7.3 Power Stroke PCM Failure Symptoms and Dealing with the Problem

Modern cars come with some form of computerization. An example of a computerized component in modern vehicles is the Powertrain Control Module (PCM). The PCM controls the transmission and the engine of your vehicle. It receives data from different sensors in your car and keeps it in operational mode. Therefore, your automobile cannot function efficiently with a broken or failing PCM. 

Key features and my opinion about the engine

• Production years:1994-2003
• Average lifespan of 7.3 Power Stroke:380,000-450,000 miles
• Fuel supply type:direct injection
• Power range:250-275 hp
• Fuel efficiency:bad
• Engine block material:cast iron
• Engine reliability score:high
• The most common problems:electronics problems, wiring issues, pretty bad fuel economy.

Symptoms of a Faulty 7.3 Power Stroke PCM

The PCM uses information from your vehicle's sensors to control its ignition system, fuel consumption, time to fire spark plugs, fuel-air ratio, automatic transmission, and other components of your machine. Therefore, any misbehavior in your engine, power system, emission, gear shifts, error codes, and gas mileage may indicate a bad PCM. If these systems start acting up, there might be damage to your car's PCM. But it could also mean an issue with your car's hardware. 

Hence, let's explore the signs of PCM failure to differentiate PCM failure from hardware issues. 

• Ignition Troubles

For the engine to ignite your vehicle, the PCM should operate normally. The PCM synchronizes ignition timing. If a fault in your PCM causes unsynchronized timing, the spark plug may fail to ignite as it should. Therefore, resulting in ignition troubles.

The PCM-related ignition troubles may worsen during the cold season. 

Remember, ignition problems may stem from unrelated issues, such as low voltage, bad battery, or unsynchronized fuel injection. You'll need a comprehensive diagnosis before narrowing it down to a damaged PCM. 

Check the fuel-air ratio, engine timing, and wiring before blaming a faulty PCM. A faulty ECU (Engine Control Unit) can cause ignition problems if there is no fault in your vehicle's fuel-air ratio or wiring. If the ECU fails, the engine doesn't get the data it needs to ignite the car. The poor data input may require several attempts before the engine revs and ignites the vehicle.   

• Lights and Error Codes on the Dashboards 

A faulty PCM will activate the lights and error codes on your dashboard. The warning light could be directly related to the PCM modules if you see the "Check Engine" warning on the dashboard.  

A "Check Engine" light can also mean a loose-fitting gas cap, damaged or worn-out spark plugs, a damaged catalytic converter, or a clogged or damaged mass air flow sensor. 

Let your mechanic reset the error code to ensure it's not a false alarm. Once the mechanic resets the "Check Engine" warning, they will diagnose the engine to check the source of the error code. The PCM could be the issue if everything else in the engine looks intact.

You might also see different error codes like U0100, P0606 code, or P0603 code. Other symptoms like trouble starting the car, poor fuel economy, and reduced engine performance may accompany the error codes. All these problems can be directly linked to a damaged PCM since it controls multiple systems in your automobile. The P0603 error code communicates a failure in your car's PCM. The error code shows that the PCM has failed its own KAM (Keep Alive Memory) self-test.

• Engine Stalls

The PCM oversees multiple engine operations. Therefore, a failing PCM may cause engine stalls or stutters. It could also mean a mechanical problem in your engine. Check the engine hardware before narrowing it down to your vehicle's computer system. 

If the hardware functions as expected, the setback could be from your PCM or ECM (Engine Control Module). If you observe a mishap with the fuel settings or engine timing, it could be due to a faulty ECM.

A damaged PCM, on the other hand, causes performance issues. You'll notice poor engine performance, acceleration problems, and bad fuel economy. The hitch could also manifest as random shifts and transmission problems.

• Increased Emissions

If you recently performed an emission test but failed, there is a high chance you are driving a vehicle with a faulty PCM. The engine module, a part of the PCM, monitors your vehicle's fuel-air ratio. Your car needs to operate on a balanced fuel-air ratio. If there is a failure in the engine module, it causes fuel consumption and emission inefficiencies. 

