PCM shorting out

So I recently had a misfire issue… I tried everything I could to fix the issue.
Plugs, injectors, wires, coils
Finally I took it to a mechanic.
He came to the conclusion that the PCM is shorting out causing it to short a coil.

I’ve never heard of this and can’t find anything about it and it only gets worse.
The PCM is discontinued and everywhere I call can’t find one.
They all tell me my best bet is a junkyard.
I’m worried how specific something like that could be for my truck?
Also are the ECU and PCM the same thing?
Forgive me first time working on computers.

Does anyone know where I can find one?
Also how hard is the removal and installation?

Really sucks bought the truck last week and guy failed to mention this.
Only misfires 10% of the time and happened to not misfire while I was driving.
Thank you.

 

Do you understand what a Short is?? System voltage going direct to ground unless circuit protection opens wires will melt to the circuit opens or the truck is burning .

That sounds very strange ! If the ECU is shorted It would be causing fuses to open and the truck would crank but not start!

Just what codes are being tripped ??

If you can drive at all most likely it is not the ECM.

Now an intermittent open circuit from a poor connection or broken wire is possible.

ECM should always be replaced with the same part number .

There are Companies that rebuild ECM`s either on a exchange orhave yours rebuilt.

About the only thing that takes them out are voltage spikes and getting wet.

 

I would get a second opinion. Electrical shorts are short or are they aren’t - they don’t just happen 10% of the time.

Is it just one cylinder throwing a code? What other symptoms?

 

You say you 'tried' plugs, coils etc... not sure if that means you've replaced them, swapped them around or what but here's what I would do. I'd pull your EFI fuse so it won't start, crank it over and listen for any strange cadence in the compression of the cylinders as it turns over. If you're not sure what to listen for search youtube for 'listening for low compression'. If it sounds off then I would follow up with a leak down test. I would also 100% do a block test to rule out a head gasket from the git go.

 

yes ECU and PCM are the same thing, now to your problem. PCM's very rarely go bad on Tacomas by themselves. There is something else going on with your truck and I do not think it is the PCM for the following reason. The ignition system on your truck has what is called a lost/wasted spark ignition system. There are only 3 coils on your V6 motor and when any particular coil fires, it fires for 2 cylinders, the one that is on top dead center compression stroke and the other that is on the exhaust stroke, so, if a particular coil is not working it would affect 2 cylinders. I would get the codes and see what cylinder(s) are affected and narrow it down first.

 

The ECM failing is extremely uncommon (but not entirely unheard of). However, I would tend to agree with the others that I'd be looking for a second opinion. During your troubleshooting, did you or the mechanic inspect and clean the ground cables?

Are your new coils and wires OEM? What plugs did you get, and did you check the gaps on them? What injectors did you get?

When you installed the new coils, did you clean the connectors with contact cleaner, and let them fully dry before reconnecting them to the new coils?

So you bought the truck a week ago, and you've already thrown new coils, injectors, plugs, and wires at it? Do you have your own code reader?

 

Yes I know this sounds super strange. It did to me as well.
I know next to nothing about shorts or anything electrical for that matter.
I have replaced all the things I mentioned. The mechanic (comes highly recommended in town for engines) says he’s sure that’s what it is and traced it all the way back to it.
I have my own code reader and as far as I could tell it was only throwing a code for cylinder one (very old code reader)
He said he’s positive that it’s my PCM and I have one ordered through a company for 190$

I really don’t know what to think after reading all the responses here.
I was hopeful he was right and that the PCM will fix it but now I’m not so sure.
As for head gasket, I have no symptoms (other then misfire) and he specifically said that’s not the problem.
Maybe I should take it in tomorrow to another guy?

 

If you already have a ECM on order I would just wait until it arrives, install it and see what happens. The ECM is located behind the glove box if you haven't figured that out yet. It is very possible that your misfire is caused by the bad ECM. Myself and another user just went through weeks of trying to troubleshoot why our trucks were hesitating and stalling out. ECM fixed both of our issues. Bad ECM usually causes other weird things to happy such as the OBD2 port not wanting to work correctly. The other user also mentioned his AC condenser was not working right and the ECM also fixed the AC. So look for other weird gremlins and electrical issues that may indicate a problem with the ECM.

 

That’s interesting about the other electrical problems! I’ll keep an eye on that for sure.
Thanks!

 

It is odd to me that it only happens 10% of the time... If it was the ECM would it be happening all the time?

 

One would assume so but who knows? When I first started trying to fix my 97' Taco it let me connect an OBD2 scanner once, but said there were no trouble codes, while I was staring at a check engine light. Never got a scanner to connect again until the ECM was replaced, so who knows.

 

Did the ecm fix your problems? I took my 97 computer to a local company. It had a miss at some rpm's and poor fuel economy. Plus other stuff. But it ran. Got it back and it melted down.

 

I never got my original ECM back from a local repair shop yet. I bought a rebuilt one from ProBuild on eBay for 1524 with tax. It's been in one day and it's working very well. I'll repost with fuel economy.

 

Dec 2021 was his last time here. Thinking you're not likely to get a reply