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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Pontiac Technician
Category: Pontiac
Satisfied Customers: 2373
Experience:  GM Grand Master Technician 2007. 14 years experience.
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The car has a problem that is really dangerous. Ocassionally

Customer Question

The car has a problem that is really dangerous. Ocassionally it wont start when I turn the key. After I wait a few minutes, leaving the key in the on position, I hear the fuel pump turn on and then I can start the car. That is a pain but not the scary part. I have been driving on the highway or just around town and the car dies. It must be a problem with wiring. I just got the ignition switch replaced and they also cleaned up a ground wire connection. But I am still having the problem.
JA: Can you turn the steering wheel at all? And what about the key? Is it worn or damaged?
Customer: There is not problem with the key and the steering is fine. Obviously when the car dies I lose the power steering.
JA: What is the model/year of your Pontiac?
Customer: 2007 Pontiac Grand Prix It happened again this morning on my way to work on a 6 lane highway I had to get over into the burm and sit there for 10 minutes and then it started up again
JA: Are you fixing your Grand Prix yourself? What have you tried so far?
Customer: I have a mechanic. No I would not do this myself It has been towed to the same garage 3 times All three times it was a difficult issue to diagnose They replaced the starter and the ignition switch I has to be something in the wiring
JA: Anything else you want the mechanic to know before I connect you?
Customer: Yes, I assume this is something that other people have a problem with. It has to be related to the PK3 Anti Theft system because when you turn the key the first two clicks everything powers up but when you turn the final springloaded turn to start it kills all power and nothing happens. Then when you leave the key in that on position like I said it resets or something because you hear the fuel pump turn on. That is an inconvenience but when it kills the car while I am driving 70 miles per hour it is dangerous. I shift to neutral and coast and get off the road
Submitted: 1 month ago.
Category: Pontiac
Expert:  david craig replied 1 month ago.

Hi Im David, thanks for visiting the site. pull the fuel pump relay, check for B+ on 30 then turn the key on and check for switch ign voltage on 86. let me know if you have both. the voltage on 86 should happen immediately as you turn the key to the run(not start) position.

Expert:  david craig replied 1 month ago.

do you still need assistance?

Customer: replied 1 month ago.
I need assistance. My car died twice on my way home tonight from work. The car shuts down and I coast to a stop on the side of the road. Turn the key off and then back on and wait about ten minutes. The check engine light turns on and I am able to start the car. If I can't get this figured out I am probably going to get crushed in an accident. My commute is over an hour and tonight it shut down after I drove about 5 minutes. Then after it started back up I drove another 5 minutes and it cut out again. Then it started back up and I drove over an hour with no issue. My mechanic replaced the start and then the ignition switch. It seems to me that there is a=some problem with either a worn and exposed wire that is shorting things out or a bad module or something else related to the computer that controls the PK3 anti theft security system. It is definitely part of the security system. When it wont start I turn the key and everything lights up and then I turn the key the final spring loaded click and everything goes dark. And this problem is occasionally when I go to the car in the morning and try to start it to go to work. I am sure based on the searches I have done on the internet that this is not a problem unique to me. If there is a way to bypass or remove the anti theft security feature that would probably fix the issue.
Expert:  david craig replied 1 month ago.

its not a security issue. once the immobilizer engages, it doesnt just reengage ....have you had the recall done with the ignition switch replacement?

Customer: replied 1 month ago.
I had the recall done. The dealer did not replace the ignition switch. They just put some things on the keys and added a link to the key ring. They also told me to keep other stuff of the key chain.My mechanic replaced the ignition switch. He also previously replaced the starter. And he found a corroded ground wire that he cleaned up.When it wont start and I am sitting there with the key in the on position the check engine light comes on at the same time that I hear the fuel pump turn on. And that's how I know I can start the car.The part of it shutting down while I am driving is more recent. It has been happening for the last few weeks. The other part of it not starting has been going on for several months.I assume there is a worn wire or a exposed wire or something that is causing this. I assume that because if it was a module or the computer, I would not think it would ever start.
Expert:  david craig replied 1 month ago.

ok, if you have a meter i can pull some prints of crtical circuits and we can check for shorts to ground or open wires. or while the engine is running you can start moving wire harnesses and connectors around to see if you can get it to stall or hiccup. let me know //

Customer: replied 1 month ago.
On line I saw that it could possibly be a crank sensor. I was not sure if that made any sense. Thought maybe if the sensor stopped working sporadically then the car might shut down for safety reasons? But the car runs really well when it is going down the road. Not missing and it is not having a rough idle either. Just shuts off while going down the road. I say that because if is not like a coughing sputtering stall, the engine justs shuts down or sometimes when I get in to go somewhere I have the no crank no start problem. With that it is normal for the first two clicks of turning the key and then it is a complete shut down when you go to the final click of the key, all power goes off and I have to wait roughly ten minutes for it to reset or something. I am not a mechanic and the testing of the connects and using the meter sounds great but I would need some help. I think the mechanic I use up the street has put the car on the computer to try and diagnose it and he has talked to the local chevy dealer about it too. I guess he is going to need to go through all of the wiring to try to find out where the problem is. Do you agree that it is probably a problem with a wire / connection or is it possible that a relay or fuse could cause this. I jsu don't see how a relay or fuse could be the problem. I mean they either work or they don't. This is working some and not working other times.
Expert:  david craig replied 1 month ago.

normally a faulty or weak crank sensor will not shut the car down while driving, but will not allow it to start after its been running fora while. like going to the store, coming back out while the engine is still warm and it wont start. letting it cool down then it starts. thats classic crank sensor failure.

Customer: replied 1 month ago.
That is definitely not the problem
Expert:  david craig replied 1 month ago.

then i would star looking for wiring harnesses chaffing against the engine or loose ground wires.

Customer: replied 1 month ago.
Thanks
Expert:  david craig replied 1 month ago.

you bet

Expert:  david craig replied 1 month ago.

any update?

Expert:  david craig replied 1 month ago.

do you still need assistance?

Expert:  david craig replied 1 month ago.

checking in to see how its going?

Customer: replied 1 month ago.
The mechanic has been going through all of the connections for grounds. He checked and the system was causing the security system module to lose it's power / programming and that was causing it to kill power and shut off the fuel pump. I hope that they can find the problem in the wiring and fix it. It also seems related to weather. Car died while driving in the rain and car would not start in the morning when it was cold outside, there was frost on the windows. The night before when I drove it and parked it there were no issues. That night after it was a warm dry day the car started right up.

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