DDEC frustration

[ArtGill]

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.

Art

[edroelle]

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

[luvrbus]

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  

[Iceni John]

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     

[luvrbus]

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

[Iceni John]

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?

John

[blue_goose]

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.
Jack

[luvrbus]

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

[NJT5047]

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. 
JR

[NJT5047]

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!
JR

[Iceni John]

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   

[luvrbus]

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

[NJT5047]

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

[Zeroclearance]

Clifford,  I have a DDEC Multilink p/n 23528022    My question is..   Is it a decent tool for the early DDEC 1 thru 4?

[Iceni John]

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