DDEC Issue again...

[Sebulba]

The procedure to get codes involves a switch on the dash, detailed in MCI materials.

You really, really, need to get a scanner for your electronic bus systems, one that will clear codes. You have both a DDEC III and an WTEC transmission to talk to.

A  busnut is a sitting duck at roadside without a means to read the computers.

You cannot be coached to a repair, without hard information.

The roadside pirates will liberate thousands of your dollars, for something you could have done for yourself.

Happy coaching!
Buswarrior

All makes perfect sense.

I agree about getting a scanner.  There was a recent thread that discussed this.  I still wasn't sure what was the best one to get.  If you have an opinion on that, I'm all ears.

Thanks for chiming in. 

Later post will exain my day...

Seb

[Sebulba]

Maybe Lee has an idea. When you get no lights on the dash use a voltmeter and check the circuit breakers to see if there is voltage on both sides. Failing circuit breaker is a potential problem you might have. No voltage to computer if will never start. You probably have a DDEC III but the DDEC IV is virtually the same. Just a little more upgrades. I have a DDEC III/IV troubleshooting guide (500 double sided pages) which I can get copied if you want to pay for it plus shipping. No idea of the cost. Next time you have lights operate every switch you have to see which one makes the CEL and SEL (red and Yellow lights) flash out any codes. Code 25 is 2 flashes and a pause then 5 flashes. 25 means all is okay. You have to have a switch (momentary type) that will make the lights flash. You can call me if you want at 905 873 8929  Bill.

Hello Bill,

Thanks for your insightful post.

Yes, LuvrBus mentioned that troubleshooting guide. This morning I use it and got going.  Didn't actually find anything wrong, but in the process of working through the troubleshooting procedure I took wires off of the battery, the ground wiggled and was not tight.  I wire brushed them all and cleaned the up and reatache, both + and -.  Next it wanted me to check the fuses.  I pulled them, that looked fine but I did a continuity test and the are ok, I cleaned tirminals and put together.  After every step I turned on the Main switch, up to this point no change, but still good to clean them up.  The next step in the guide was to pull the top right plug of the DDEC, the one with 5 terminals and check voltage on 2 terminals.  It tested fine, but this time when I hit the switch, I hade lights and barked off.

Since we were running, we left and came to Santa Fe without shutting down, 447 miles. After we got parked and ok I shut down and 15 minutes later it started again.

Do I have it solved? I don't know, I didn't actually find anything wrong, but I did clean some things up and plug and un plug some things

Time will tell.

As for the switch to get the codes.  I do have a momentary switch that lights all lights on the dash, I assumed to tell if the bulbed are all functioning. Maybe that is the one to get the codes?  I guess, I hold that down and watch for the flashes?

We'll that was an interesting few days. 

We are here for a few days and then need to go the Albuquerque.  I will probably check tomorrow and see if we can start.  And go from there.

Thanks for the help

Seb

[Sebulba]

95% of problems with a DDEC is always on the OEM side the Detroit side of the ECM is usually good or bad,when people start cutting wires and removing OEM add on without delating those from the ECM you have problems.A Prolink will delete a few if they were preprogramed which most are not,your problem could be simple like the kneeling option and a scanner will not flash a code for OEM equipment.I have a stack of trouble shooting manuals for the DDEC and all I ever use is a blow up schematic of the Detroit responsibility  and the OEM responsibility, when the wiring leaves the ECM it is a OEM issue like a chassis computer if you have one on D3     

Hmmm.... Clear as mud, well, maybe a little clearer. 

OEM, kneeling function, ok, whel chair lift?

I had one, it is removed now, although I did it very carefully and that was 8 months and many miles ago.

This problem has, for the most part, been with me since the 4th day we owned it about a year ago.  The only change is that what happened in the past was that the DDEC would not light, but I could still start.  Now the Red and Yellow light fail to light and cannot start.

Thank you  for you input.

I do appreciate your vast knowledge about these beasts and am doing my best to assimilate all.

