Detroit Diesel ECUs Explained: What Do Different DDEC Versions Do?

Have you ever put much thought into what's controlling your engine? It may run on diesel, but it's probably controlled by electronics. Unless you're running a much older engine, of course.

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The rise of these systems have allowed for better control and monitoring of the failures within your engine, giving you a better idea of the problematic systems without nearly as much troubleshooting. 

In this post, we're taking you through where these systems started and what they can do for your engine. 

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What is an ECU?

The ECU (electronic control unit) does exactly what it sounds like—it controls the systems in your engine, electronically.

R23519307 Detroit Diesel DDEC IV ECU RemanufacturedThese systems can be hooked up to a computer, and technicians can read the failure codes to better identify what's going wrong. They also allow for improved engine function and features, like better horsepower and cruise control functionality.

How Did the ECU Come About?

While ECU's have been around for a while in the automotive market, Detroit Diesel is the company that really brought them into the diesel engine market with their Series 60 engines. 

First seen in 1986, these engines were the first diesel engines to feature an electronic control system. 

This innovative system, the Detroit Diesel Electronic Control system (DDEC) allowed for greater control of injection timing and maintenance monitoring. 

It also helped the engines remain compliant with the continuing emission regulations from the EPA by allowing for increased performance from engine advancements.

Just as Detroit released several different engines in its Series 60 line, through the years, they came out with multiple versions of the DDEC. 

Various changes were made to the systems, and the different versions came to be known as DDEC I, II, III, IV, V, and so on. Each variation brought with it changes and new engine capabilities, forever altering the way diesel engines run.

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WHAT DID THE DIFFERENT DDEC VERSIONS DO?

Overall, the changes made to the DDEC were meant to improve engine performance or capacity, with increased horsepower being a common shift between versions, or to better meet new emission standards. 

Below is a brief overview of the differences between the releases of the DDEC.

1. DDEC I

The DDEC I, as you can guess, is the first version of Detroit's ECU. It was a 12-volt, two-box system, with an ECM in the cab and an EDM on the engine. 

It controlled timing and fuel injection, as well provided better system monitoring. It was, however, quickly replaced by the DDEC II.

2. DDEC II

This version has similar features to the DDEC I, in that it is a 12-volt system that controls injection and system monitoring. 

Detroit did, however, make the switch from two boxes to just one. 

It also came with a cruise control option that made for a more economical engine. The ECM had more functionality and could actuate the solenoids.

3. DDEC III

The release of the DDEC III brought improved horsepower. The system switched from a 12-volt to a dual-voltage ECM. 

It has improved adaptability as well. This version is significantly different from its predecessors. 

It operates via electronic inputs from sensors, which give the ECM the information it needs to control the engine. 

It has a more precise fuel timing control, using predetermined values. It has better control info and compatibility.

4. DDEC IV

This version operates in a similar way to the DDEC III, but its release further increased horsepower and torque. 

It came out at the same time as other improvements to the Series 60 line. Detroit made some changes to IV while it was still being produced, so some earlier versions might operate differently.

5. DDEC V AND ON

More changes have been made to the DDEC systems recently, in order to increase engine efficiency and power, and, as is the case with the DDEC VI, to meet new emission standards. 

These ECUs could be found in the later Series 60 14L applications, before the line was discontinued in 2011.

 

Current Use of Electronic control units

Despite its initial development for the Series 60, DDEC units are still being used in Detroit's DD line of engines. And Detroit no longer has the only engines on the market with ECUs. Electronic control is the standard of modern diesel engines.

 

Highway & Heavy Parts is Here to Help With Your ECUs

If you're experiencing trouble with your ECU, HHP has the knowledge to help you get the parts you need for your repair.

When you shop at Highway & Heavy Parts, you'll have access to:

  • ASE Certified Technicians on staff to help diagnose your diesel engine problems

  • Fast and accurate quotes

  • A huge inventory of replacement parts

  • Fast and easy ordering—call or shop online!

  • Fast shipping

  • Industry leading warranties

From diagnosis through delivery, we're Highway & Heavy Parts!

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Detroit Diesel Resources

Related Articles:

THE 7 MOST COMMON DETROIT DIESEL S60 PROBLEMS AND FAILURES

WHAT'S THE DIFFERENCE BETWEEN DETROIT DIESEL SERIES 60 12.7L AND 14L ENGINES

DETROIT DIESEL DD15 FUEL INJECTOR: FAILURES, INSTALL TIPS, AND PART OPTIONS

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