DDEC II

[Cary and Don]

Spent some time with the ohm meter checking breakers for continuity.  Checked all the cube relays with a relay checker. Everything seems to have breakers and not fuses.  So far all the readings are .3 ohm or lower.  Found one bad one,  but that was on the back up lights.  The ground wires on the six way ddec box showed .3ohms.  Grounded to the body for the checks. 

The only thing that seems different is the check engine light is staying on a shorter period every time we turn on the run switch.

Cary

[Cary and Don]

Well, we have been reading to trouble shooting book.  Clifford has it right.  600 pages of not much help.  Anybody have any more ideas?  Maybe some place we can pick up another ddec unit.

Cary

[Hard Headed Ken]

This is my best guess. Back probe the ECM power connector with the ignition on and everything connected. If you have battery voltage between the power supplies and grounds and still no starting it's likely the ECM is fried.

Ken

[Cary and Don]

Yes,  it has power on the six way power connector.

Another question.  If the thing is fried,  how hard would it be to change to DDEC IV?  Everybody seems to think that is better.

Don and Cary

[belfert]

I'm no DDEC expert, but could a Detroit dealer test your DDEC to see if it is working or not before you spend money on another one?

[B_K]

What engine is this for? If it's an 8V92 I may have one still one an engine in a bus I'm parting out.
I have no idea if it's good or not. Supposedly the engine was running when they took the bus out of service do to water in oil. But I have no proof of this.
  BK 

[hargreaves]

One side of the power connector will feed one bank of injectors , the other side will feed the other bank. the ground wires in the middle of the connector should go directly to battery ground.

If you make up a wiring harness that fits the ECM power plug and connect it to a separate battery and crank the engine over if the engine starts check your wiring  if it doesn't , the ECM is fried.  I think the connector that connects the Throttle position sensor is the same configuration as the ECM  power plug.  Cheers Gerry

[Cary and Don]

Yes, this is a 8v92 turbo in a Neoplan.  The transmission is a 748 with a retarder if that makes any difference.

The power is going into the box, but obviously,  nothing coming out the other side.

Don and Cary

[brmax]

Hey guys whats the norm for getting codes the old fashion way with that diag button. If I might ad some other trucks you hold the button in and turn the key on then count the blinks, or some just read the description. I am going to look around for a pin out schematic for a 92 year model with a 6v I suppose it would have both models very close to the same. I will try to help out when i get some tips Keep up the good work.
Later