DDEC Issue again...

[Sebulba]

Hello all,

I had a thread a while ago that you all helped me with and on out trip form MN to OK all was well.  We stayed in OK for a month and when I went to start the DDEC dispaly didn't come on right away.  I started anyway and aired up then shut off and started again and the DDEC lit up.

We drove to Canadian, Texas yesterday and again the DDEC isn't lighting up, and the 'Check Engine' and 'Stop Engine' lights aren't lighting either when I turn on main power.

Unable to start.  This might possibly be because I didn't plug in the block heater last night (I normally do, just got lazy), but could it be something else since the 'Check Engine and 'Stop Engine' lights aren't lighting?  I'm pretty sure that they lit yesterday even though the DDEC wasn't lit.

Hope that makes sense. 

Any insight or ideas?

Seb

[Bill Gerrie]

Check the DDEC unit for a bad or  corroded ground. Bad connections are the electronic engines worst enemy.

[Sebulba]

Check the DDEC unit for a bad or  corroded ground. Bad connections are the electronic engines worst enemy.

As with anything electrical.  Grounds are often the culprit.  I looked at the DDEC computer on the side of the engine and see no ground wire coming off of it where do you think would be the best place to look?

Thanks

Seb

[Sebulba]

As I have been thinking about this today, in the past I could start it without the DDEC lighting up and then after air up shut down and when I start again the DDEC lights up.  Now I am unable to start.

It's almost 60 degree here so I don't think it's the temp, especially since no cylinders are even trying.

Any ideas?

Thanks

[robertglines1]

I have ddec IV the ground comes thru wire harness to computer. Search Detroit diesel DDEC IV wiring diagram it will give you wire number and location on ddec computer.  The ground is internal to computer case.

[Sebulba]

I have ddec IV the ground comes thru wire harness to computer. Search Detroit diesel DDEC IV wiring diagram it will give you wire number and location on ddec computer.  The ground is internal to computer case.

Inside the DDEC Box mounted on the side of the engine is what you're saying, I think?  I'm very new to MCI.   Bought this rig a year ago -- learning.

So, must take the DDEC box off the side of the engine, open it an look inside?  Am I on the right track?

Thanks

Seb 

[Sebulba]

Aaaarggg!   OK, this is really annoying me.

Just because I'm a guy who always has hope, I tried to start the rig again and DDEC lit and the Stop and Warning lights lit like usual and she barked right off like normal.

Since it's late in the day and we don't like driving at night I just let it air up and put some 2 x 8 under the tires to be more level for the night and shut her down.  Then I went to start again and NO DDEC lights or Stop or Warning lights.

I sure would like to get to the bottom of this. 

Before it started this time, the only possible change is that I was looking at the DDEC mounted on the side of the engine and wiggling the wires a bit as I looked at how to disconnect them.  Don't know if that was a factor or not.

If anyone has any ideas I sure would appreciate it.  We are "hopefully" going to get started early tomorrow and get to Albuquerque, or final destination for a while, so that we aren't stressed since we need to be there by this weekend.

Would this be an issue that a guy with a computer could figure it out, or...?

Could it be the the Computer is acting up and needs to be replaced? 

Thanks

Seb

[Bill Gerrie]

DO NOT OPEN THE COMPUTER. You should get a DDEC book. I thought last time you were having the same issues. The wires that feed the power and grounds associated should be gone over and cleaned and electrical grease applied to them. When you have a not light issue have somebody watch the dash while you move wires associated with the power source to the computer. Usually near the batteries. The breakers for the DDEC computer come directly from the batteries. Grounds also directly from the batteries negative side

[luvrbus]

Have you ever noticed was the transmission shifting pad lit when the  engine wasn't lit ? ,a shift pad with glitches or no power on a B500 will stop all functions on a DDEC and will not let one start 

[robertglines1]

no look inside...!! nothing to see. sealed.  just trying to provide path of power and ground to ecm.. you need to hook up with someone that understands ddec--- bus nut  --- truck nut---that is a high dollar ecm prob over 1500$$$ used minimum plus possible need to be programed..  Maybe a local charter operator??   Bob

[Sebulba]

Have you ever noticed was the transmission shifting pad lit when the  engine wasn't lit ? ,a shift pad with glitches or no power on a B500 will stop all functions on a DDEC and will not let one start

Never noticed, but will take note of that next time.

Thanks

Seb

[Sebulba]

DO NOT OPEN THE COMPUTER. You should get a DDEC book. I thought last time you were having the same issues. The wires that feed the power and grounds associated should be gone over and cleaned and electrical grease applied to them. When you have a not light issue have somebody watch the dash while you move wires associated with the power source to the computer. Usually near the batteries. The breakers for the DDEC computer come directly from the batteries. Grounds also directly from the batteries negative side

Up till today it would start when the DDEC wasn't lit up.  Today it wouldn't even start.

OK, good suggestion to have somebody watch the dash wile moving wires.

The breakers for the DDEC -- are they in the battery box, or where would be the best place to look for those?  Assuming I find them and connectors/terminals, I am guessing I can disconnect, clean apply electrical grease and reconnect?

Yes, I should get a DDEC book. I have so much to learn...

Thank you so much for the help.

[Sebulba]

Have you ever noticed was the transmission shifting pad lit when the  engine wasn't lit ? ,a shift pad with glitches or no power on a B500 will stop all functions on a DDEC and will not let one start

Never noticed, but will take note of that next time.

Thanks

Seb

I just tried it.  When I turned on the main power switch just now.  No DDEC, no Stop or Warning lights, but both "N"s showed on the shift pad.

Thanks for the suggestion.

Seb

[Sebulba]

DO NOT OPEN THE COMPUTER. You should get a DDEC book. I thought last time you were having the same issues. The wires that feed the power and grounds associated should be gone over and cleaned and electrical grease applied to them. When you have a not light issue have somebody watch the dash while you move wires associated with the power source to the computer. Usually near the batteries. The breakers for the DDEC computer come directly from the batteries. Grounds also directly from the batteries negative side

I see these covers with terminals under them.  Is the DDEC 12 volts?  Are these the one that may be the culprits.  All of the others that I can see are quite large cables, these look like 10 or 12 guage or so to me.

[Bill Gerrie]

The power and ground usually are 12 gauge wires. Luvrbus would have more knowledge with MCIs then I do. My Bus is a GMC so the DDEC set up probably is a little different.