air the engine shut itself down with the CEL and SEL both on.   When I tried to restart, neither the CEL or SEL would illuminate at all for the few seconds before they normally go off, and the engine would spin but not fire.   Again I checked the vital signs  -  both batteries were about 12.8 volts, there was good oil pressure, and plenty of coolant in the expansion tank, in other words no obvious reason for a shutdown.

A few nights later I tried to start again;  for the first few tries the CEL and SEL did not come on at all and the engine turned but did not fire, but then they finally came on as they should and the engine fired right up.   However, after a minute the engine shut itself down again with both lights on.   This evening the engine fired right up, but both lights came on after a few seconds so I shut it down.   The same six codes are still flashing out on the CEL.

Iíve been reading through my DDEC II Troubleshooting Guide to try to understand whatís happening, but the more I read the more confused I get.   I donít think I have a PTO, so Code 12 is a mystery to me.   This evening I measured the voltage at the Oil Pressure Sensor and got 5.06 V there, right in the middle of the desired 4 to 6 V range, so shouldnít that eliminate Code 36 as a reason for the shutdowns?   I have no way to check Code 41  -  maybe thatís the culprit?   The oil and coolant temperatures and oil pressure all seem to be OK, so shouldnít that eliminate Codes 44 and 45 as possible reasons?   My starting batteries are both healthy, and the DDEC fuses are getting about 12.7 V, so why Code 46?   Unfortunately I donít have a DDR, so I donít know how many of these six codes are historical and how many are active and triggering the shutdowns now.   (Too bad DDEC II doesnít show active codes on the SEL and historical codes on the CEL, like later DDECs do.)   

One thing I changed when I relocated my starting batteries last year was to have the three DDEC fuses now wired after the main battery disconnect switch, not directly connected to one of the batteries as before.   I did this to avoid the battery the DDEC was connected to from always draining down, and since making this change that battery has always held its voltage without a problem.   Could having the DDEC now connected this way have possibly damaged the ECM?   What exactly is the reason for DDEC to be directly connected to the batteries?   And yes, these three fuses are OK, and the four DDEC cube relays in the busís main JB also seem OK  -  if these werenít, the engine wouldnít start?

Iíve also cleaned all the connections and grounds for any sensors I could find, such as low coolant and coolant temp.   I donít think this is a likely cause of my problem, because my bus has absolutely no corrosion and has always been in dry CA  -  I havenít found any poor connections anywhere so far.

So, do any of the resident gurus and cognoscenti here have any ideas to save me further anguish?   If I have ABC Bus look into things, Iíll be spending more than I paid for the whole damn bus.   Iíve said it before, and Iíll say it again now  -  I wish I had a nice simple MUI engine.   Fuel, air, compression  -  thatís all I need in a diesel.

John, feeling VERY exasperated

Title: Re: DDEC frustration
Post by: Ed Hackenbruch on July 05, 2012, 09:32:11 PM
John, i have a nice simple MUI engine so i don't know anything about the  DDEC engines. ;D  Did you try disconnecting the battery cables for a few minutes to see if that will clear/reset it?

Title: Re: DDEC frustration
Post by: luvrbus on July 05, 2012, 10:00:40 PM
Isn't 46 low backup battery voltage you probably get that from not having the ECM hooked to the batteries the DDEC1 is the only DDEC you can reset by disconnecting the batteries could be you need a new backup battery now.

