PCM Advice

[enterflux]

Hey guys, I'm back with more questions.

I brought my P5 in because my check engine light has been on with codes P0455 and P1250. My mechanic checked it out and found one more code that's appeared since I last checked. He tested around and told me that it's a problem with the PCM not grounding, because he could take a wire to each of the 3 solenoids associated with the listed codes and could manually ground them no problem. Unfortunately, the only place that can fix this problem in my area is the stealership.

I located and checked out my PCM this morning and I noticed this on the wiring:

Full size pic: http://i.imgur.com/R6skoEn.jpg

I also installed a subwoofer last summer, which required me jamming a fairly large power wire through the firewall in the tight enclosure the PCM wires run through, so I'm not sure if maybe that caused the problem?

So, here's my question: If you can tell from the above picture, does it look like the grounding problem could be because of that mess? Or is there a way that I can test to see if it's actually a wire problem and not the PCM? If it's the PCM, I'm going to just call around to some junkyards and try to find one instead of having to sell an organ to afford the dealership putting one in.

Thanks for your help!!

 

[tweety2300]

If you're not the one that taped it up, it's been tampered with before. Shouldn't be any tape there

dont drive it till it's fixed easily cause an electrical fire.

If you didn't tape it wiring has defiantly been messed with. Could have been cause by you're amp wire could have been cause by someone's bad wiring.2 ways to fix it, undo that mess and heat shrink every individual wire at all places and hope and pray that's the only section ****** up. Or do it the right way and just replace the entire harness. Fixing it is cheap but a lot of labor, not a problem if you do it yourself. New harness would take an hour or 2 to do

Ecu very rarely go bad. Even if it is bad it's still doing its job. Fix the wiring, pull the bulb out for cel and forget it ever happened

 

[enterflux]

Thanks Tweety. The only tampering that I know of that's happened to the car is that the previous owner put in a sunroof.

I did some further inspection tonight and that melted glob on the wiring in the picture was just melted electrical tape. I cleaned that off and untaped the main wiring to take a better look at splices. I'm not 100% sure of which splicing is factory work and which is after, but I've included pictures of what I found. In total, these were wires that were spliced:

a. 85(B, should be Y) & 86(G) - "CMP Sensor" http://i.imgur.com/2PAwMQq.jpg
b. 21(Y) & 22(O) - “RPM (Engine Speed)”
c. 6 (G/W) - “CPP (Clutch Switch)” http://i.imgur.com/mXQ62Ju.jpg
d. 91 (O) - “Sensor GND” -- This was spliced in blue tape and had +-6 orange wires all spliced into one orange wire that went to the harness. Call me crazy, but I e. don't think that's right. http://i.imgur.com/MLitxVu.jpg
e. 4 (G/W) - “B+ Monitor”
f. 55 (G/W) - “Back Up Power Supply”
g. 35 (B/Y) - “Catalytic Converter Efficiency”
h. 60 (B/P) - “HO2S (Front)”
both g & h: http://i.imgur.com/JaywgRD.jpg

EDIT: Here's what I referred to for the pinout. http://www.mazdaspd.com/manual_files/01-40b.pdf

 

[The_big_dill]

d. 91 (O) - “Sensor GND” -- This was spliced in blue tape and had +-6 orange wires all spliced into one orange wire that went to the harness. Call me crazy, but I e. don't think that's right. http://i.imgur.com/fhiko2s.jpg

Broken link.

Based on aftermarket ECU knowledge, sensor grounds share the same pin on the ECU.

I have to agree with Tweety on the ECU rarely going bad. One time I had a sensor issue on a different car and all tests concluded that the ECU was bad... Took it to an auto electric and all he did was replace a wire to the sensor and all was good.

 

[enterflux]

Sorry about the broken link. Ill try this weekend to track down all those ground wires and test them. Any idea what would be causing 3 of them to fail on me?