DDEC III & DDEC IV ecm repair and component replacement

When the circuit board or major circuit board component in a DDEC III or IV suffers damage that results in the loss of some or all ecm functions then replacing the damaged ECM and programming the replacement is often the only option.  Other times depending on the severity and location of the damage an ECM circuit board repair could be attempted to reconstruct the damaged section of circuit board and replace any damage components to restore road worthiness and full ECM functionality. Many of the major components inside a DDEC III or DDEC IV had an expected service life of 50 years or more however something like the primary microprocessor or the analog to digital converter can be damaged and fail because it was connected to another component or section of circuit board that was damaged. Component failure usually comes down to too much heat, too much current, a build up of oxidation from water, battery acid, or exposure to voltage that exceeded the components maximum rated voltage. Sometimes the damage is immediately obvious and sometimes it isn’t and requires component specific tests to locate and be identified. The demand for DDEC III and DDEC IV repairs at DCS is growing and thanks in part to advanced inspection, diagnostic and microsoldering tools make microscope aided repairs to trace packed sections of circuit board and fine pitch components feasible and all other repairs more precise and reliable. The net result is more DDEC repairs are go back on the road and less to the core pile.

DDEC III and DDEC IV ecm “rebuild” service has been retired and replaced by DDEC IV battery and memory replacement. Those who were familiar with what the ecm rebuild service was as I had it defined in the paragraph below will realize the only thing that actually changed was the name. The words “ECM rebuild” is confusing which is why for the last 8 or so years I included a paragraph or two to underneath the ECM rebuild service section defining what an ecm rebuild service is. ….but it wasn’t enough. Despite what I define in the ecm rebuild section around 9 out of 10 requests for DDEC III or DDEC IV ecm rebuild service were coming in with a loss of ecm hardware function and with damage to the circuit board. Or with no known history. Many in the second category were junkyard ecm flippers that didn’t even own a truck but had some other replace all, fix all, catch all idea of what a rebuilt ecm was. Some even said a rebuilt was the removal and replacement of every circuit board component. It takes over 600 degrees to remove a circuit board component and most components are rated to a maximum temperature of 200 degrees. Also 18-25 year old plastic laminated circuit boards fall apart with repeated exposure to 600 degree temperatures. If dropping ECM rebuild service helps draw less of those catch all junk yard flippers then it’s worth it.

I define a rebuild as the replacement of any or all component(s) that is close to reaching or have already reached the end of it’s recommended service life as defined by the manufacturer of that component. That’s usually DDEC III memory, some DDEC IV Memory and most DDEC IV batteries and a few other parts. I’ve seen in some Detroit reman ecms that make me feel pretty good about that standard.

Below is a 2012 reman DDEC IV E01 and a 1998 DDEC IV E01. Motorola made the DDEC IV from 1998 to 1999 before another manufacturer took over. Every component in the 2012 reman DDEC IV has the same 1998 build date as the 1998 DDEC IV except the battery.

I made a repair and replaced the memory and battery in a DDEC IV with over 2 million miles logged in 2019. Five years later it’s still on the road. Mileage doesn’t bother a DDEC IV as long as it stays clean, dry, and doesn’t get too hot.

Not all ecms are worth a repair. The DDEC IV ecm above lhave been destroyed by heat and by leaking acid from it’s own internal battery. Both are too far gone to consider repairing