For example, if the mixture lacks air, it will result in incomplete combustion. The incomplete combustion, in turn, results in excessive carbon monoxide emissions. It also leads to the emission of other uncombusted compounds. 

Increased emission could also be a symptom of a damaged catalytic converter. Therefore, a comprehensive diagnosis will tell whether it's a faulty catalytic converter, an oil leak, or a problem with the PCM's engine module. 

• Bad Gas Mileage

Have you noticed a sudden loss in your car's gas mileage? A faulty PCM causes random shifting and a bunch of other transmission issues. When a car's transmission and gear misbehave, so does its gas mileage. Any gear issue causes a loss in a car's gas mileage hence the sudden loss in your car's gas mileage. 

A faulty ECM could also cause a loss in gas mileage because of an inefficient combustion pattern which harms the car's fuel economy. Monitor the car's fuel consumption. If it doesn't improve, have a mechanic assess the car's PCM.

• Voltage Overload

In most cases, problems stemming from a damaged PCM are due to exposure to high voltage in the car's electrical system. While the PCM has a protection mechanic that safeguards it from voltage spikes, it cannot survive prolonged exposure to voltage overload. 

But a thorough diagnosis will help you establish whether the voltage overload is due to a damaged PCM. 

• Random Shifting

A PCM facilitates automatic shifting, a primary feature in most modern cars. So, if your PCM has an issue, you may notice random shifts. The unsystematic transmission may result from a faulty sensor, improper communication between the gears and the control unit, or damaged circuits in the PCM. 

Also, an imbalanced fuel-air ratio may cause random gear shifts. The PCM monitors and balances the fuel-air ratio. The information relating to the ratio tells the gears when to shift. Therefore a faulty PCM or fuel-air ratio may cause random shifts. 

Ignoring random shifts can be dangerous. It may cause your car to remain stuck in a particular gear. It can also cause severe transmission failure. 

How To Diagnose and Fix a Faulty 7.3 Powerstroke PCM

Before taking any replacement or repair steps, you'll need to assess the PCM visually. You can find the PCM in your car's engine bay. 

You'll need a screwdriver, flashlight, an OBD code scanner, and a multimeter to perform the diagnosis. Before checking it, ensure to connect your battery to the PCM. Also, check if there is any sign of rust, loose wires, or corrosion. If you see any rust or corrosion, you may need to replace the PCM. Reconnect any loose-fitting wire. 

While still in the engine bay, check whether the engine has a full charge. Use the multimeter. You should see 12.6v and above if it's off or 13.7v if the engine is running. If you get a lower figure, retest the battery. Low voltage may cause sensor failure. We need to cross the low voltage of the list to ensure we don't miss a faulty PCM. 

If your battery has enough voltage and shows no signs of rust or corrosion, plug the OBD scanner. Check whether your car's PCM produces OBD error codes. You can easily access an OBD code manual online. Check for PCM-related error codes. If you see any error codes, assess the wiring and sensors to check if they're functional. Visually inspect the wires and keep checking them with the multimeter. Connect any loose wires and replace any failed parts. Reset your car's codes and drive it over a short distance before rescanning. 

Leave PCM repairs to your mechanic. The process needs specialized tools. 

Does It Cost Much to Fix or Replace a Faulty 7.3 Power Stroke PCM?

The PCM allows communication between sensors and other car components. Hence, it is a very vital system that controls the engine and transmission. Therefore, you'll have to scoop a significant amount from your savings to get a PCM replacement. You'll have to spend up to $1500 to replace a faulty 7.3 Power Stroke PCM. But the cost may go up or down depending on your mechanic. 

Last Thoughts

It's advisable to quickly repair a faulty PCM as soon as you notice any issue with it. The symptoms and the error codes discussed above can help you assess whether you need a further PCM diagnosis or not. If you ignore these symptoms, the problems may progress and damage the whole PCM unit. Run a routine PCM diagnostic to keep checking the operational health of your PCM.