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04 no crank no start. big headache

J

johnny t

New member
My son's 04 Grand Prix has the old no crank, no start issue. Occassionally it will start after sitting a while, run a couple days then leave you stranded by not starting. Eventually it will start and we get her home.
  • test battery = ok
  • No power on purple signal wire with key held in start position
  • Fuel pump primes when turning key on, all gauges and lights work.
  • Jumped crank relay turns over fine = starter ok
  • changed out ignition switch = no change
  • changed out ignition lock with different pk3 = no change although it did start without rprogramming security
  • neutral safety switch ruled out early on
  • We found a different BCM with same serial number tried that, again it ran then died couple days later.

We are stumped I've talked to several mechanics and they all said pk3 was bad, we changed that still nothing.
It is a NA basic gt if that means anything.
there is no security light flashing or staying on as a matter of fact it doesn't blink when hitting the lock on the fob.
We have become rather proficient at tearing the dash apart and swapping relays. All fuses checked out ok also.
 


Arlington.
Since last post car has died again. Now the fuel pump doesn't even cycle when ignition is initially turned on. right before this it was stalling while driving. As if things couldn't begin to get any worse. A wire tracing we will go.
 
So turn key on run, try to crank it and observe security light/indicator. If flashing you have passkey issues. If you can scan the computer look for a crank command.. might point to issue.
 
Check to see if you have fuel pressure by taking off the cap on the front of the motor and pressing the center valve (looks like a tire valve stem). Use caution as fuel should spurt out a little (do at your own risk). If there is sufficient pressure already in the system, the pump won't kick on every time you turn the key on. Can you have someone with a fuel pressure gage check what PSI you have while cranking? Mine was at 20 PSI and now with new pump I have 57-58 PSI. Actually, my car still stalled and did some weird stuff after changing the fuel pump. Ended up being the MAP sensor.
 
Thanks for all the insight fellas. As of a week ago I got this problem resolved hopefully. I haven't posted because I was waiting to see if it was fixed. I ended up going back into the underhood fuseblock to check fuses. I had my son turn key on and I started with fuse number 15 "pcm power", As soon as I grabbed it to remove I heard a bunch of relays clicking and the fuel pump cycled. So I wiggled it some more and heard the same thing. Bad fuse connection. I held it where it made good connection and everything worked and I told him to try starting it and it swung over and started. I got into the fuse terminal with a pick and fixed it and it has been running fine since. After this my son noted how much better his car idled. He said it was idling real low wanting to stall all the time at stop signs leading up to this whole no start no crank issue. Now it idles at 1400 cold and 900 warm. Knock on wood it's resolved I hope. Hopefully this is something that can help someone else down the road.
Thanks Again!!
 


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