​DDEC Misfires And Backfires: Issues With Timing Signal Processing Or DDEC SRS Disease

Fernando DeMoura
December 2016

Years ago I started changing batteries in DDEC IV ecms to cure one of the most common failures DDEC IVs have. The second most common failure these ECMs have is an intermittent injector misfire or a no start condition. Most of the time this problem ends up being mechanical but I have seen many DDEC III and IV ECMs also be responsible and it doesn’t always set a check engine light. The problem I am taking about is related to the processing of the synchronous reference sensor (timing signal) input. I used to call it “SRS” disease and I stored all the DDECs that had this problem in a huge file cabinet hopeful one day I would find a cure for it.

Over the last six months I have been studying DDECs with SRS disease on the ECM dyno. I’ve been letting them run all night, looking over the misfire counts in the morning, and replacing and upgrading associated signal processing parts. At this point I can cure 4 out of 5 DDECs that have this problem. Reman OEM DDEC III and IV hardware hasn’t changed much in the last decade but microprocessor technology has. In most cases, I’ve found these upgraded DDEC IIIs and IVs firing more accurately than reman units that are only a few months old. I’ve been making this upgrade standard for all DCS remanufactured DDEC IIIs and DDEC IVs for the last two months and I will soon be offering it as a standard service to all DDEC III and DDEC IV models.

If you have an old DDEC III that is giving you trouble or flashing a code 53 consider getting it repaired. DDEC IIIs and industrial DDEC IVs are no longer being produced. The reman industrial DDEC IVs do not have a new circuit board in them. They are actually repaired units. As far as DDEC IIIs the factory replacement is a DDEC IV. Regardless of what your dealer might tell you the DDEC IV ecm program you get when you core your DDEC III ecm will not be the same as your original program. DDEC IIIs are more difficult to repair then DDEC IVs but there’re are only so many of these great ECMs left and as long as your DDECs memory is intact your program will not be altered by any DCS ECM hardware repair services.

I’d rather turn down a job than accept a job and not be able to give it the attention it deserves. I’ve recently decided to focus my research efforts exclusively on DDEC IIIs and DDEC IVs for the next few months. I’ve been getting so much DDEC work that I’ve needed to focus on streamlining DDEC III and DDEC IV repair and programming efficiency. I still offer programming services for Caterpillar ECMs but Caterpillar, Cummins, and DDEC V repairs are on hold until the current workload of repairs has been completed.

Written by Fernando DeMoura, Diesel Control Service LLC., www.dieselcontrolservice.com Phone 412-327-9400