My 2001 buick century limited wont start but lights turn on.

[Mtilley_4]

So I've had the car for a year my dad got me it for my first car has little over 160,000 miles on it I have replaced the thermostat, water pump, starter, battery with bolts, did breaks and oil last week and this car keeps being annoying and not starting always when I try to leave work I turn the key everything lights up but the engine doesn't turn check engine light pops up everytime it does this and the only way I found out it turns on is if I let it sit for a whole day and then it turns on with no issue. I usually unhook the battery to reset the security system cause I believe its the security giving me issues but I can't find out how or why and I took it to a mechanic and it turned of for them just fine and drove like normal then I took it drove for 2 weeks and it does it again none stop every day I even went to get gas and it did it there and was stuck.
Please I need help understand this stupid car

 

[HotZ28]

When the engine fails to start, do you have a security light ON? Do you have another key to try? When you first turn the ignition switch to the ON position, does the security light flash for 3-sec & then go off?

 

[Mtilley_4]

When the engine fails to start, do you have a security light ON? Do you have another key to try? When you first turn the ignition switch to the ON position, does the security light flash for 3-sec & then go off?

I got a new key and security light doesn't flicker. It does light up when I try to turn the car on.

 

[HotZ28]

I got a new key and security light doesn't flicker. It does light up when I try to turn the car on.

That is normal.

 

[Mtilley_4]

Right so idk all I can think of is pcm or tune up

 

[HotZ28]

Tune up, nor the PCM has anything to do with a security issues!

 

[Mtilley_4]

Tune up, nor the PCM has anything to do with a security issues!

Thought the pcm was part of the security like the brain of the car

 

[Buick City Bert]

Personally I would begin with the starter relay in the under hood electrical center, try swapping it with a similar (maybe A/C) relay, but better still take your multi meter and check to see if there is 12V there for the high current (to the starter) and if there is 12V to the switch side (through the PCM and security module) when the key is turned to start. The relays usually have a little schematic right on their side showing the switch, and which contacts go where.

If there is no current to the key side of the relay I would look hard at the security "chip" on the key, that is actually a little resistor, when my 1997 had issue I measured the resistance, went to "Radio Shack" (gone now) and bought in line resistors that matched the value, cut the orange wires at the bottom of the steering column and soldered the resistors in there.
As long as the security module sees that resistance showing it believes the proper key is in place.
The contacts that make the connection at the key wear out with time and fail. This is a work around.

How to Determine Which VATS Resistor Value

Discover how to find your Vehicle Anti Theft System (VATS) resistance value without a key. Learn two methods for determining the correct resistor value for your car, ensuring the security and functionality of your GM vehicle.

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