8 Things You Need to Know About Your ECM


It wasn't too long ago that cars were just pieces of machinery, albeit finely-tuned and engineered pieces of machinery. Today, cars are 3,000-pound rolling computers and the ECM market is still growing.

We live in a high-tech world and ECMs are in every car manufactured but are still one of the most confusing elements of an automobile to grasp.

We're going to walk you through eight things you need to know about one of the most popular engine control modules on the market, the Cummins ECM.

Computer-Based Systems Have Been Around Longer Than You Think

The shift from all-mechanical to electronic-based systems may feel like it happened overnight. We have push-button ignitions and remote starts, things that weren't around 15 years ago, but computer-operated cars isn't an invention of the 21st century.

It's been a slow-growing process that began in the 1900s. Electronic ignitions got introduced in the 1940s and were an option on some General Motors models in the 1960s. But, the word "electronic" doesn't mean "computer," it means some of the components in the ignition were replaced with more reliable parts.

Now, you're probably thinking back to all those "electronic" parts automakers touted and are wondering if any of them were computers. The ignition wasn't one, but what about electronically-controlled distributors? Another red herring.

The Electrojector was the first electronic fuel injection system designed for a production car - the 1957 AMC Rambler, to be exact. Unfortunately, it didn't work and never actually made it to production.

Chrysler built 35 prototypes with Electrojectors for some of their 1958 models but then they realized they weren't reliable and replaced them with carburetors.

In 1968, Volkswagon put the Jetronic electronic fuel injection system into their Type III Fastback and Squareback models. The Jetronic used data from a pressure sensor, along with engine speed, to control the fuel injection rate. Voila! The first computer-based system was born.

Today We Have ECMs

ECM is short for engine control module and is also called an engine control unit (ECU).

In a nutshell, you can consider the ECM as your vehicle's brain. That brain is growing, learning, and making better decisions than ever before. Before we know it, self-driving cars will be as common as smartphones.

We're not there yet, but no one thought Michael talking to KITT with the Trans Am responding was a reality back in 1982, either. Now, you can tell your car to make phone calls, change the radio station, or adjust the temperature and it does.

So What Does the ECM Do?

Growing at a rate of 6% annually, it's important to know what an ECM is and what it does, aside from knowing it's "the brain." It involves software and hardware and controls one or more of the electrical and engine systems in your vehicle.

A Cummins ECM controls:

  • Emissions
  • Variable cam timing
  • Fuel mixture

It also plays a part in the following processes:

  • Interacts with the transmission controller
  • Oversees the operation of the cooling fan, fuel pump, and the charging system

So, while we think of computers in cars as voice-activated commands, power windows, and adjustable seats, it's actually making your engine work.

Troubleshooting a Cummins ECM

There are elements of your Cummins ECM that you should know a little more in-depth, like troubleshooting when you sense something isn't operating correctly or on its last legs.

Your Cummins ECM, or any engine control module, can be replaced or repaired but jumping the gun and removing one without knowing for sure can cause some undue headaches.

Here are a few signs something is wrong with your ECM:

1. You're Having Trouble Starting the Engine

Spark, fuel, and compression make a vehicle run and the engine control unit is responsible for properly delivering the fuel for the spark. The ECM receives several data which it computes into determining the amount of fuel to be injected into the engine.

On vehicles with variable valve timing, the ECM helps maintain proper compression. Because the ECM plays a part in all three functions, if something's wrong, your engine won't start.

2. The Check Engine Light is On

It's random, annoying, and often ignored, although it shouldn't be. Engine modules communicate with the ECM, sending signals that it's running smoothly and everything is okay.

When it can't communicate with the engine control module, it sets a diagnostic trouble code and the check engine light comes on. You read the fault code from the ECM, find out what the code means, and repair/replace it.

If something is wrong with the ECM itself, like its misinterpreting data, the check engine light will also come on.

3. Engine Isn't Running Right or Stalls

You already know that the ECM handles emissions and fuel, among other things. If the computer is faulty, these things won't work properly and your engine will misfire, stall, or surge.

Here's what could be causing the damage:

1. Starter Issues

A lot of auto parts are "interchangeable," or will "work in a pinch." But, not always and the starter is one of them. When a starter is replaced with the wrong model, the override sensor in the starter is bypassed.

The override sensor regulates voltage, so if it's bypassed, voltage issues occur. This leads to fault codes, followed by that darn check engine light turning on.

2. Battery Cells are Dead

Dead battery cells left in the rig for too long affect the grounding in the battery, which causes the ECM to malfunction.

3. You've Recently Had a Jump Start

If the cables weren't connected correctly during a jump start, the ECM can spike and short out.

4. Corrosion and Moisture

Damage or corrosion due to moisture in one of the most common reasons the ECM goes bad. Think of it like spilled coffee on your laptop or dropping your phone into water will ruin your devices.

Over a period of time, the ECM seals start to wear and moisture can get inside while corrosion can get in through the wiring harness. If your vehicle is more than 10 years old, it's been exposed to a lot of weather elements and this is a part of normal wear and tear.

5. Fuel Solenoid

If corrosion isn't eating away at your ECM, it could be affecting the fuel solenoid, which causes the ECM to fail. It's located at the top of the fuel pump and when corrosion gets inside the solenoid or the wiring to the ECM, it will short out the engine control module.

Broadest Range of Applications in the Business

You need to rely on your ECM and that's where we come in. We guarantee that you will receive an ECM that is 100% inspected, tested, and put through the most extreme conditions imaginable to get you the product reliability you deserve.

We offer a wide range of Cummins ECMs from Signature/ISX to Cummins Celect to choose from. We also offer computer rebuild and restoration with a 1-2 day turnaround.

Visit our blog for troubleshooting ideas, contact us with any questions using our online form, or give us a call at 1-877-602-8104.

Posted On: 05/08/2018

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