I would hook it back direct to the batteries and see also I have been told the 3 main grounds on the ECM need to be on a common ground terminal

good luck

Title: Re: DDEC frustration
Post by: Iceni John on July 05, 2012, 10:47:08 PM
My book says that 46 is "Engine running with low battery voltage (less than 10 volts) for more than 30 seconds".   I assumed that meant the starting batteries which are healthy, but maybe I'm wrong.   Does DDEC II have an internal battery in the ECM to save the codes, or are they saved by some non-volatile memory that doesn't need a constant voltage input?   When I bought the bus it had been sitting for a few months without any batteries at all, and when we connected one Group 31 it fired right up with only a whiff of ether.   This makes me think that the ECM doesn't need a constant voltage to preserve its functionality, but maybe it does?   After reading old postings here about related problems, some folk seem to be running their ECMs after their main battery disconnects, but there must be a good reason for Detroit to specify running the ECM straight off the battery.   Perhaps I've been too hasty in changing it.   Luvrbus, I'll take your advice and rewire the three DDEC fuses to how they originally were off one battery, even if I have to occasionally charge that battery to keep it from going down.   I'll also make sure all the DDEC grounds are to one place  -  I think they are now, but I'll check.   I still hope I haven't damaged the ECM by what I did.

I won't have time until next week to do more diagnosing, but I'll switch the batteries back on tomorrow morning and leave them on.   As far I know I don't have any other phantom loads except for the tachograph (and I can disconnect it, not that I have any cards for it anyway), so maybe keeping the batteries on won't be the problem it was before, especially now that I have a decent charger to top them up.

As usual, Luvrbus has come through with more words of wisdom than I could ever have hoped for.   Thank you  -  you're the best!   I'll post again next week when I've had some more time to get my hands dirty.   I feel slightly less bummed out now.

Thanks, John

Title: Re: DDEC frustration
Post by: Sam 4106 on July 06, 2012, 01:00:01 AM
Hi John,

I think luvrbus has solved your problem. When I was having the same situation, crank but no start, a good mechanic told me that the ECM has to have power all the time. My problem was that whoever installed the wiring for my engine had installed a solenoid in the circuit that was only powered when the dash switch was on, 8V92TA DDEC II transplant into a MCI8. The solution was to eliminate the solenoid so the ECM was powered all the time. The engine has started every time since the solenoid was removed. Our bus sits in my shop all winter with only an occasional battery charge without going dead. I think by disconnecting the tachograph you will eliminate the problem of the batteries going down. By the way how do you get the codes to flash? I don't have a manual for my engine so I don't know how to flash the codes. Thanks.

Good luck, Sam

Title: Re: DDEC frustration
Post by: belfert on July 06, 2012, 04:53:06 AM
My bus has the DDEC set up from the factory to get voltage all the time even with disconnect turned off.  My batteries will go flat in a week or two if I don't keep a battery tender on them all the time.  I have a Vanner equalizer so just one battery isn't taking all the drain from the DDEC.

Title: Re: DDEC frustration
Post by: buswarrior on July 06, 2012, 05:05:08 AM
Fix code 46 and watch the rest disappear?

I only know enough to be ignorant.

My money is that all those other codes would be thrown by the same conditions that threw the code 46.

Clean and check grounds.

How old are your batteries? What happens to voltage at the ECM before, during and after a start?

Did someone mention grounds?

I'll mention it again.


Start there, ignore the others until you make 46 go away.

happy coaching!
happy coaching!

Title: Re: DDEC frustration
Post by: robertglines1 on July 06, 2012, 07:04:20 AM
Have batteries load tested indivually.  was a ghost that got me several years ago.  showed good on meter but on fell on face under load.  Prob not your problem but keep in mind.   Bob.

Title: Re: DDEC frustration
Post by: Iceni John on July 06, 2012, 08:23:51 AM
By the way how do you get the codes to flash? I don't have a manual for my engine so I don't know how to flash the codes. Thanks.
Crown put a momentary switch next to the DDEC OverRide switch which makes the CEL flash out the codes in numerical order.   Easy!   I wish I had the DDR code reader, then I would be able to erase all the historical codes and see what the active ones are.   For all I know, the present fault could be the same code over and over again, or it could be different codes each time  -  without the DDR I don't know.

I just turned the batteries on, and I'll leave them on until I have time to play with things next week.   I'll definitely be restoring my DDEC to constant power next week, as that's what the collective wisdom here suggests.

