Hi all been away for a bit until now. Ive got a problem with my 1.8 l 2000 mazda protege. It cranks but wont start ,had to get it towed home from work last sunday. I was working on my vent solenoid, as Ive had a few rusty evap lines that Ive had to fix, so I was checking it too, and by the way its new. I wasnt hearing it come on when i turned ignition on. so I tested wires and found I had 12 v but no grd.which I thought so I attached the wire to grd and I could then hear it work. I had the car running around 3pm and all was ok. I came back out at 7pm to go home and the car wouldnt start. I tried a few things and nothing worked so I got it towed home the next day. I decieded to check to see what codes if any I had will I tried 2 scanners that I know work and I cant connect to pcm. I checked all fuses and they are good. So I figured some sensor was maybe pulling down the voltage and caused the computer to shut down so I unplugged them all. I have a engine diagram so I started to check and I noticed that I somehow lost the ground to the main relay. I took apart the engine fuse block to see if something was cracked inside like a copper trace but all is ok. Ive pulled apart the main wiring harness and found some coroded connections that Ive since fixed. I have power to the pcm as per #4 pin to it. Ive checked all grd wires going to it 24,51,76,77,103 and they are all good. So today I put a separate wire to grd for the main relay and it comes on when i turn on key along with fuel pump but I still have no communiction with pcm. Im where I have to check to see if I have power to pcm from main relay at pins 71,97. Ill check to see if I have a broken or open wire. One note that vent solenoid Ive been driving with grd attached for awhile until I looked at drawing and saw that it goes back to pcm like a input to pcm so thats why I disconnected it... and its been fine so all of a sudden my PCM shuts down or is bad? By the way i thought I had a bad wire from connector over gas tank under seat hatch but Ive fixed it and it tests ok. Just wondering if anyone can shed some light on this. Im hoping to pcm is ok since when I got main relay to come on I hear the fuel pump pump gas to injectors. which comes from pcm I beleive as per drawing that I have thanks again.....to be continued..