PCM fuse continually blows

Good afternoon.

What is the fuse number?


There are several fuses that control power to the PCM.

Roy

Mini fuse # 8 PCM battery (10A).

Good afternoon.

That is battery control to the PCM. No other circuits that I see.

It is either a wire harness issue or the PCM itself. Unplug the PCM and see if it still blows.

Roy

I already took out PCM and battery from car. I have to get back to you about if fuse blows without PCM plugged in. Once I get battery put back in. Working on two Buick's right now.

Okay, keep us updated.

Roy

Okay, put new fuse in installed battery and it did not blow, So I guess it is the PCM then?

Sorry, I did forget to mention that the volt light comes on and stays on before and after fuse would blow and after I removed the PCM itself. I am having brain farts I guess sorry.

One issue at a time. the PCM controls the alternator as well.

Yes, you need to replace the PCM.

Roy

Thank you for your help with this issue, when I get the new PCM I will let you know how it all pans out. Thanks again

You are welcome.

Feel free to follow up with any other issues.

Roy

I'm having a similar issue only I keep blowing the PCM, BCM, U/H relay fuse every time i try to start it. But if i unplug one of the connections on my BCM box under the steering column it won't blow but I lose headlights and a few other things.

Good afternoon.

From what you described, the BCM has an internal short and needs to be replaced.

You need a new one, not a used one as it needs to be programmed to your VIN number to be sure all your options function.

If you give me your VIN number I can get the procedure and location for you.

Roy

Could there be an external short? I'm not at the car right now so I can't get the VIN.

If it was external it would still blow the fuse.

Let me know when you can on the VIN.

Roy

It blows the fuse when i plug it in.

I read that before.

We are back to the BCM again.

Roy

Hi,

Have you checked the plug itself to see if there are any pins touching that would cause a short? Also, take a look at the attached pic and let me know if I have the correct fuse that is blowing.

If I do and there is no damage to the pins in the connector, I want you to unbolt the BCM so it has no ground. If it still blows the fuse, the problem is in the wiring to it. If it doesn't, then chances are the BCM has an internal short.

Here are a few links you may find helpful:

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

https://www.2carpros.com/articles/how-to-use-a-test-light-circuit-tester

https://www.2carpros.com/articles/how-to-use-a-voltmeter

https://www.2carpros.com/articles/how-to-check-wiring

Let me know.

Joe

Yes, that is the right fuse. So your saying look at the plug itself to see if there are any pins touching?

I'm not sure what you mean by unbolt the BCM because what I think is the BCM is just hanging down right now. I'll take a picture.

This is what I unplugged to be able to start it:

Hi,

Yes, the plug itself has pins in it that can bend or become damaged and short. As far as the BCM, I don't think it should be hanging.

Let me know.
Joe

Okay, so the pins are not damaged.

What exactly do you mean by unbolt the BCM?

Previous question was would not go over 65, cleaned it and now sputters out when you step on gas. Code 31 .
When you unplug it it does not shut off. Should it?
New one does same thing . Do I have a ECM problem.
Can you supply me with voltages at connector?

Good evening,

Did it have a code prior to you cleaning the mass air flow sensor?

First, you cannot clean that sensor, The part that gets carboned up has carbon baked on the end. There is no cleaner to remove baked on carbon.

https://www.2carpros.com/articles/engine-stalls

I would suspect either fuel pressure or a cat converter issue. It may be clogged not allowing it to go any faster than 65.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Roy

Circuit Description
When a pillar (Vortex generating body) is placed in the path of a uniform flow, vortices called Karman-Vortex are generated downstream of the object. Using this principle, a vortex generator is placed inside the volume air flow meter. By measuring the frequency of the vortices generated, the engine control module can determine the volume of air flowing through the volume air flow meter. The vortices are detected by their exerted pressure on thin metal foil (mirror) surfaces and a light emitting element and light receptor (LED and photo transistor) positioned opposite the mirror which senses the vibrations in the mirror optically. The engine control module uses these signals mainly for calculation of the basic injection volume and the basic ignition advance angle.

Yes. You could have an issue with the ECM. The three possible causes of this code and your issue are the sensor, wiring, or the ECM. I supplied all the testing for this code so if you run through this you will find the cause.

I would not just replace the ECM as this is the most likely cause after the sensor but that is expensive if it turns out to be a wiring issue. You can find that out with this testing.

Let me know if you have questions. Thanks

The VIN you needed is 2G4WS52JOY1307770.

I would do basic diagnostics first before replacing parts that may not be bad.

You need around 60 pounds of fuel pressure for this engine.

Also, check the back pressure of the exhaust. You can get a back pressure gauge to test the back pressure. You remove the upstream O2 sensor and insert it. If you have more than 1.5 pounds, the cat is bad.

Do your basics first before replacing anything so you do not waste your money on unneeded parts.

Roy