B2721 PASS-Key Detection Circuit
Thread Starter
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Joined: May 2004
Posts: 59
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From: Coatesville PA
B2721 PASS-Key Detection Circuit
I'm getting a Code B2721 and my SECURITY light on the dash is coming on at random times.
I have no problem starting the car.
Any suggestions on where to look for the cause of the problem?
I have no problem starting the car.
Any suggestions on where to look for the cause of the problem?
Intermediate
Joined: Oct 2004
Posts: 44
Likes: 0
From: Charlotte NC
B2721 code
Dude, go to the passenger footwell and pull fuse # 23 for 10 seconds. It sounds like your CBM relay is out of sinc with your BCM. It happens in my car occasionally. I clear the DTC codes after I do it, but you don't have to.
Racer
Joined: May 2006
Posts: 352
Likes: 42
You might have the same problem I recently had, the contacts inside the lock cylinder that read the PASS resistor in your key may be going bad. I was able to bypass it by putting a REAL resistor in the circuit so I could start the car. If cleaning the contacts on your key don't help, PM me and I'll post how to put a resistor in. It's a pain but works....
Doc
Doc
1st Gear
Joined: Oct 2005
Posts: 1
Likes: 0
You might have the same problem I recently had, the contacts inside the lock cylinder that read the PASS resistor in your key may be going bad. I was able to bypass it by putting a REAL resistor in the circuit so I could start the car. If cleaning the contacts on your key don't help, PM me and I'll post how to put a resistor in. It's a pain but works....
Doc
Doc
I'm having a problem starting my '98. Key in one way and the security light stays on...flip it over & it goes off in the Start mode, but won't start, and then the Security light comes on again. Would by-passing with a resistor get it started if the PASS key is bad?
Thanks !
Stan Evans
Drifting
Joined: May 2004
Posts: 1,917
Likes: 18
From: Tulsa OK
Doc,
I'm having a problem starting my '98. Key in one way and the security light stays on...flip it over & it goes off in the Start mode, but won't start, and then the Security light comes on again. Would by-passing with a resistor get it started if the PASS key is bad?
Thanks !
Stan Evans
I'm having a problem starting my '98. Key in one way and the security light stays on...flip it over & it goes off in the Start mode, but won't start, and then the Security light comes on again. Would by-passing with a resistor get it started if the PASS key is bad?
Thanks !
Stan Evans
Stan,
I too have been through this. You can either replace the lock cylinder or wire in a resistor, but the resistor method basically tricks the BCM into thinking the correct key pellet is being used (and therefore your anti-theft feature would be useless).
