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Security light - car wont start - what to replace?

krnlpnc

Member
Joined
Feb 14, 2005
Messages
22
Location
California
Corvette
1998 Artic White Coupe
Like many others I too have a the dreaded "security light" no-start issue. I know the problem is caused by the chip in the key not being picked up by the lock cylinder, but I'm wondering how much and exactly what parts are needed to correct the issue. Of all the posts about it, no one seems to say what they did to actually fix it. The two relevant codes I'm getting are:

B2721 PASS-Key Detection Circuit
P1631 Theft Deterrent System Password Incorrect

It's been happening randomly for over a year but started happening daily in the past week as the weather got dramatically warmer. It's a '98 and I only have one key. I'd be grateful if anyone has successfully resolved this and knows the fastest way to approach the repair.

GM and their shoddy electronics strike again - this is incredibly frustrating!! :bash
 

tstar

Well-known member
Joined
Jul 5, 2006
Messages
52
Location
Central PA
Corvette
1999 Pewter Coupe
First thing to try is cleaning your pellet with rubbing alchol. FWIW I'd get a spare key made regardless and give it a try as well...
 

gmjunkie

Well-known member
Joined
Nov 11, 2004
Messages
4,547
Location
Old Fort NC/Vero Beach FL
Corvette
03 Z-51,78 L82 Coupe
First thing to try is cleaning your pellet with rubbing alchol. FWIW I'd get a spare key made regardless and give it a try as well...
Also get some of this and clean contacts in ignition switch!!.........:upthumbs
attachment.php
 

FLIR_man

Well-known member
Joined
Sep 12, 2002
Messages
89
Location
Winter Park, Fl USA
Corvette
2000 coupe Metallic Blue
I had a Firebird with the same problem and I measured the resistance value of the key and cut the wiring near the electronics and soldered a resistor. A year later I had the steering column apart for a different reason and found the wire had broken.
 

krnlpnc

Member
Joined
Feb 14, 2005
Messages
22
Location
California
Corvette
1998 Artic White Coupe
Since it's hard to know if it's the resistor pellet in the key, or the ignition cylinder it was suggested I have the resistance in the key measured as a first step. The guy at the parts counter of my local dealer looked at me like I was an alien for asking him to check, he did and said "the key looks okay, it's an 11". At least I now know which resistance value my key is, I'm thinking the next step is to replace the ignition cylinder. Still looking for more info on doing that. Any here ever replace one?

It's an older article, but good info on the VATS key system which I imagine is largely unchanged since the late 80's: http://corvette-nation.com/corvette-forums/viewtopic.php?t=29
 

FLIR_man

Well-known member
Joined
Sep 12, 2002
Messages
89
Location
Winter Park, Fl USA
Corvette
2000 coupe Metallic Blue
Before I replaced the ignition cylinder I would verify it is bad. You could insert the key and measure the resistance at the connector that connects to the VATS module. Verify that the value does not change by more than a few ohms when inserting after removal. Cheep ohm meters are available at Radio Shack.

The "11" defines what the resistance range is as noted in your link. Unfortunately I do not know if the table has changed for C5s. You could go to Radio shack and have someone there measure the key and then buy the resistor from them. Then follow the directions for installing ahead of the VATS module.
 

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