7 Common Reasons for a Failing Diesel ECM



Common Reasons for a Failing Diesel ECM



The diesel ECM is the beating heart of your vehicle. Whether it's a big rig or family SUV, this part monitors data from a range of sensors and makes tweaks to ensure performance and efficiency.

For example, the ECM maintains cruise control speeds. It can limit engine RPM from a cold start to protect it until it works its way up to the optimal temperature. And it controls fuel mixture and controls the emissions coming from your vehicle.

The diesel market is looking up, which means that there'll soon be far more diesel vehicles on the road. In turn, that means a lot of new diesel owners wondering how best to care for their diesel engine and ECM.

Here are 7 of the most common reasons behind diesel ECM failure, and what you can do if your ECM is failing - or fails.

1. Moisture Causes Corrosion

A diesel ECM is a finely-tuned bit of equipment which relies on delicate microprocessors to do its job.

If other parts of the car are being corroded by the elements, the rust and corrosion damage can spread into the ECM too. Moisture might also creep into the unit, which can fry capacitors and cause the whole system to seize up.

Either of these things can kill the microprocessors outright if they're not solved right away.

Sometimes, the underlying cause is that the seals on the ECM have broken down over time. Gradual wear and tear can eat into these, creating an access point for moisture.

Checking the seals every six months or so will give you an early warning that something is amiss. You can reseal the unit yourself using silicone on the lid. Be careful if you do this - silicone which spills onto the processor could cause damage, and will not be easy to remove.

If you're not confident doing this yourself, call up a professional. Or if the unit is already beyond saving, it's time for a new ECM.

It's also a good idea to get under the bonnet at least once a year to inspect for corrosion.

If there's corrosion on any components, there's a good chance that could spread throughout your car's other systems. Save yourself a packet by replacing them then and there, rather than waiting for rust to creep across the whole thing.

2. Is Your ECM Grounded Properly?

'Grounding' or 'earthing' is a term in electronics that refers to the provision of a path for electricity to flow to if there's a short circuit or spike in voltage.

This protects people from a nasty shock in the case of overload. But it also protects the diesel ECM itself from excess current, which could cause enough damage to blow transistors and ruin the system.

This might be the result of damaged ground wires. Perhaps these have been damaged by corrosion over time, or by a physical accident involving your vehicle.

If your diesel ECM isn't grounded properly and there's a short circuit, it could blow the whole unit. Short circuits might be the result of a damaged seal allowing moisture or debris inside the shell.

It could only take a small piece of contaminant material lying across two contact points to cause a short circuit. This isn't completely unforeseeable if your unit is damaged.

Think of the grounding as a backstop to prevent further damage. Always make sure it's wired correctly at both ends - a ground wire that runs from the ECU but is flapping in the breeze at the other end is not a lot of help!

You should take note that there's no point replacing a diesel ECM if the short circuit hasn't been fixed. You're just exposing a brand new unit to the same problem, which could result in a very short lifespan and a lot of wasted cash.

3. A Dying Battery

Dead cells in your battery can cause the ECM to splutter and choke. This is because of varying voltage issues. That's a problem which will be compounded if those grounding wires aren't in place in the right way (see above).

Some ECMs also have their own small battery on board which powers the memory function. If this wears out, the ECM will soon need to be replaced.

Conversely, problems with your ECM can drain the battery at record speed. This can happen even when the engine isn't running. Short circuits in the ECM's power relay are one of the most common reasons behind this niggle.

You should always look to replace your battery every four to five years. They don't stay reliable forever, even with the best of care.

However, if a brand new battery seems to be experiencing charging issues, or you leave your vehicle alone overnight and wake up to a dead battery, the ECM could be the culprit.

new ECM may solve the problem, but it might be a good idea to swap out the battery at the same time. This will ensure that the issue is resolved from both sides of this tricky equation.

4. Jump Starts and Other Jolts

Your diesel ECM loves the right kind of electricity.

It doesn't love being jump-started along with your engine.

When the cables are in the wrong place, you're driving high current through the ECM, which can burn out its fragile components. This can also cause other issues under the bonnet. Always make sure the cables are attached in the right places before jumping.

It's also worth mentioning at this point that careless welding can be behind some failures. This can cause a similar type of 'hot' damage to a diesel ECM as a burst of electrical current might. Since the circuitry is housed in a shell, it's not always obvious that welding has caused damage.

Have you had recent work done on your vehicle which involved a spot of arc welding? If you notice that performance has become quite odd, check your ECM out.

