Does the security light normally flash when trying to start the car? I never noticed how it acted before and now am having some starting issues.

 

The light will come on during bulb test. but in the run postiton it should not flash. it if does then you have a passkey fault in the system. you can have it scanned to see what code is set but a lot of times when there is a problem it's either the key or the lock cylender.. here is some info on the system that I posted on another forum...

Since 1986 GM has used the pass key system as an anti-theft device. It started in 86 with the vette and in 88 on the fbodys. Since then it is on many GM vehicles.

The system has 2 functions.
1 starter interupt and
2 it can disable the injectors elctronicly if the correct signal is not recived from the pass key system.

There are 4 components in the pas key system..

1 The key. it's a special key with a resister pellet on it. There are 15 different key blanks and 15 different pellet resisters.

2 The lock cylender... It is the same as a regular cylender exept for a pair of contacts for the reisiter pellet and a pair of leads witch connect to the vehicles wiring harrnes..

3 The pass key decoder module... a solid state module that checks for the correct resistence value so that the engine can be started.

4 the starter enable relay... it is betwwen the ignitio n switch and the starter relay. it allows power to the starter relay if it recives the signal from the decoder module...

if the vehicle has a NO crank condition then the pass key decoder module is not sending the "ok" signal to the ecm.. here is what you do...

If the light is flashing the passkey system has disabled the starter function. even if you suply power to the starter seliniod the car will still not start due to the injectors being disabled.

The most likely component to fail is the lock cylender ( mine broke 3 days after I got my car) First check the key and make sure that the pellet is not damaged or teh pellet missing..

If you have an ohm meter you can test the system. USe the ohm metter with the leads across the pellet and record the reading. I have the table with the correct resistences if you post them and can tell you if the key is bad..

Next,locate the 2 wire conector under te dash (should be white and orange wires) near the base of the steering colum and dissconect it.. incert the key and turn it to the start postion while measuing resistence between the 2 termonals going up the steering colum. This reading should MATCH the resistece of the key it self. and difference will set a no start condition. if there is a differnce. or in most cases No continutiy (like mine) you need a new lock cylender..

 

Generally[ and hopefully] cleaning the key pellet and the contacts in the ignition switch clear it up...
Good info above also..

 

it's possible if your key is old, for the resistor in the key to be worn down so that it is not sticking out of the black mounting insert far enough to make contact in the cylinder. if that's the case, you might try trimming the insert down with a file therefore exposing more of the resister.

 

Thanks for the responses guys.

I have a few more questions. It looks like my key is #7 ~1870 ohm. I would like to try to bypass VATS temporarily so I can drive my car to the shop. I talked to radio shack and they dont have anything close enough to 1870 ohm to work. Any suggestions?

Additionally what wattage should the resistor be for this?

And finally if I were to replace the lock cylinder (not the tumbler portion) does it include new wiring to connect to the cylinder and then the connector going to the VATS box?

Thanks again for your help.

 

First. you need to link several resisters to get the right value.



second. the lock cylender IS the Tumbler, it's basicly the part that you stick your key into the tuens the rack gaer and eventualy the ign switch.

Yes the new tumbler comes with the 2 wires on it. you have to feed it down to through the steering collum and then it connects at teh bottom of the collum right nest to teh AIr bag connector


you can test the cylender like I posted before ..




Next,locate the 2 wire conector under te dash (should be white and orange wires) near the base of the steering colum and dissconect it.. incert the key and turn it to the start postion while measuing resistence between the 2 termonals going up the steering colum. This reading should MATCH the resistece of the key it self. and difference will set a no start condition. if there is a differnce. or in most cases No continutiy (like mine) you need a new lock cylender..

 

Thanks.

I'll give it a try this evening. Just couldnt remember if resistors needed to be wired in series or parallel. Got that all staright now. Will post results later.

 

A 'search' in LT1 tech for VATS will turn up a lot of info for you also..
How to bypass it etc...
I remember just last week posting in one..

 

Just wanted to say thanks to everyone for your help. I hooked the resistors into the VATS cable tonight and the car runs great again.