I'll report back next week with the results.   Can you believe this problem happened on the same day I finally got my toilet working?   After three years of back-breaking grunt work installing the four tanks, making a water-distribution center, relocating the starting batteries with new slide-mounts, making a generator slide-mount, making a spare tire mount under the front, all this to have a working loo, then that same day the darned bus decides to not start.   Life's not fair!   Anyway, to try and forget these woes, I'm off to Yosemite tomorrow to hike up to Half Dome  -  a non-electronic weekend sounds attractive at this point.

Thanks, John     

Title: Re: DDEC frustration
Post by: RJ on July 06, 2012, 08:36:54 AM
Anyway, to try and forget these woes, I'm off to Yosemite tomorrow to hike up to Half Dome. . .

John -

If you are coming/going into/out of Yosemite on Hiway 41, I'm just an hour S of the Park in Fresno.  If you've got some time, give me a call, I'll buy the Pepsi!  Five 5 nine, 2 six zero, four one zero 6 will get thru to my cell.


Title: Re: DDEC frustration
Post by: Ed Hackenbruch on July 06, 2012, 08:42:41 AM
See? i told you i didn't know anything about them!!!! ;)

Title: Re: DDEC frustration
Post by: jimsflx on July 06, 2012, 09:10:10 AM
john,my mci with ddec 2 will run down the batterys in a week or so. so i ran a cutoff switch to the ecm ground to cut power to it. if it did not have13.1v from the batterys it would turn but not start after a week or so. a shot of either and it would fire up .goodluck jim

Title: Re: DDEC frustration
Post by: Iceni John on July 06, 2012, 12:28:10 PM
john,my mci with ddec 2 will run down the batterys in a week or so. so i ran a cutoff switch to the ecm ground to cut power to it. if it did not have13.1v from the batterys it would turn but not start after a week or so. a shot of either and it would fire up .goodluck jim
Interesting.   I heard that DDEC only draws a few milliamps when it's not actually working, such as when the engine is off, so two big 8D batteries shouldn't be running down so quickly just from the ECM's standby load, should they?   Maybe you had another phantom load, unknown to you, that was quietly sucking your batteries dry.

As I mentioned, my bus is starting fine (at least, when the DDEC isn't playing possum) with less than your 13.1 V at the batteries, but I was still having both lights come on while driving, when the alternator is producing about 13.7 V.   Mind you, even though the lights were briefly coming on while driving, the engine wasn't shutting down (thank goodness).

Ether isn't going to help start the engine, even though it will do so for a few seconds.   The issue is that the ECM is either not coming on at all, or it's shutting down, and without the ECM working the injectors won't inject.

I'll see if keeping constant power on the DDEC changes anything.   I'm worried I may have done some harm to the ECM by depriving it of its electrons.   Luvrbus suggested there may be an internal battery inside the ECM that could have run down  -  definitely plausible, but there's no mention of such an internal power source in any of my DDEC literature and manuals.   Perhaps I need to call the local DD folk and pick their brains about this.

On a sort-of related subject, as I was walking past the local fire station last night one of their ladder trucks set off down the road with its lights and sirens on.   It sounded like a 8V92  -  I think I'll ask them who services it.   Maybe that would be another possible resource to help solve my problem?

Thanks guys, you're the best

Title: Re: DDEC frustration
Post by: luvrbus on July 06, 2012, 01:34:43 PM
John, can you get the serial number from the ECM and do you have any idea what version of software you have ,the Pro/Link should  give you that information

good luck

Title: Re: DDEC frustration
Post by: Iceni John on July 06, 2012, 03:36:41 PM
How/where do I find the ECM's serial number?   I have no idea what software version it has!   I'll try and look next week when I have some time.

Maybe I need to bite the bullet and buy a reader.   Is the Detroit DDR the same as a Pro Link?   Don't earlier DDECs like mine use a proprietary software protocol that regular readers can't interpret correctly?

