Midwest ECM Repair LLC

Phone: (719)783-3399

Fax: (719)783-3397

201 Rangeview Loop

Westcliffe, CO 81252

We are still open!

We'll continue to provide you with parts to keep your rig rolling in these troubling times.


3084473, 3618046, 3619037, 3090528, 3096662, 3408300, 3408303


Tips and Pics



Is your ECM OK???

When you turn the ignition key on, the "STOP" and "CHECK" engine lights should come on, then cycle off after a couple seconds.

If the lights don't come on at all; check for 12volts in the "C" Plug (Actuator harness.  Top-inside plug) at pins 20,21,22,23, at all times, and pin 26 with the key on.  If you have power at all those pins, the ECM is bad.  If you don't have power, check the inline fuses to the right of the ECM.  Also check for a fuse in the battery box. 

Oil in your ECM

A leak at the valve cover where the injector wires pass through can let oil run down the loom and find it's way into the ECM through the actuator “C” connector. Because oil is conductive covering a circuit board with oil causes multiple components, mostly programmable memory and processing chips to short out and fail. Depending on how severe the short is this may or may not render your ECM non-rebuildable. Should you find that you have a leak allowing oil to travel down the wire loom it's best to remedy the situation before it wrecks your ECM.

Click on pics to enlarge.



Results from a water damaged ECM


Most of us have done it; you know, dropped your phone in the toilet or creek or.....  How well did it work for ya after that? Maybe some intermittent

shorting going on? So, same thing goes with ECMs.  Electronics and water just don't mix.


NO Good

Plugs from the wiring harness tend get corroded and stick in the ECM.  If you wiggle and pry back and forth too much on the harness plug, the computer circuit board can crack, rendering the ECM no good and not rebuildable.


How dead is your ECM?

There are a few different levels of non-functionality:

When you turn the key to the on position:

~ stop engine / check engine / engine warning lights come on & go back off (normal)

                         ~ stop engine / check engine / engine warning lights come on, go off & come back on (active fault)

        ~ stop engine / check engine / engine warning lights come on & stay on (ECM locked up)

                    ~ stop engine / check engine / engine warning lights don't come on at all (ECM not powering up)

It's Doing the Same Thing

Insanity: doing the same thing over and over again and expecting different results.

Albert Einstein

Hopefully when you buy a new part and install it, it fixes the problem and it's not doing the same thing. But if it is doing the same thing, would you buy that exact same part again and put it on thinking this time it would fix it? In most cases, I would think not. Most would search a different area and maybe even returning the part that didn’t fix the problem.

This is somewhat of a common thing with rebuilding or replacing ECM's. Electronic Control Modules are the brain of the engine, controlling so many different parts of the engine. So depending on the codes there are many different parts to test before finding the exact problem.

Here's a link to a neat little article about ECMs and sensors. So much that can go wrong and so much to test.

http://arksys.hubpages.com/hub/Types-of-Sensors-in-a-Car “I CHANGED THE ENGINE ITS DOING THE SAME THING, “ this guy even changed his engine. The guy writing the article suggested he looked at his sensors.

So is your truck “doing the same thing” after you put a new pricey part on it? Well I hope not but, maybe that wasn’t the problem. Do some more digging and see if you have some bad wires, or sensors that are causing your truck to run bad or not at all.

You could always have coffee with the crew and see if they have any suggestions or give Midwest ECM Repair a call and see if they can help you diagnose the problem. Maybe even send it in to get tested for free.

Keep on doing the same old thing and you expecting change,
Well is that really insanity or just a losers' game.


Cooling Plate not needed for a ECM rebuild

AND it CO$Ts more for shipping, fuel, and mechanical costs. 

However, we do have used

Cummins ECM cooling plates for purchase of $150.

Remaned or Rebuilt vs. Repair

The difference between a remanufactured or a rebuilt ECM and a repaired ECM will help you understand what your paying for, where to go and where NOT to.

The basic difference is a remanufactured ECM is totally remanufactured to the original build and exact specifications, and is tested to original equipment standards. There is nothing short in it from a new ECM, but just the name it carries, remanufactured! In the case of repaired ECM, the repair is done up to the level of failure for which there was a need of fixing; but apart from that, components are left intact. The remanufactured ECM is tested on a test station and better yet some run it on a test truck.

So the quality aspect of a remanufactured ECM is superior. All the parts of the ECM are up to the original marks and nothing is left for chance. In case of a repaired ECM, only failed and worn out and corroded parts are replaced. It directly indicates that you are at more risk of getting frustrated due to the repeated failures, which were left untouched at the time of repairing.

You should know what you're paying for. It is clear and obvious that the cost of repaired ECM is far less as compared to the remanufactured or rebuilt ECM; but as the price so is the quality. There may be additional downtime and more servicing for repaired ECM because the components are replaced as per need and not all companies test the ECM on a test station or even a test truck.

Another advantage for remanufactured ECMs is that you get a warranty period from the company. So repaired ECMs may appear alluring, but in reality, remanufactured ECMs are more quality filled and of course valuable for your money.

It is clear that the situation depends upon your requirement and what money you can spend on your ECM and truck. How much longer will this truck be used?