Seb

[Sebulba]

From your latest description, You may have an intermittent connection issue with your ignition switch. When it works you have no issues, but when you shut it off, and try and restart it, maybe yes, maybe no. It could be as simple as cycling the switch a few times to get going. That may work a few times for you. Good luck

I agree that it seems to intermittent.  The only discirnable pattern I can see is that it only happens on cold start.  It has never been an issue once on the road, although today I just played it safe and didn't shut down till we got here and won't need to move for a few days.

Ignition switch you mentioned? I assume you mean the main power rocker switch?  I guess I wouldn't be averse to just replace that one with a brand spanking new one.  No telling how many thousand times it had cycled and maybe it's just worn out.  Then it's good for as long as I need it.

Would that be a part to talk to Luke about, or?...

Thanks for your help

Seb

[Sebulba]

When B&B would do a repowers on buses or rewires on a burnt Prevost,when you saw Van with 50 rolls of wire, bags of Deutsh pins and barrels business was picking up lol.Van made it look easy building a harness 3 inches around, I don't have that much patience but when he was finished it would fire off   

Wow, that is cool.  It's great to have knowledgeable and highly skilled people around.  Alot of these skills at dying, unfortunately.

Thanks

Seb

[Sebulba]

Look on the right side of the DDEC unit mounted on the motor. It will have two plugs on the right side. Disconnect the upper plug. It's a bit tricky to get a flat blade in there and release the catch.
It's not the plug with the bolt in the center.

It's the same setup whether you have a DDEC III or DDEC IV.

When you get it loose, look at the wires on the back. Mine is easy, I have red and black. You can trace them into the plug. RED is hot, Black is ground. With the ignition on, check for voltage going to the computer. https://www.google.com/search?q=detroit+12.7+ecm+wiring+diagram&rlz=1C9BKJA_enUS846US847&hl=en-US&sxsrf=ALiCzsbBX9iEDRQNFlhaNJ3z73KqdbMFAg%3A1669162633407&ei=iWZ9Y-msGLafqtsP87WwkAE&oq=ddec+iii+wiring+diagram+pdf&gs_lcp=ChNtb2JpbGUtZ3dzLXdpei1zZXJwEAEYBTIKCAAQRxDWBBCwAzIKCAAQRxDWBBCwAzIKCAAQRxDWBBCwAzIKCAAQRxDWBBCwAzIKCAAQRxDWBBCwAzIKCAAQRxDWBBCwAzIKCAAQRxDWBBCwAzIKCAAQRxDWBBCwA0oECEEYAFAAWABg6ERoAnAAeACAAQCIAQCSAQCYAQDIAQjAAQE&sclient=mobile-gws-wiz-serp#imgrc=Mt_eTPL6s-2shM&imgdii=q92QuMnvCRT6nM

Don't go flying by the basics. When you hear hoof beats, think horses not zebras. The intermittent nature of your problem does not indicate a failing ECM. When the check engine and stop engine lights don't come on, the first place to look is to see if the ECM is actually getting power. By checking at the power supply connection you will start a methodical process of finding the problem.

Now if it's not getting power, you start working backwards through breakers and relays all the way to the ignition.

When you say the DDEC lights up, are you talking about the PRO Driver display? If so, then it will show computer errors if you have them. It will not tell you that you don't have power to the computer, cause obviously the computer is not alive.

Hello Richard, The procedure that I followed in the troubleshooting guide basically mimiced what you mentioned in the first part of you post.  See above post for more details.

Yes, when I say the DDEC doesn't light, I am talking about the Pro Driver display.  Sorry if I was using confusing terminology.  I'm only a year into this beast, and there is aot to learn.

So the Pro Driver display  show errors?  Hmmm.  I've never messed with it.  Will they display automatically, or do I have do something? 