At this point I really need to clear out all the historical codes, then I'll have a better idea what's happening now.

Thanks, John

Title: Re: DDEC frustration
Post by: ArtGill on July 07, 2012, 05:36:46 AM
Have you done and welding on your coach recently?

My DDEC got flake after a little welding without disconnecting my batteries and DDEC. I ended up replacing it with a rebuilt and solved all my strange little problems.  Like shutting down at a stoplight and having to recycle my battery switch to restart.  Just a suggestion.


Title: Re: DDEC frustration
Post by: edroelle on July 08, 2012, 07:42:44 AM
I had similar problems with a DDEC III - many codes set for unexplained reasons.   I removed ECM connectors and sprayed with contact cleaner and added a SMALL amount of dielectric grease.   Problem was eliminated.

I second Buswarrior's comment - Check Grounds.

You might also purchase a SilverLeaf (was about $400.) and log information with a laptop.   I found I was getting codes set in 1/10 of a second.    This led me to an electrical connection problem rather than something more serious.   You could log voltage and find out what the ECM is seeing.

Ed Roelle
Flint, MI

Title: Re: DDEC frustration
Post by: luvrbus on July 08, 2012, 09:34:04 AM
46 is his problem James and I got his DDEC 11 to give the same codes on a Pro/Link (203) by using a 9v battery for power,one problem you will always have is DD switched manufactures about 1/2 through on the run of the DDEC 11 makes it interesting sometimes

James gets a little paranoid when he reads about problems with DDEC 11 so he starts looking every time a post is made about a DDEC 11 lol  

Title: Re: DDEC frustration
Post by: Iceni John on July 11, 2012, 09:03:53 PM
OK, good news, I hope.

After connecting the DDEC directly to the batteries last week, I started the bus tonight  -  key to Start, all lights came on for a few seconds (that's better than before), then they went out except for the CEL (that's not so good).    The engine started up perfectly, and after 30 seconds I blipped the throttle up a few hundred RPMs and the CEL went out.   Yeah!   It idled just fine for ten minutes or so:  no CEL or SEL came on, it didn't shut down by itself, and I briefly ran it up to 1800 RPM without any issues.   Methinks it may be OK now.

I've now reconnected the DDEC directly to battery no.1, so when I turn the master switch off only the DDEC is still live.   That's how Detroit wanted it.   I guess that the ECM doesn't like losing power for long periods of time.   I'll just have to charge that battery every now and then, a small price to pay for not screwing up the DDEC.

I still need to clear the codes, then I'll have a better idea what's still happening now.   Maybe ABC Bus down the road can clear them for me.   I'll look into buying a DDR or whatever else can clear earlier DDECs like mine.

Oh yes, Yosemite was as beautiful as ever, and the Half Dome hike was wonderful.   Nothing like a short walk in the park to clear one's head.   We met R.J.Long in Fresno and happily talked buses over lunch, then on the way back we stopped by a fellow Crown Coach Junkie in Mojave to see his seven buses.   Just under four hours from Bishop to Montebello  - US 395 might be the best road in CA.   Fun!

John, keeping fingers etc well crossed for now     

Title: Re: DDEC frustration
Post by: luvrbus on July 12, 2012, 07:20:57 AM
John, if you get close to Albuquerque I have a friend there that has a Kent/Moore reader for the older DDEC engines that is why I was asking for the serial number my Pro/link will read the later 11 and I use a OBD reader for the older  models

good luck

Title: Re: DDEC frustration
Post by: Iceni John on July 12, 2012, 08:01:19 AM
Thanks for the kind offer  -  however, I don't think Albuquerque is in my future at this point!
I had a good look at the ECM last night, but I could not find a serial number on it.   Does it have to be unbolted to find it, or is it under the top heat shield?


