7 SYMPTOMS OF A BAD PCM MODULE (ECM MODULE) -

This article will state some of the most common symptoms of a bad PCM module.

PCM stands for Powertrain Control Module and is the electronic brain of your car, so to speak.

Another common term for this car part is the ECU which means Electronic Control Module.

Whatever you call it, when it starts malfunctioning, it can cause an array of problems that are pretty hard to spot.

Hopefully, this article will help you notice the problem and distinguish it from other car problems.

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SYMPTOMS OF A BAD PCM MODULE

1. THE CAR CRANKS BUT WILL NOT START

A common symptom of a bad PCM module is that the car has a heavy start meaning it cranks a lot but barely manages to actually start.

This symptom much resembles problems with spark plugs or a clogged fuel filter for instance.

The heavy cranking appears occasionally at first, but in the later phases of the problem, it may not start at all.

2. POOR ENGINE PERFORMANCE

The next symptom is poor engine performance. This may show in the form of engine misfire, engine stalling, sudden loss of power, and else.

When the PCM malfunctions, it stops properly regulating vital engine parameters and may disrupt proper and timely fuel injection, air intake, ignition, and much more.

3. INCREASED FUEL CONSUMPTION

Due to poor engine performance, you’ll notice an increase in fuel consumption.

It will go up easily anywhere from 30 up to even 50 percent.

4. FREAK ELECTRONIC PROBLEMS

When the PCM starts seriously malfunctioning, you’ll notice random and freak electronic problems that sometimes seem as if the car is possessed.

If you pay more attention you can notice that a bad PCM module is the problem since a certain pattern usually appears.

The electric and electronic problems appear connected and intertwined. For instance, when you turn an appliance off, another appliance turns on or stops at the same time.

The problems may be harmless (more or less). For instance, the power windows or air conditioning may malfunction which is tolerable in most situations.

But it can also be more serious like the engine issues we’ve mentioned which affect the car’s mobility.

5. WARNING LIGHTS RANDOMLY APPEARING

Besides freak electronic problems, you’ll probably also see the warning lights appearing on the dash for seemingly no reason.

Only one light may appear, most commonly it’s the check engine light but they may also appear in clusters.

Usually, the warning lights appear randomly and again, in a certain pattern.

6. SHIFTING PROBLEMS

Worth mentioning is that a bad PCM module can cause problems with shifting on cars with automatic transmission although this is more rare.

Nevertheless, if you drive a car like this and notice a problem with shifting, it is worth checking.

7. THE OBD TOOL WILL NOT CONNECT

The final common symptom of a bad PCM module is that you can’t connect an OBD tool.

Although the connectors and connection are OK, everything seems fine, you’ll probably get a message on the tool that it’s unable to connect to the car’s PCM.

Know that with a bad PCM, this can happen at a moment’s notice.

One time the tool connects just fine and everything works, the next day you can’t connect at all and get an error message.

CONCLUSION

As previously mentioned, it’s hard to determine if the car’s PCM module is bad mainly because it can take a long time for it to malfunction completely.

Also, it mimics a myriad of other problems like sensor problems, faulty connections, intake problems, and much more.

In other words, you can experience lots of problems that can send you on a wild goose chase. A bad PCM is one of the hardest car problems to diagnose.

Everything may check out OK, even the diagnostic tool will find no problem. The next day the car won’t start at all.

I would recommend considering a bad PCM module problem when the car won’t start at all especially if you can’t connect an OBD tool.

In the end, if possible, determine if the PCM is the actual problem since repairing or buying a new one is very expensive in most cases.