Broken Piston Skirt

Burnt Piston Myth

If you turn it up, you’ll burn it up,” don’t believe it

First off, all of the electronic engines have steel top pistons and they can’t burn (you also cannot burn a hole through them). We have contacted several shop owners that we do business with on a daily basis and have asked them if they have ever seen a two-piece steel top piston burn and the answer is always, “No!” However, the piston skirt is aluminum and it can break, and when that happens the piston head, which is the steel portion that doesn’t burn, goes sideways or flops over and breaks the liner. This situation is not called “burning a piston” – it’s losing a piston skirt. Yes, serious damage has occurred and now your engine needs a cylinder kit and a head, but your piston is not burned.

Lugging your engine is the main culprit of a broken piston skirt. The harmonics in an engine being lugged are far greater than in an engine that is allowed to run free. When running in the hills and mountains, use a lower gear and keep your engine at its “sweet spot” (such as 1500 or higher on the tach). You drive your truck every day and you should know the sweet spot. Your turbo boost gauge, pyrometer, amount of throttle and the feeling you get through your seat will help you to determine the sweet spot of your engine. Keep your engine at or near its sweet spot, and you’ll minimize the chances of lugging and breaking a piston skirt. By the way, it’s your engine and you should be able to do with it as you please – after all, you are the one paying for it.

Back in the early 1990’s, several low horsepower engines were built with aluminum pistons. These aluminum pistons can get a hole burnt through them (actually they crack and then the flame from the burning of the fuel burns a hole through them). This does not happen to steel top pistons. In fact, a steel top piston is so strong that if a valve breaks off, the piston will beat the broken valve into the cast iron of the head and there will be very few marks on the piston. Detroit Diesel was the first engine company to use a two-piece steel top piston. Today, all of the Detroit, Caterpillar and Cummins pistons are made by the same company called Mahle, which is based out of Michigan. So we all have something to thank the Detroit Diesel engineers for – the invention of the two-piece steel top piston.

All of the older mechanical Cummins and Caterpillar engines have aluminum pistons and that is why they coat them with ceramic and Teflon. The ceramic on the top of the piston reflects heat and keeps it in the combustion chamber to better burn the fuel and the Teflon on the skirt allows the piston to move more freely in the cylinder liner. You also can coat the newer steel top pistons and aluminum skirts with the same coating. It is a two-week process to coat the pistons.

So the next time a service manager or mechanic tells you you’re going to burn it down or burn a piston in your electronic engine if you turn it up, just ask him if he has ever seen a burned steel top piston. If he says yes, ask to see it (and then please send it to us because we would love to see it, too). If he says yes, you pretty much know that he is lying, so should you trust anything else he has say?

Don’t forget, When dealing with high performance products for your engine, trust your instincts and your gut feelings.

Broken Piston Skirt

Water in Diesel Fuel


Water in Diesel fuel

You need to protect your truck / fleet against slimy HUMbugs, engine misfires and disastrous downtime. Check into this issue that normally only receives attention when it's too late - water in diesel fuel. It's particularly important to look at this issue when there have been floods that could have contaminated diesel fuel storage sites all over the country. The good news is that fleet operators can be much more proactive than merely calling in their fuel suppliers to conduct checks when engine damage is widespread. Water in diesel fuel also favors the growth of HUMbugs - yes there is such a term - that shortens filter life and when winter hits, it is good to know that ice crystals can block the system in extreme cold. Don't be a victim - fight the slimy HUMbug urges.

Anyone who has experienced water contamination in diesel fuel supply tanks knows this can cost a lot of money per engine in damage to fuel injection systems - and then add to that figure for the day or two off the road in lost production. If the water has been able to by-pass the water trap separator on a Cummins L10, M11 or N14 engine, the damage to fuel injection systems will cost a bunch.

Diesel fuel acts as lubricant for injector pumps and injectors and the presence of water causes rust and seizures. Electronically controlled engines experience spring breakage inside the injectors. What stares at you through all of this is the replacement of injectors, fuel pipes, fuel pumps and trucks limping home on reduced power.

The multiplying effect of water contamination in a fleet of diesel powered vehicles is horrific. It can, in fact, bring a business to a smoky halt. Whether the fleet is young or old, the fact remains that this type of damage is not covered by warranty. You are on your own with the consequences.

The cascade of events that leads to water in diesel starts with a dirty yard that has blocked drainage outlets. A wet summer floods the transport yard and swamps the fuel storage tank sump covers which, in turn, have never been correctly fastened down and checked for perfect sealing. A devil's engine brew is thus mixed and prepared for dispensing to the fleet.

Water is the most common contaminant that accumulates in fuel through the simple lack of monitoring of storage systems. Ever present in the atmosphere, water ingress can also result from:

  • Storage tanks breathing in humid air after a temperature change.

  • Water in the air condensing when the temperature drops.

  • Dissolved water separating out when the temperature of diesel fuel drops.

  • Condensation also occurs as hot fuel returning from injectors flows back into the cooler fuel tank. As the temperature decreases, fuel holds less dissolved moisture. Free water in liquid form is heavier than diesel fuel and settles in the slow flow, or low areas of a fuel system.