Title: Re: DDEC frustration
Post by: blue_goose on July 12, 2012, 11:38:26 AM
There isn't much you can read on the DD11.  You can clear the codes and not much more.  Any prolink with the 11 reader or the Detroit program can clear the codes.

Title: C
Post by: luvrbus on July 12, 2012, 07:55:51 PM
John, you can do wonders with a Kent/Moore J36500 DDR they only made 1000 and dealers were the only places that had the Kent/Moore J36500 they were not sold to the public

I am always chasing 1 but always late it is gone before I can buy it so keep your eyes open if you are going to own a DDEC1 or 11

Title: Re: DDEC frustration
Post by: NJT5047 on July 14, 2012, 09:45:24 PM
After reading thru once, I may have missed something, but when you moved the DDEC B+ to the battery master, that is a 24v feed.  The DDEC is 12v only.  A DDEC and ATEC unit should always have 12v on the B+ leads.  However, a DDEC II will keep codes and program when disconnected...unlike a DDEC I, which dumps set codes whenever the battery voltage is removed.
The 12v supply was the reason for connecting the DDEC to the center battery tap.  That is 12v.
If the supply voltage is correct, you likely have a wiring or ECM problem.  If you look at a wiring diagram for your DDEC you'll see that the sensor voltage (about 5v) feeds multiple senders and sensors.   Check the related harness leads and all grounds...especially the remotes such as coolant tank sensors.  You have several shutdown codes that are unlikely to represent actual failures.
A DDEC I doesn't require a reader.  Nothing you can do.  But a ProLink is useful on a DDEC II.  DDEC II, III, AND IV are later designs and store a lot of data.   
DDEC I was limited to '87 "clean air" coaches. 

Title: Re: DDEC frustration
Post by: NJT5047 on July 14, 2012, 10:31:18 PM
Thinking a bit more about the CEL being intermittant.   The CEL is "on" whenever the Ig master is on.  If the CEL fails to light, that would seem to be a B+, Ig switched power, or ECM plugs or harness.   The CEL is grounded by the ECM.  You need a pinout for the ECM so that you can verify why the CEL fails at times.  That could also be corrosion in the DDEC fuse cases too.  Or ECM dedicated grounds.   I'd for sure check all DDEC harness plugs. 
Also, your Crown is 12v?  Hope so.    Hooking to a 12v master ain't ideal, but won't harm anything.   Hooking to a 24v source clearly would be problematic.
Still, having a working potty and cold fridge is better than a running diesel while fuel is bumping $4 bucks!

Title: Re: DDEC frustration
Post by: Iceni John on July 15, 2012, 09:53:43 AM
JR, thanks for your replies.  My bus is 12 V throughout  -  the only 24 V Crowns were the tour buses and the Atomics.   Every connection I've checked so far has been clean and tight, so I'm thinking they're probably not causing the codes.

After hours of Googling it's still not clear to me what, if any, backup battery is inside a DDEC II ECM.   One post on another forum said it's a carbon-pile battery, but that doesn't make sense to me;  it did say however that a replacement Sony lithium battery could be soldered in.   That's more than I could do!   A post on BCM showed pictures of the inside of a DDEC II ECM, but no battery was obviously visible there.   At this point I'm stabbing in the dark without knowing what codes were thrown when and why.   I'll talk to ABC Bus this week to see if they can clear them, and only then will I know what's still happening.

Thanks, John   

Title: Re: DDEC frustration
Post by: luvrbus on July 15, 2012, 10:05:42 AM
There were 2 different manufacture of the DDEC 11 and till you have someone with a reader to pull up the serial number and software version you are in the dark but the Kent/Moore will read both models along with the DDEC 1 you should be able to clear the codes with a OBD reader I do all the time

Title: Re: DDEC frustration
Post by: NJT5047 on July 15, 2012, 10:08:58 PM
The engine will start and run irrespective of stored codes.  But if the fault is seen as continuing,  the engine will shut down, if a shut down fault exists.  Water temp, low water level, oil over temp, all are shutdown faults. 

