Here's the story: First off I have a 04 Cobra, all it really has done to it is a solid swap and full exhaust, the previous owner had a smaller pulley on it but I had no way to verify that the tune was safe so I removed it for the time being and am now running a stock upper and lower. A couple of weeks ago the battery light came on, (I plugged my livewire in to see what the voltage was when cruising at it was like 10.5-11 volts) but the next day it was gone so I thought nothing of it. Well then on Friday I was on my way to a friends house and I thought I would get on it, so from 4th gear I stomped on it took it to like 6200 rpm and the car dies. The guages shut down and the motor just dies. It acted like I had no fuel, like the fuel pumps had gone. I coast for awhile, and try to drop it into gear since when I would turn the key it would just crank but would not fire, but no matter what the car would not start. Luckily enough I was going fast enough that I was able to coast to my friends house. When I got their we started looking around under the hood to see if any wires had come loose and we also checked the shrader valve to see if it had pressure behind it which it did. I then checked the underhood fuses and found that the 30 AMP maxi fuse for the PCM was blown, put a new fuse in and it blows instantly when the key is turned on. I mean no crank just turning the key forward. I pulled out my livewire to see if I could read any of the trouble codes from the PCM but it won't make a connection with the PCM. I am at a lose as to what to do. I was thinking that maybe since the battery voltage was so the alternator was trying to over compensate for the lack of charge and the voltage regulator went out causing the PCM fuse to blow. I was not for sure so I unhooked the battery for about a day and replaced the battery and fuses this morning, but the same thing happened. I turned the car over but it would not start and it blew the fuse again. I am so lost, someone please help me.
HELP!! PCM fuse blowing!!
- Thread starter srt4tocobra
- Start date
On both of you cylinder heads you have a connection for a ground wire make sure they are properly connected...This should resolve your issue..It happened to me several times after my motor swap.
blowing the fuse means you have a short to ground somewhere.. Look for wires rubbing somewhere... Torquing the engine might have broke wires or rub thru the insulation...
alright thanks guys i will look into that. it scared the hell out of me, thought i blew the damn thing up lol.
For me, it was the wiring harness leading from the center console down to the o2 sensors. It had come out of it's plastic body bolt on the side of the tranny and was touching a header...melting to it. Might check underneath especially around the headers.
I will check that out I will be looking on Thursday or Friday to figure out what it is, thanks everyone.
I bought from a lady that lived in South Bend she had it stored in Niles, Michigan, so kind of. Why do you ask?
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sounds like a bad ground...just get that a/f checked before you get on it...
Keep us updated. It sucks chasing wires.
I most definitviely will but I am thinking that it is more than likely one the wires coming off of the back of the head. Why would that blow just the pcm fuse though? I am confused why it wouldn't blow any other fuses
Any computer controlled sensor that dont have a seperate fuse would cause it to blow.. Also a low resistance circuit in a solenoid, relay, driver, or wire would cause it to blow too..
Hey everyone just wanted to give you guys an update. I took some advice and looked around my drivers side cylinder head at the noise suppressor that is on the back of it and found that the nut that holds it to the head had come out and it was dangling close to my exhaust, which of course had melted it. Unplugged that and it started right up. My question is do I have to have one of those plugged in?
Wow, that was lucky you found the source so quickly! Wiring gremlins can be VERY time consuming!
yes it keeps voltage spikes and EMI from coils, alternator, injectors from getting into other circuits and disrupting their performance.
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