How To Bench Test A Pcm

How to Exam a PCM

Modern cars rely on computers to manage their various systems. For example, when was the last time yous or someone you know had to adjust their car's timing? Unless you're a classic car collector or you're old plenty to carry an AARP card, the answer is probably "never".

In that location's a reason for that; nosotros have computers to handle timing, air to fuel ratio, and fifty-fifty when and how our automatic transmissions shift. The advantage of this isn't just less maintenance. It also means y'all get better gas mileage and performance since computers can make adjustments on the fly to compensate for changes in temperature, humidity, and route conditions.

The disadvantage? Computers are a pain in the rear to diagnose. To assistance yous out, we've put together a handy guide.

What Are the Symptoms of a Faulty PCM?

Many of your auto's functions are controlled by the powertrain control module (PCM), which works in conjunction with the engine control module (ECM) and transmission command module (TCM) to adjust engine timing, the air to fuel ratio, and other systems.

So before we talk about how to exam a PCM, hither are some common symptoms of a PCM failure.

• Your "check engine" light is on
• Other alert lights may be on, including traction command and ABS
• You lose fuel economy for no apparent reason
• Your car stutters when starting, requires multiple attempts, or won't offset at all
• Stuttering or stalling during idling
• Your transmission sifts erratically, skips gears, or fails to shift at all
• Poor performance and acceleration

In that location are other things that could be causing these symptoms. For example, poorly-inflated tires tin can cause a drop in gas mileage, and difficult starting tin can be caused by a weak battery or failing starter. But if yous're experiencing ii or more symptoms with no other obvious crusade, it'southward a good idea to check your PCM.

What Tools Do I Need?

Earlier starting whatever chore, it'due south important to take the right tools for the task. Here's what you'll demand to examination a PCM:

• Flashlight
• Standard and Philips screwdriver
• OBD or OBD II lawmaking scanner (check with your car'due south manufacturer on device compatibility)
• Multimeter
• A new PCM (if replacing)

Step 1: Visual Inspection

Now, before you outset doing any surgery on your auto, the first matter to do is to cheque for rust or a disconnected wire. This isn't the nearly common crusade of a PCM failure, but it's the easiest to identify.

Make sure that your PCM is connected to your battery, and that in that location'due south no rust on the PCM itself or on the bombardment wiring. Reconnect any loose wires if necessary. If your PCM has experienced corrosion, you'll have to skip to stride 5 to see if it's failed.

Step 2: Check Your Battery

While you're under the hood, use your multimeter to ensure that your battery has a full charge. It should read at to the lowest degree 12.6 volts with the engine off, or 13.seven volts with the engine running. If it'southward showing less than that, fully charge your battery and re-test. The reason this is important is that low voltage can cause certain sensors to fail, depriving your PCM of the input it needs to make correct adjustments.

Step 3: Code Scanning

If your battery is fully charged and there'due south no visible rust, your side by side step will be to plug an OBD or OBD II code scanner into your vehicle and run into if the PCM is producing any OBD error codes. This can be incredibly helpful in solving many mechanical and electric issues since yous tin can utilize these codes to narrow down which systems are causing the failure.

A codebook (or easy Google access) is a necessity here since yous'll demand to learn what the codes hateful in order to make caput or tail of them. Nosotros've written about several PCM-related error codes in the past, including the P0603 code , the U0100 lawmaking , the P0113 code , and the P0606 code . Evidently, this isn't an exhaustive list, but information technology represents the about commonly-displayed error codes.

Step 4: Inspect Wiring and Sensors

Hopefully, y'all had some success with the previous step, because this is where things tin can get tricky. 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 ii, or three – it can actually help you lot narrow in on which sensors or wires are faulty.

Perform a visual inspection of these wires, every bit well as checking them with a multimeter. Don't forget to check ground wires and connexion points, either, since these are frequent causes of trouble.

Once y'all've replaced any failed components, reset your motorcar's codes, and bulldoze for a while. Most probable, you'll have solved the problem.

Step v: Try a Replacement

If all else fails, or to ostend some repairs, you may demand to try running your vehicle with a replacement PCM. Ensure that the PCM is the correct version not merely for your make and model, but for the same year likewise. If it turns out that your PCM was faulty, y'all'll immediately notice an improvement in functioning.

And that, friends, is how to test a PCM.

What if I Need to Replace My PCM?

If yous've followed all of these steps and information technology turns out that your PCM does demand to be repaired or replaced , information technology's a good idea to get professional help. While it's possible to repair or replace your own PCM, it requires specialized tools , which you may only need to use one time.

For more information on what SoloPCMs can exercise for you lot, contact us via our web form, or call us at 888-848-0144. Our technicians have decades of combined experience and are gear up to help with any issues you may have.

Source: https://www.solopcms.com/blog/how-to-test-a-pcm-complete-guide/

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