1996 Ford Mustang Car wont start, fan comes on when key on

The car started and I drove it before I tested the connector on the dpfe sensor I had the key on and the light was off at that time while I was testing, but when I pulled the pin off of the connector I must have created a short somewhere and now the car wont start it cranks up but wont start and when I turn my key to ON position the cooling fan turns on where should I go for the problem now is it a blown fuse, or could it be a bad relay and how can I check a relay if its bad, Im basicly gettiung 12V to the cooling fan on this car right now so I know there has to be something between so that it distributes voltage equally everywhere else, now can a ford dealer refresh my pcm or if I get a used pcm from another 1996 ford mustang cobra like mine can I just plug it in?

I just noticed that when I disconnected the fan connector and I turn the key to the ON position the fuel pump doesnt upload, you know the noise that it always makes when you turn your key to ON position it makes the noise of starting or preloading before you actually crank up the engine with your key, but when I looked at the fuse under the hood which is a 20A it looks good and I was checking it with a ohm meter on 200ohms setting and it has passege as in it goes to zero when I touched the two metal prongs on the fuse itself, is there another fuse for a fuel pump under the hood of the car that is seperate from other fuse boxes and maybe its somewhere on the firewall or under car, also I have other cars at home here and when I looked at them under I see a mesh style ground wire going to the exhaust from chassie and engine block as well as transmition to chassie, my mustang doesnt have those underneeth is that a big deal, and can it cause different voltages to be send throughout the car if the engine block is not grounded with that wire to the chassie. By the way I really appreciate your help and troubleshooting suggestions, all I want for now is for this car to start like it did before I tested the sensor yesterday I was driving it and the only problem I was having was the check engine light and I obviously made a wrong choice by testing it again, hahaa.

Ok I did one more thing just to see what would happen I disconnected the big harnes wire under the hood of the car by the windshield the harnes had like 30 different wires going from al the sensors like tps and all the others and the harness had a bolt on it so when I disconnected that harness im guessing its the one that connects the PCM and put my key to the ON position my fuel pump started but was going constant now when I plug that harness back in as soon as I turn my key onto the ON position I can hear a lil shock under the hood so does that mean my Pcm is bad or is it a short somewhere, see when I created that short by testing one of my connectors im guessing could that shock the wire so now everytime I turn my key to ON it creates a shock so the PCM just shuts everything off, I was checking the dpfe connector to thebig harness connection for resistance and I got 3.69ohms in that wire or between those connections but when I touched another wire pin on that big harness connector I also got a negative ohm measurement so is that a short? And how can I find out how much resistance im suppose to get in that wire to make sure its good? That is the wire I was testing yesterday and thats the one that I created short with more likely when I heared a lil shock sound and all the sudden my cooling electric fan came on and thats when I couldnt restart my car, hope to hear some more suggestions I getting closer just not there yet and I definetly dont want to cut any wires yet if I dont have to

Ok yes I was doing all these tests but you know I got the car started and believe it or not I finally took my PCM out and it had a diablo sport performance chip on top of it but it was dock taped. Hahahha, I know its not suppose to be this way and there was also a ground wire on body itself next to the PCM so I took it off and cleaned it and when I pluged my PCM back into the harness and reconnected everything the car started but now its running rough when I floor it so im guessing a bad maf and ive noticed my injectors are 42lb and the maf is bigger aftermarket too so its not working properly and I was always careful by unplugging the battery when I was disconnecting the harness

I have 42# fuel injectors(green cap) and possibly a bigger size MAF Sensor without a supercharger, would that make more nox in the emission system and would bring the P1401 code on the car, some people told me that I just want to make sure because as soon as I took my DIABLO PREFORMANCE CHIP out of the PCM the car runs rough when I give it a full gas, is it because the diablo chip was telling computer that there were different injectors on car and different maf sensor and now that I took it off its working off of the default stock numbers and all, the code is still p1401 which is a high output voltage from the dpfe sensor can I just put a resistor in the signal wire and lower the voltage would that be one way I can fix that problm?

Yes I did replace my DPFE sensor and the enigne light still comes on with the same code P1401, well the injectors on a stock 1996 mustang cobra are 24lb injectors this one has 42lb injectors in my opinion this is a huge difference and much more fuel flow so my best guess on this is that the pcm still thinks I have 24lb injectors therefore there is an insificiant fuel/air ratio mixture right?The exhaust is modified I do have shorte headers and mac mufflers and an bassani x pipe in the middle with no cats but I do have eliminators on there, does my PCM is suppose to have any chips in it like where they had the performance chip is in am I suppose to have any factory chip in that place, right now I noticed if I put the performance chip in the PCM the car wont start so now I know for sure that the performance chip is bad.

I just never tought about that before because all mustangs ive had I always put offroad x or h pipe on it and that light never came up for me, but ok since the code says there is too much voltage or high voltage in the preassure side to the dpfe sensor then that means there is too much flow of anything specific in the exhaust or is it too much fuel or air, and I can instal the cats back on it if I really have to but even though I have the mil eliminators that will still come on, is there a way to check back preasure in the exhaust and see if I have possibly too much, that would probably give me a good head start on what to do next and what to fix on the car next right, I mean if I get the back preasure from the exhaust and its way higher then it suppose to be then im just going to get some catalyc converters and weld them in my x pipe no biggie if its really what this code saying and if it would bring it back to normal, I really appreciate your replies and hope you can still help me out on this P1401(Ford codde) issue, again big thanks, Martin