My biggest knightmare: DD50 Starting Woes

[moosemanusa]

I decided to document this issue so I don't miss anything:

Back story:

Bus never had any problems, engine only has 30k on it (rebuilt)
Driver was not pre-checking and oil ran on the low side, driving down the highway engine went into a shutdown protection mode, driver pulled over.
Driver added oil, bus started and oil pressure light came on and stayed on. (although wouldn't start from the front, only started on the rear run box)

A few weeks later, driver used bus, was parked up shut down the engine, engine 1 hour later would not start up.

From heavy cranking bus eventually fired up.  Bus worked fine (all bar oil pressure light still on – oil levels good) for 2 hours after..

Parked bus, left for 3 weeks.

Latest developments:

Bus would not crank, removed starter, started was fried.
New starter installed, noticed the CEL or SEL no longer illuminated upon ignition. (due to no real eyes on a pre-check inspection we have no idea how long the CEL or SEL have not come up or if that was a new issue).

Oil pressure light still on, cranks engine, goes to fire up, then goes back to a crank status!

Fuel system checked fully, pump is good, filters good.  I know its not the fuel system as this CEL AND SEL not coming are an issue.

Brand new charged batteries installed, breakers all test good and have voltage running over them.

Any idea's guys, I've posted all around and even chatted with some great peeps with DDEC knowledge but internet troubleshooting only goes so far.. The ECM has good voltage going to it.

I found a user who had a similar problem but no resolution was posted (or I missed it)..

I have DDDL working (the old version for the DDEC IV) but the bus is 1200 miles away so trying to get a book full of ideas to try..

Thanks, Moose

[luvrbus]

Where the codes ever cleared after the shutdown ? 

[moosemanusa]

Negative, didnt have access to a DDR, have since obtained the DDDL software and that should work with my Cummins Inline 6 with 5 pin Deutch to connect.

Would the 255 count (max for PID code count) stop the CEL and SEL from coming on when the ignition is on ?

The engine fired up after the shut down, the only difference is the oil pressure light is on (ordered new oil pressure sensor).

Thanks.

[Zeroclearance]

You might want to CHECK your oil pressure with a gauge.    Use one of the pressure taps..

I'd be curious to spin off a oil filter and check for debris?  Check and see if it's packed with bearing material.

[moosemanusa]

Bus has a steam oil pressure guage in the back luckily, pressure comes up as the motor cranks.

Haven't checked for debris in the filters yet.

Does anyone have the wiring schems for a 96 Novabus (its the year where Nova purchased the old TMC RTS's and installed the D50 in them.

I'm still thinking the problem is related to the CEL / SEL not illuminating on ignition (when it should), lights test good as there's a test button.

[blue_goose]

Sounds like you are getting Ignition voltage.
Jack

[stevet903]

If the CEL/SEL does not come on when the ignition is switched on for at least some amount of time, and the lights are good with the test button, I would say that the ECM is not getting power or it is fried.  There should be two fuses or breakers that supply power to the ECM that need to be checked, as well as three grounds that come off of the power connector to the ECM.  They are supposed to be run directly to the batteries.  Could the grounds have been left off when the batteries were changed?  Check the power at the ECM power connector - it has five pins.   Here is the troubleshooting manual - http://www.dmbruss.com/images/Schematics/DDEC/
- Steve

[moosemanusa]

Finally Got there..

Drive the 1200 miles out there, turned on the batteries and suddenly the CEL and SEL where working again! still no start but they were flashing the code (SEL 25) which means, "hey no problems here" the Oil pressure light was still on.. DDDL refused to connect to the ECM.

So pulled the ECM and took it to a store, they stated the board had a low voltage issue (I believe there's a battery on there also which was probably bad), so they handed me a rebuilt ECM and I gave them 950 bucks! yes its 250 more than anyone else but they did it within 45 minutes and everyone else needed 4 to 6 working days..

Installed ECM, oil pressure light was gone (with the old ECM it didn't even report a bad oil pressure signal)

bus still wouldn't start..

So after some cursing, pulling hair etc etc (well maybe not that part)

I had a flash in my mind to pull the diesel line to the head just to check one more the fuel flow (done this no less than 10 times already), cranked the engine, diesel started spraying out, plugged the end with my thumb, reconnected the line, said a quick prayer to the diesel engine gods and hit the starter.. She started straight up! Little bit of black smoke and she purred into life!

I'm thinking there's been a couple of issues..

Low oil in the motor caused the ECM to lock up, for some odd reason the ECM refused to re-dedect the change in oil pressure and in its funny kinda broken state stopped the engine from starting..

The check valve on the fuel return line is going bad (hence the loss of prime), its a common fault with the D50/D60's and its a 12 dollar part (worth changing)..

Low batteries fried the Delco starter (new starter is fine with the fresh new Duracells)

So thanks to everyone who assisted, I was privileged to speak to some great people and a DDEC expert (I wont name him) but I love it when a board comes together for a stranger!

[eagle19952]

did you keep the old ECM ?

[moosemanusa]

nope it was an exchange..

I know with time (which I didnt have) I probably could have found the problem, soldered a new battery...

I would like to get one and play around with it on a bench setup..