2003 P5 PCM failure?

C

cspcrx

Member
I have a 2003 P5 and Friday the charging system started acting up. Wasnt getting any measurable output from the alternator. Took it to the dealer, since that was under warrenty from being replaced in November. Now they are saying they replaced the alternator and its still not working and that the PCM may be bad. They are telling me the voltage regulator is in the PCM/ECU and if thats bad it must be replaced. $1200 part OUCH!!!!
Anyone heard of this on these cars. Every car I have worked with had the regulator in the alternator. Just doesnt make sense.
Thanks all.
 
True. It is in the ECU.

BUy a used ECU (or borrow to make sure that is the problem). It is super easy to remove and replace (under the passenger floor board).

None have failed that i am aware of - so i would really troubleshoot further before buying one.
 
The dealer has it out now. I was there late Saturday afternoon and they pulled it out. They didnt know what to do next. Wanted to wait until today to see what Mazda says and their Master Tech is in.
Figures I am first. LOL
I think I am doomed to not be happy with Mazdas. My first Mazda back in the day was an 80 RX7 and the ECU went out in that too. ARG!
 
If that's the case and you're N/A, then you should talk to SpicyMSP. He has the equipment to re-flash ecu's with the stock or more importantly, they MP3 ecu programming to give you a more linear power curve. He's selling for 250, then you send him back your ecu and he gives you back 100 for a grand total of 150. Look into it.
 
dude, if the ECU is ****** up, no reprogramming will fix it!
think! if the electronics are jacked up, SOFTWARE changes won't do anything! it's just like your PC at home!
 
Oh I didn't know that. I thought if the ecu programming was damaged, then you could re-flash it as a repair.
 
At this point they are telling me the PCM is damaged. I am hoping to know for sure tomorrow what the exact problem is. I was just curious if anyone had seen this or heard of this before. Thanks all.
 
That really sucks to hear, man. If you want, I bought an MP3 ECU for my P5 and my stock P5 PCM is just sitting in my garage. I could ship it to you and you could see if it works? Then you could keep it for $75 if you want. I could even overnight it to you. But no pressure, I'm not trying to sound like a d-bag who just wants to sell an ECU.

I'm in the Cleveland, OH area if you want to pick it up or something.
 
el_Don said:
If that's the case and you're N/A, then you should talk to SpicyMSP. He has the equipment to re-flash ecu's with the stock or more importantly, they MP3 ecu programming to give you a more linear power curve. He's selling for 250, then you send him back your ecu and he gives you back 100 for a grand total of 150. Look into it.
Click to expand...

Follow this advise. Just don't return yours.

a mp3 ecu for 250$ is better than the crap the stealership is going to give youfor 1200$

And can you do me a huge favor and ask them if an aftermarket high-output alternator would work on your car or if the PCM would cause it to not work properly?

I need to know for my car and I'd appreciate it if you could ask for me, thanks!
 
Lewis I will let you know thank your for the offer. I am really hoping its not the PCM.

Social I will try and ask them. Based on the responses from the two techs working on it on Saturday I am not sure if they will know. they both told me they dont really work on Proteges and didnt even know where the PCM was. But I will give it a try.
 
wow. I gotta' bad feelin' about 'dese mazda shop clowns....

If you can (my advice) let the guy (above) overnight you his ECU and try it (i still don't think it will fix it). Way cheaper that letting the clowns work on it swapping parts and charging you as they go...

AND i have zero confidence a software reflash will fix an ECU that fails to regulate voltage (My $.02).

AND unless you have a manual transmission - you could not use the MP3 reflash anyhoo...

Good luck.
 
I have a feeling it may be to late at this point. Supposed to know something in the next couple of hours.

Mine is an auto so the upgraded ecu would not work.

Its basically a stock daily driver. Other then the K&N drop in filter & magna flow cat back system.

As you can see in my sig. I have another toy that gives me my need for speed.
 
....they ar ea mazda place and they have never worked on a protege? either thats good ass reliability or thay suck at their job. wait for the tech but u would to the ovcernight deal u got. probably ur best shot.

Maybe its the coding for that section in the ECU. is that a possability?
 
Dealer called. Their master tech, who had been out, looked at it and in 45min figured out the problem. Wire connector on the main wiring harness that goes to the fuse box is broken. Of course Mazda doesnt sell them they are part of the harness. So the tech is searching for something that will work or they may have to find a harness from a local junk yard. I tell you if its weird its going to happen to my car. ARG!
 
Well at least it shouldn't cost you $1200. Always gotta look on the bright side. The same thing happened to one of my Civics and it kept blowing a fuse, it was a wire in the main wiring harness shorting out.
 
buy a 22 gauge wire and run it whereever the burnt out wire goes. Problem solved? It doesn't have to go through the harness. As far as I know, harnesses are just to make wiring easier. You don't need a whole new harness, Just the burnt wire(s).

And i was just guessing with the 22 gauge, it might be smaller/bigger.
 
Ok so I got the car back on Monday. Here is what the problem is. There is a plug that goes to the alternator. One of the wires that is in this plug goes to the fuse box by the battery. Not sure if this is how the alternator knows battery voltage or what. Anyway the wire was broken just above the connector. This caused the alternator to see no voltage and go into charge mode constantly and basically fry the alternator, actually it fried two of them actually. So they pulled the harness out of the car. Luckely they were able to get the old connecter off so they could reuse it, otherwise I would to have had to get a new engine harness. The tech laughed because his guys were trying to make it so complicated and it was something very basic. I asked if the cars could handle higher output alter. The response was, I wouldnt do it unless you direct wired it and not go through the harness wires.
 
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