In less likely circumstances, lightning strikes can fry your diesel ECM too. Hopefully, you're able to put your vehicle in a garage during storms, which will protect against this risk.

Don't worry too much about this one though. A lightning strike will probably never hit your car - but there's not much you can do if it does. It's a good idea to make sure your insurance policy covers your car against this type of freak event.

5. Fuel Solenoid Problems

The fuel solenoid is found on top of your fuel pump. A 'solenoid' is an electromagnet.

The solenoid operates a valve to push fuel through the car from the fuel tank to the engine. It does this using degrees of pressure to draw diesel fuel down the line, without mechanical aid.

This means the valve must be in peak condition, or the pressure differentials can fail and the engine doesn't receive enough fuel to run properly. The diesel ECM in your vehicle sends signals to optimize the performance of the valve.

Corrosion of the solenoid can cause a short circuit in your ECM. This isn't an uncommon problem, as it's a part that's in constant use when the engine is running.

The same thing can happen if the wiring between your ECM and the fuel solenoid becomes damaged.

A replacement fuel solenoid at the right time could prevent the need for a full replacement of your diesel ECM.

6. Stress Causes Cracks

The stress exerted on a diesel ECM can cause hairline cracks to appear in the circuit board.

This can be caused by vibrations. If you regularly drive over rough terrain in a tractor or truck, for example, this problem is more likely to affect you.

Fortunately, many cracks like these can be repaired, though it's a fiddly job best left to the pros. It's a hard task to take on at home without specialist equipment.

You need to catch cracks in time though. Ultimately, stress can be responsible for loose and broken connections in the electronics. This could mean signals for engine optimization simply aren't getting through to the rest of the system.

When this happens, you'll notice performance issues and a lack of responsiveness from the engine while driving.

7. Old Age

No part lasts forever. Though you may wish otherwise, that's the central mantra of car maintenance.

A diesel ECM can last for a long time if you take good care of it (and your vehicle).

But nothing lasts forever. One day, you'll see that 'check engine' light tick on as your ECM ticks off for the last time.

You'll want a new one as soon as possible, as a dead ECM can cause your engine to act very strangely. This can even put additional strain on it, leading to other parts wearing out too fast.

The ECM is a vital part of the full system - so don't forget to get it replaced when it wears out.

The Importance of Maintenance

Time might be a great healer, but unfortunately, its blessings won't fall on your diesel ECM. Only a regular and comprehensive maintenance routine is going to give your ECM the longest life possible.

We suggest that you take the time at least twice a year to get down and dirty under the hood, paying close attention to the condition of your diesel ECM.

You should also take it for a professional service once a year, or every 10,000 to 12,000 miles you drive.

Getting problems to the shop as soon as possible means that there's more chance they can be fixed. Carrying on driving while there's something wrong can only make things worse, not better.

Of course, everything has a limited lifespan. The ECM is essentially a computer, and as all of us will know, things go wrong from time to time. Components break and need replacing - and sometimes, the whole thing just burns out.

Finding Problems Without Lifting the Hood

Although maintenance is vital - and we can't stress that enough - there are other ways to spot issues with your ECM.

This doesn't excuse you from your routine maintenance regime! Sorry, but we're hard taskmasters.

If the 'check engine' light comes on, or your engine is misfiring, these can both be signs of a problem with your diesel ECM.

It's also possible that an issue with the ECM is stopping the vehicle from starting altogether. Or you might suddenly lose power or find that fuel efficiency is not what it used to be.

These issues can be related to other parts, like the transmission box or even the engine itself.

However, if you've noticed that your diesel isn't running quite as it used to, it's worth checking out the ECM unit at the same time. Or ask a pro check it for you if you're still not sure what's wrong.

Help - I Need a New Diesel ECM!

If your diesel ECM is beyond repair, it's time for a new unit.

ECMs are built to fit certain brands of vehicle. Browse our range to find a unit that'll suit your needs, and get revved up with excitement for delivery day.

We also offer a rebuild service for existing units, which come with a complimentary one-year warranty for your peace of mind.

Please remember to supply all the information we ask for during checkout. This will help us with our programming and calibration procedures. We want you to end up with the best results from your new ECM.

We also realize that ECMs aren't the most straightforward subject for many vehicle owners. If you're unsure about how they work and what you're looking for, just get in touch.

Our knowledgeable and approachable team can point you in the right direction and will be happy to answer any questions you have about your new diesel ECM.

Posted On: 27/04/2018

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