'03 Security Issue???
Thread Starter
Racer
Joined: Aug 2006
Posts: 403
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From: Huntsville Alabama
'03 Security Issue???
I purchased an OEM fob. I "taught" the new fob via instructions on the forum. The fob will lock and open the doors and the hatch. What I noticed is when I use the fob to unlock the doors, the car will not start. I get out of the car and lock the doors and then I open the door using the key. From this the car will start. What am I missing?
Tech Contributor
Joined: Dec 2003
Posts: 19,384
Likes: 87
From: Horncastle Lincolnshire, England
2023 C5 of the Year Finalist - Unmodified
Its a strange one
The fob shouldn't have any input to the start sequence. The fob sends an RF signal to the receiver and then to the computer which energizes a relay and unlocks the door.
The VATS controls the security funtion on the car. When you put the key in the ignition, the pellet registers a resistance with the computer and the BCM turns on the fuel if it gets the correct reading. If it doesn't get the right reading the security light stays on and it wont start.
When you unlock with the fob and turn the ignition on do you still have a security light on the panel? Presumably if it starts by opening with the key the security light is out?
I'd guess the problem is with that particular key not the fob.
Firstly if your other key works fine, clean the pellet on the bad one. It could be that using the key in the lock cleans it up enough to send a reading.
Try wiggling the key in the ignition if you have a security light and see if it will go out. If so it could be a worn ignition barrell but I'd bet on a dirty/bad VATS pellet.
The fob shouldn't have any input to the start sequence. The fob sends an RF signal to the receiver and then to the computer which energizes a relay and unlocks the door.
The VATS controls the security funtion on the car. When you put the key in the ignition, the pellet registers a resistance with the computer and the BCM turns on the fuel if it gets the correct reading. If it doesn't get the right reading the security light stays on and it wont start.
When you unlock with the fob and turn the ignition on do you still have a security light on the panel? Presumably if it starts by opening with the key the security light is out?
I'd guess the problem is with that particular key not the fob.
Firstly if your other key works fine, clean the pellet on the bad one. It could be that using the key in the lock cleans it up enough to send a reading.
Try wiggling the key in the ignition if you have a security light and see if it will go out. If so it could be a worn ignition barrell but I'd bet on a dirty/bad VATS pellet.
