2003 monte carlo ss 3.8L

Code reader came back p300. Took it to a shop and they put diagnostic on it. Came back with the ecm computer causing the p300. Shop said when the passenger side burnt up that it possibly shorted out the ecm. When are guys getting your plug in play ecms at?

 

ECM isn't really a thing on these- its PCM (powertrain control module - runs both the engine and transmission) or ignition control module (controls spark functions).

When the passenger side what burned up?

Assuming you mean PCM, the junkyard would be your cheapest bet. May need to buy online to get the right year / engine if local junkyards are rare.

Another option would just be to buy an aftermarket tuned PCM and just pay the core charge ($50) if you're having a hard time finding one. They'll pull the right physical pcm off the shelf and flash it to your car (along with the performance improvements). ZZPerformance is one option.

Normally this would be the crazy expensive way to go ($200 with core), but as these cars get older, I've seen some silly prices on junkyard parts that used to be practically free. So if you're not finding anything less than $200 from a junkyard, I'd probably just go this route.

 

Shop said ecm was causing the multiple misfire. Bought car with passenger side fuse box burned fuses. Wasnt burned all the way though. Replaced fuse box with a used one. Shop said I could get a plug n play ecm for $200 by searching the serial number thats on the ecm. Engine light stays solid when idling and flashing when driving.

 

If you're ok spending $200, I'd probably just buy a pcm from zzp. 3800s are one of their few core markets, so you've got a lower chance of issues than some random place online that supports everything.

 

I don't how the pcm is bad?

Here's pic of burnt fuse box. Just burned the fuses and relays.

 

Sounds iffy to me too, but its impossible for us to refute it / prove otherwise when we didn't actually run the diagnostics.

 

I know, maybe theres something like relay or some thing that would give off a poof diagnostic reading to say its pcm? Shop said its common problem on these car for the pcm to go out. Also said they have colorado with the same problem.

 

If you think they diagnosed it incorrectly, you could always try taking it to another shop for a 2nd opinion. I wouldnt say anything about the first shop at all, and see if they come to the same conclusion.

The hard part with with P0300 is that there's probably 100 different potential causes - Id bet it has the largest diagnostic tree of any obd code. A faulty PCM is certainly one of the possible outcomes. While its not a common cause, it is a possible cause, so I'll refrain from saying they're wrong as they put the time into testing everything (presumably/hopefully) to come to that conclusion.

IMO "common" is an exaggeration. Ive directly owned and/or been responsible for maintenance on (immediate family) close to a dozen 3800 vehicles with over a million miles of combined use and have never had a PCM failure (although I have had an ICM failure).

But with that said, the occurrence rate isn't 0 either. Ive certainly seen people with failed pcms on the various forums through the years. As with any other piece of electronics,, the lifespan isn't limitless. You may have just been unlucky (if it was diagnosed correctly).

 

I see Bumpin' chimed in with some of my thoughts. Only time I ever saw a bad PCM, it was very concrete the PCM was to blame. A P0300 have a variety of issues. I would suspect a ICM before a PCM. IN the case of the burnt fuse panel, ensuring you don't have damaged wiring to blame.

As Bumpin' said, we have not done the diagnostics. A PCM is not impossible but my experience says it is not likely. If you have feelings this shop is not doing right, as Bumpin' said, go for a second opinion.

 

Wires werent damaged by the burnt fuse box. Just the plastic, relays, and fuses were toast. Car has 196k miles on it.