DDEC III and DDEC IV ECM memory and DDEC IV ECM battery replacements

When it comes to DDEC ecms with internal batteries (DDEC IV and up) The most common ecm component failure is the internal battery buy a mile followed by memory. Some DDEC IV software versions will trigger an active flash code 46 (SID 214): “RTC backup battery low” when the internal battery voltage drops below 2 volts. Flash code 53 Nonvolatile memory failure and/or Nonvolatile memory data incorrect (Flash 53) is triggered from an invalid checksum that’s purpose is to detect data corruption in a DDECs program. Both Flash 46 and 53 cannot be cleared while active.

Back in 2008 if a DDEC IV or DDEC V had an active fault code 46 (SID 214): “RTC backup battery low” it was believed that the ECM had to be replaced.  I had to tell the owner of that ECM that he needed to replace the ECM to correct the problem and he was looking at about $2,000 dollars. I hated giving out that bad news and I hated not being able to offer any other option. So I took some time to look into the problem.

After dissecting several cores I found that fault code 46 went active when the voltage from the internal battery to the RTC (Real Time Clock) circuit dropped below 2 volts.  As it turned out an active RTC fault was really fairly minor problem but should be taken as a warning. Want to know what\’s a lot worse than a dead internal battery in an ECM? A dead internal battery leaking acid…all over the circuit board. 

In 2009 I didn’t have a source for the OE batteries.  Instead, I used large coin cell batteries such as those found in key fobs. That procedure bought the owners of DDECs with this problem a few more years but nothing close to the life of the original battery. Besides short life these coin cell batteries had another problem. Sometimes the battery itself would pop out of it’s holder and bounce around the inside of the ECM until it shorted and shut the truck down. Coin cell and other consumer grade batteries are not anything like the commercial grade OE batteries used in these ECMs. Ever try replacing old D cells out of a Maglite only to find the batteries jammed in the tube by white oxidation? It doesn’t take more than a few years for consumer grade batteries to leak and damage to whatever they’re installed in. Now imagine how long those batteries would have lasted if they had to work while being exposed to battery killing vibration and engine heat for 50,000 hours. Under those conditions cheap batteries die quick and leak acid on the one thing we can’t replace, the circuit board. DDEC IV circuit boards are out of production and that makes them the most valuable part of an ECM. The high quality commercial grade battery designed for the DDEC IV can work in these conditions and can easily last 10 years and often reach 20. I’ll never install a coin cell or camera battery again in a DDEC because I know the problems that come with the cheaper batteries never worth it. We only use the OE batteries. If the ECM is not connected to a 12 or 24 volt unswitched supply and instead sits on a shelf somewhere the internal battery will drain faster and life will be about 10 years. If the DDEC IV is connected to a good set of truck or vehicle batteries when not in use internal battery drain will be minimal and life will exceed 10 years easily.  

**The internal battery in DDEC IV ecms is not the only part that fails over time. This service includes the replacement of all other parts other than memory that typically fail within a 10-15 year period. 

The DDEC III doesn’t have RTC battery issues like the DDEC IV. The weak link in a DDEC III is the memory. When the diagnostic code for Nonvolatile memory failure or Nonvolatile memory data incorrect (Flash 53) pops up most technicians believe an ECMs memory chip has failed and it’s time to core it. Sometimes they’re right and fuel and oil damaged a trace or component in digital processes but most of the time these DDEC IIIs are ready to be put back into service after the memory and a few other parts are replaced. If Memory failures and data corruption is allowed to go on it will get worse over time and eventually progress to a no start issue.

If those two fault codes are active and cannot be cleared then it’s not too late to save the program in your DDEC III. If you get it here soon we can probably recover it, check it for corruption then install it into the new memory. DDEC IVs can also have this problem.