  • Water leaking in fuel tanks during transport - poor housekeeping practices on the part of suppliers can be a major undetected contributor to the problem.

Water in fuel allows the existence of fungus and bacteria that live in the water while feeding off the hydrocarbons found in fuel. These contaminants are called Hydrocarbon Utilizing Microorganisms, or go by the acronym of HUMbugs.

A microbial problem is evident when the spores become active and multiply forming colonies and mats of growth. Colonies then spread through the fuel system wherever moisture, or even trace amounts of moisture are present.

Bacterial problems in fuel are characterized by shorter fuel filter life, evidenced through black slime over the entire surface of the filter media. Draining the fuel system will reduce microbial activity but not eliminate it. Once microbial activity has started in a diesel fuel system, the only way to eliminate it is to treat the system with a biocide. Biocides are classed as very hazardous substances and should be used in consultation with your fuel supplier. Laboratory tests will confirm the presence of HUMbugs.

Here are a few suggestions that should form part of daily operational procedures to hold the slimy HUMbugs at bay:

    • Purchase fuel from reputable suppliers to a guaranteed specification.

    • Install good housekeeping procedures - cleanliness, drainage, secure sealing of inlet valves, breathers that are unclogged and do not draw in contaminants.

    • Check the fuel tanks for water just before, then some time after delivery. Regular checks should also be made using 'water finding paste' to accurately detect the presence of water. Visual checks are too imprecise.

    • Ensure that the fleet, regardless of age, is equipped with water trap separators. Modern trucks, even down to the small Toyota Dyna and Mercedes-Benz Sprinter are equipped with water trap separators and warning lights on the driving console. Cummins Engine Company wrote this into their specifications with effect from September 1991.

    • Train your drivers and maintenance staff on the importance of ensuring that water trap separators are attended to regularly - and what the warning lights are telling them. Don't neglect this and only attend to it when a breakdown occurs.

  • Keep fuel tanks filled up when parking vehicles overnight. The condensation that forms in an empty diesel fuel tank at night with a drop in temperature is a problem in some areas.

Fuel Shutoff Solenoid

The fuel shutoff solenoid is one of the components that can take out an ECM. The ECM supplies +12v to the fuel shutoff solenoid through pin 16 on the actuator / injector harness (C-Plug) when it has +12v on pins 20, 21, 22 & 23 and also +12v on pin 26 from the ignition key. Not only does the ECM supply the +12v it also monitors it. If the coil inside the solenoid fails it can short to ground via the housing. This in turn starts pulling down the +12v. The ECM will ramp up amperage in an attempt to maintain 12v on pin 16. The ECM will actually burn itself up attempting to push +12v.

It's a good idea and cheap insurance to change your fuel shutoff solenoid when installing a new ECM.



Cummins Celect and Celect Plus Harness Connections

Celect and Celect Plus have different plugs, kind of like your home computer, so you cant mess it up.  Well of course it still happens.  Both Cummins Celect and Cummins Celect Plus ECM's have three wiring harness connections with 28 pins each.  Always check to make sure your plug is seated securely and making good contact (not too much lube).  Too much grease or incorrect grease, used to waterproof, can cause connectivity problems. A light film of dielectric grease is all that's necessary. Sometimes one of the 28 pins can get bent when plugging and unplugging the connectors for trouble shooting also causing connectivity problems.  Inside each connector is 28 female ends, these become dirty, corroded and stretched over time which makes for a poor electrical connection and can cause intermittent problems.  Spraying electronic contact cleaner into the harness ends and blowing out the dirt can help maintain a proper connection.

Cummins Celect Plugs and Ends

Celect Plus Plug and Ends

The 28 Pins and the Connectors

The A plug or the sensor connector is the one on the bottom outboard from the block when the ECM is mounted on the engine.  This connector houses engine position, coolant Temperature, coolant level, ambient air temperature, ambient air pressure, manifold air temperature, boost pressure, oil temperature, oil pressure along with connections from control data links, service tool data links and diagnostic signals.

The Second one is the OEM connector of B plug.  This one is on the top, outboard from the block when mounted on the engine.  This harness houses the vehicle speed data, tachometer, idle validation, throttle position along with all the cab switches - clutch, brake, cruise on/off, cruise set/resume, engine brake, idle increment/decrement.  This connector also provides the signal to the stop engine, check engine & engine protection lamps.

The third is the actuator connector of C plug, often called the injector harness.  This one is on the top inboard toward the block when mounted on the engine.  This connector houses the four un-switched +12v lines, the key switch +12v line, three battery returns or grounds, the power wires for the fuel solenoid, engine brakes and the fan clutch.  This connector also has supply and return lines for all six injectors.

Did a Hurricane get your Truck?

Salt water destroys electronic components faster than anything else.  We've had several ECM's come to us from the Eastern Seaboard following super storm Sandy.  Here's some pictures of what's happened to the ECM's.  You can imagine if the inside of the ECM looks like this, there's extensive corrosion damage to the wiring harness & sensors.  Just replacing the ECM in these circumstances usually doesn't completely fix the truck.

Burnt ECM's