 The PTO code on your coach is related the TPS.  The ECM sees them as the same.   Low or high voltage, injection pulse width, and PTO codes are not shutdown codes.  However, PTO codes will cause driveability issues.
You've got wiring problems....very likely. 
Your ECM is mounted on the engine?    DDEC II, III, and later are engine mounted.  DDEC I is mounted in the body somewhere.   
Before you do anything to the  ECM, pull it off and let a DD shop test it. They can verify whether it's working or not.
Those units can be exchanged and repaired.  But most won't deal with it if you open it up.  I'd be really surprised if the ECM has failed.  While DDEC systems can be a headache, the problems are rarely due to ECM failure.  The interface between the coach and DDEC harness is a common problem. 
If you don't have DDEC II diagnostic guide, it's unlikely that you will sort it out.  If you have such a guide, do pinouts for Ig, B+, grounds, and TPS.   The guide is very staightforword. 
Somewhere in the front of your coach is a box where the DDEC harness interfaces with the coach electrics.  That should be checked as well.   Those faults related to the engine are not logical. The fact that the CEL and SEL intermitant is a sign of electrical issues,  whatever powers up the CEL, probably powers up the ECM IG circuit.  Maybe.    Are you sure that you have a DDEC II?   If you go to coachinfo.com they have pics of the various DDEC ECMs.  They also sell the diag guides...or did?   I've been off doing other things and haven't kept up.   
Sorry about the crap typing,  Android isn't quite ready for major BB posts.  Got Tapatalk, but haven't tried it yet.
Good luck with your electrics!   JR

Title: Re: DDEC frustration
Post by: Zeroclearance on July 15, 2012, 11:13:02 PM
Clifford,  I have a DDEC Multilink p/n 23528022    My question is..   Is it a decent tool for the early DDEC 1 thru 4?

Title: Re: DDEC frustration
Post by: Iceni John on July 15, 2012, 11:31:06 PM
JR, yes, it's a DDEC II (the fuel-cooled one), and I do have the DDEC II Troubleshooting Manual.   I did some pinout testing, but I'll do some more if I can.   In the bus's main JB are four cube relays for DDEC and a small mystery box for the coolant level sensor  -  the relays are all OK, but I haven't tested the coolant thingy.   The connection to the coolant level sensor itself was iffy, so I replaced its wiring last week.

I'll start up the engine tomorrow and see how long it runs, hopefully without it shutting down.   If I can get 30 minutes at fast idle without a shutdown or any lights, I'll drive the bus to a DD dealer to get the codes cleared.   Maybe I should first just trundle around the RV yard a few times  -  if it's going to shutdown on me, better there than out on the road.

If only there were a way to easily un-DDEC it and go back to simple MUI, I'd have done it long ago!   Anyone here want to swap engines with me?   (Yeah, dream on . . .)

Thanks, John

Title: Re: DDEC frustration
Post by: Ace on July 16, 2012, 04:40:27 AM
John where are you located? I have a prolink that i can erase the codes for you!

Sent from my iPhone using Tapatalk

Title: Re: DDEC frustration
Post by: usbusin on July 16, 2012, 06:51:10 AM
John where are you located?

Behind the Orange Curtain, SoCal.

Title: Re: DDEC frustration
Post by: luvrbus on July 16, 2012, 07:14:17 AM
Clearing the codes is not the problem John is looking for the cause he could find a DD dealer in his area that still has the old DD software unless CARB has ban that also.

Don is in Bakersfield he runs the DDEC 11 and has the toys to play with it or know of somebody in his area that does not much you can do with a pro/link on a DDEC 11 clearing codes is one you can do

Title: Re: DDEC frustration
Post by: Don Fairchild on July 16, 2012, 01:45:48 PM
Clifford I run a DDEC III on my country coach. I did have two DDEC II DDR's until some one we both know left and I have not seen them again.