Why will my 2001 Saturn start and run fine unless it is cold out

Did they have a scan tool that was able to read body control module codes?Not all shops have the more advanced scanners that can read the body control module there expensive scanners.I already told you the pass lock sensor is integral to the ignition housing thats the housing that the ignition cylinder goes into.I have seen issues with those sensors before.I have also seen issues with the body control modules but not a whole lot of them.I have seen way more of the pass lock sensors fail.

The reason you cant find it at auto zone is because its part of the ignition housing and they dont sell that ignition housing.

1-800-694-3089 Thats the number for the saturns parts experts on the www. Parts. Com website. Give them a call and tell them your looking for ignition housing with the pass lock sensor in it. They will give you a part number and tell you how to find that part on there site.I have gotten hard to find saturn parts from them before its a good place to get factory parts. Iam not saying its for sure that the pass lock sensor is bad causing the no start when cold. But the security light should only be on when the security system has been set off. It sounds most likely a bad sensor though with the symptoms. But they usually set codes in the body control module thats why I asked are sure there scanner reads body control modules.

Did you only replace the ignition cylinder where the key goes in?If so that will not turn the security light on. Also a bad fuel pump wouldnt turn the security light on.

No that does have the pass lock sensor in it just a magnet that the pass lock sensor has to see to allow the car to start. So when it doesn start how long does it not start for?

So the security light on solid or flashing even when its warm outside?

Thats crazy I have replaced tons of those its the same cylinder and housing as the saturn vue so I have replaced tons of those cylinder between the two of them.I have had the security light come on after replacing a cylinder. Take a look on the bottom side of the housing where key cylinder slides into the housing. You will see a small connector thats where the pass lock sensor plugs in. Make sure the wires arent damaged or that connector isnt loose and not plugged in all the way. Actually unplug the sensor and replug it back in even if it looks like its plugged all the way. Let me know what you find and if the light shuts off.

If he tapped into the wrong wires did he do it right and buy a jumper harness so he wouldnt have to cut any wires?

Did you ever try what I asked you to try with unpluging and reseting the pass lock connector position and inspecting the wire?

So did he cut into any wires when he installed the radio?Or did he use a jumper harness that doesnt require cutting any wires?Also did you make sure the pass lock sensor is plugged in correctly and that wire going to it isnt damaged?