Quick Answer: Will A Bad PCM Throw A Code?

Can I use a junkyard PCM?

It wouldn’t run for more than two seconds.

I took it all to the dealer and paid $84, and haven’t had a problem for 2,000 miles now.

Shifts fine, fuel pump primes, engine light is off, it’s all good.

The short answer in my experience is: no, you can not plug a junkyard PCM in without flashing it to your VIN..

How do I know if my ECM relay is bad?

Symptoms of a Bad or Failing ECM-Power RelayNo power when the key is inserted. One of the first symptoms of a problem with the ECM power relay is no power when the key is inserted. … Engine will not start. Another common symptom of a problem with the ECM power relay is an engine that will not start or turn over. … Battery drain or dead battery.

Does the PCM control the fuel pump?

The are two main components that make most fuel pumps run: the PCM (Powertrain Control Module) and the fuel pump relay. … The fuel pump relay is controlled by the PCM by providing the relay with a ground. The PCM chooses to turn the relay on when it sees the motor is running.

Can you test a PCM?

You need to check the sensors that are connected to your PCM, as well as the wires that connect them. If you’re seeing a PCM code – or two, or three – it can really help you narrow in on which sensors or wires are faulty. Perform a visual inspection of these wires, as well as checking them with a multimeter.

What does flashing a PCM mean?

Powertrain Control Module reflashingPowertrain Control Module reflashing is essentially a software upgrade. PCMs are built with microchips that can be reprogrammed electronically without being removed from the vehicle. … You might hear the terms PCM programming, PCM reprogramming, PCM flash, or PCM reflash.

Is ECM and PCM the same thing?

PCM (Powertrain Control Module) – This is a combined engine and transmission control unit which will provide management and correct function of the engine and transmission from one control unit. ECU (Engine Control Unit) / ECM (Engine Control Module) – This is an electronic control unit that manages the engine only.

Will a car start with a bad PCM?

It is highly possible that symptoms of a bad PCM include the vehicle not running at all. All these components play a part in kicking off and running the engine. When they can’t function properly, the car may not run at all. In that case, the engine will not crank or even if it does, it will not start.

What causes PCM failure?

PCMs typically fail for one of two reasons: voltage overloads (often due to a short in a solenoid or actuator circuit) or environmental factors (corrosion, thermal stress or vibration). … If water gets inside a PCM, it can short circuits and set up irreversible corrosion that ruins electronic connections.

How do I know if I need to replace my PCM?

7 Common PCM Failure SymptomsYour ‘Check Engine’ Light is On. … Your Car Won’t Start or Starts Roughly. … Sudden Loss of Gas Mileage. … You Failed Your Emissions Test. … Your Engine Stutters or Stalls. … Erratic or Random Shifting. … You’re Receiving a PCM-Related Error Code. … What to Do If You Experience PCM Failure Symptoms.

How much does it cost to fix a PCM?

The PCM controls more than 100 factors in your car, and for that reason, is very important – and expensive. A typical pcm replacement cost comes to between $500 and $1,500 on average.

How do you reset the PCM?

How Can I Reset the PCM on My Car?Open the hood of the vehicle.Disconnect the negative battery cable from the battery. Use a wrench to loosen the lock nut, and pull the cable off. This cuts the power to the PCM. Wait for five minutes. Reconnect the negative battery cable to the battery and close the hood of the vehicle. The PCM is now reset.

What are the symptoms of a bad PCM?

Usually a bad or failing ECU will produce a few key symptoms that can alert the driver of a potential issue.Check Engine Light comes on. An illuminated Check Engine Light is one possible symptom of a problem with the ECU. … Engine stalling or misfiring. … Engine performance issues. … Car not starting.

How long does it take to replace PCM?

The process takes around about half an hour, but keep in mind that most auto-electricians charge you for at least one hour of work. PCM reprogramming is also one of the few times we’ll recommend a dealership over an independent mechanic.

Can a bad PCM cause transmission problems?

For example, poor performance or unexplained drops in fuel economy or efficiency are often related to onboard car computer problems, or faulty ECU issues. A damaged ECU can cause problems when shifting gears in an automatic transmission, or cause sudden jerking or stopping that’s similar to transmission problems.

How do you troubleshoot a PCM?

How to Troubleshoot the PCMLocate your vehicle’s PCM. … Look specifically at the wiring harness. … Locate your vehicle’s diagnostic data port. … Connect your OBD-II scanner to the diagnostic data port.Push your key into the vehicle’s ignition cylinder. … Watch the OBD-II device’s read-out screen for the codes.More items…