My sisters 95 protege 1.5l LX check engine light came on about a year ago and I used the method jumping TEN and GRN to figure out the code, which turned out to be the O2 sensor. Fast forward to now and the check engine light is back on again, problem is now when I jump TEN and GRN the check engine light is static with no flashing. She took it into a mechanic awhile back for a misfire issue which ended up being a faulty plug wire arcing into the head but I'm wondering if the voltage to ground was enough or for a prolonged enough period to fry the PCM. Anyone ever run into this issue before?

 

Maybe you are making this more complicated than it is.

What does the code say now?

Have you read this: https://www.mazdaforum.com/forum/maz...%E9g%E9-31136/

 

Thats just it, Jumping TEN and GRN no longer flashes the codes like it did before, I get a solid, non flashing CEL so I cant read the code(s) now.

 

this is a '95 and should have OBDII. You go to the parts store and let them read the codes for you with a scanner.

 

Is it OBD I, or OBD II? '95 was the crossover year for standardizing the OBD system, so it could be either.

 

then he must have OBDI
I believe in OBDI you can reset the computer by disconnecting the battery negative and stepping on the brake for a few seconds, just as you do in OBDII. Someone correct me if I am wrong. That is what I would do, then I would drive the vehicle until a warning returns. Then read the warning. For example: long, long, short, short, short = 10+10+1+1+1 = 23

you find the codes here:

1993-1995 Engine Controller Malfunction Codes

 

The car is late 94 build date, 95 m/y OBD 1 so I cant just plug my scanner in. I've wiped the codes at least 5 or 6 times now and each time the CEL comes back on it wont flash when you jump TEN and GRN, even after following the steps outlined in the fsm whereas before the same procedure worked fine the previous times I used it. I was just curious if anyone ran into this issue before and if there was a simple fix. I guess the next step is tracing out the how the diagnostic wiring works and jumping TEN and GRN at the PCM, that and testing the CEL wiring as well.

 

Unfortunately, this is out of my frame of knowledge.

Hopefully, someone else can help. And if you get it resolved, please report it here.

All the best!