Thanks a million

Seb

[Bill Gerrie]

So you are talking about the Prodriver and not the SEL and CEL red and yellow lights on the bus dash from the main engine computer. The Prodriver is run off the DDL connector where you retrieve codes with a Prolink. It does read codes, keep track of mileage etc but should never stop the engine from starting. When you can't start and no SEL and CEL lights on the dash the main computer isn't getting power. That is the small plug you just had off the engine computer. Sounds like a bad connection there. Clean them well and dieelectric grease. Be carefull not to bend the pins. Remove fuses first.

[luvrbus]

The LCD displays doesn't work sometimes in cold weather, the Pro driver is nothing to worry about, plug the engine heater in when cold and drive on,the ProDriver is a option like a Silverleaf not a necessity, thanks Richard.The reason it starts the second time in cold weather is because the engine soaked up heat from the previous try. Instructions for the ProDriver can be found in most series 60 owner's manuals fwiw       

[Sebulba]

So you are talking about the Prodriver and not the SEL and CEL red and yellow lights on the bus dash from the main engine computer. The Prodriver is run off the DDL connector where you retrieve codes with a Prolink. It does read codes, keep track of mileage etc but should never stop the engine from starting. When you can't start and no SEL and CEL lights on the dash the main computer isn't getting power. That is the small plug you just had off the engine computer. Sounds like a bad connection there. Clean them well and dieelectric grease. Be carefull not to bend the pins. Remove fuses first.

Actually this latest issue the red and yellow lights were not lighting and the pro drive was not either.   Yes, when only the pro drive wouldn't light I could start the engine, but I didn't have some functions, like fast idle wouldn't work.

Seb

[Sebulba]

The LCD displays doesn't work sometimes in cold weather, the Pro driver is nothing to worry about, plug the engine heater in when cold and drive on,the ProDriver is a option like a Silverleaf not a necessity, thanks Richard.The reason it starts the second time in cold weather is because the engine soaked up heat from the previous try. Instructions for the ProDriver can be found in most series 60 owner's manuals fwiw     

Ok, thanks, although when the pro driver didn't come on I don't have fast idle.  Not a huge problem, I just fast idle with my foot.  Also, when it doesn't come on I don't have turn signals and some other electrical functions.

Thanks

Seb

[luvrbus]

The fast idle is linked to the cruise control they both need to be turned on with the parking brake set ,it is also linked to the B500 Allison clean the plug on the Allison electronics are fun indeed, the next time it happens turn the steering wheel one-way or the other the clock spring may have slack if you have a smart wheel (controls on the steering wheel) 

[Bill Gerrie]

Try what luvrbus said. Set the parking brake and see if you have fast idle. No then it is probably bad connection in the 30 pin plug with the 1/4" bolt in the center of it. There is two of them. Leave the one going to the engine for now. Clean the pins well but remove power at the battery for the bus. be very careful you do not bend any of the very small pins. When you insert the plug back go absolutely straight in or you will bend a few pins. Put a little dieelectric grease on them when you reassemble them. Nothing to be afraid of but make sure there is no fasteners that restrict the straight out movement of the plug. 

[luvrbus]

If your DL was setup like mine it had a switch besides the driver and one on the dash both of mine had to be in the ON position for it to work

[Sebulba]

The fast idle is linked to the cruise control they both need to be turned on with the parking brake set ,it is also linked to the B500 Allison clean the plug on the Allison electronics are fun indeed, the next time it happens turn the steering wheel one-way or the other the clock spring may have slack if you have a smart wheel (controls on the steering wheel)

OK, will do thanks for the suggestion.

I do have cruise control.  That is a can of worms I haven't explored yet, but if I understand you I need to turn it on before departure, I can't decide mid trip "I'm going to use cruise control" and turn it on?

Good to know, thanks

Seb

[luvrbus]

OK, will do thanks for the suggestion.

I do have cruise control.  That is a can of worms I haven't explored yet, but if I understand you I need to turn it on before departure, I can't decide mid trip "I'm going to use cruise control" and turn it on?

Good to know, thanks

Seb

The year model of the MCI has a setting to produce more HP and torque on cruise control you should use it as much as possiable for better performance and fuel milage with the cruise on you go from 430 hp to 470 hp