My daughter'* '97 Lumina is running great after some maintenance and
repairs, but now it is having issues with the anti-theft system. The key (with
its hidden resistor) is not making contact very consistently with the ignition
lock/switch. I want to bypass this key resistance system. I have tested the
resistance of the key'* contacts and have attached a photo of my findings.
Anyone ever performed this? Do you know which resistor(*) I'll need to
solder into the security circuit? Thanks in advance for any assistance!

What is the reading if you put the switch on 200?

We have quite a few posts here dealing with this issue.

Just do a search for "vats bypass"

Its simply installing a resistor equal to what you see on your DVM and cutting the 2 wires that go to the ignition switch and soldering the resistor to the wires.

This makes logical sense. I'll put it on 200 and check and let you know.

BTW, have you heard anyone have the experience that "the body control module will not work if that resistor is left installed all the time"? Someone informed me that this was the case. It doesn't make sense to me that the ECM would know or care if the key was in all the time or not.

Looks like my key is lucky #13.
VATS Code: Resistance Value In Ohms:
1 402
2 523
3 681
4 887
5 1130
6 1470
7 1870
8 2370
9 3010
10 3740
11 4750
12 6040
13 7500
14 9530
15 11800

I have never heard of the BCM having an issue with the key in all the time.

Yeah, I don't think it checks until the key is turned on.

My logic led me to the same conclusion that the electronics shouldn't care if the circuit was complete all the time or not. I simply was informed by another person who seemingly has lots of knowledge about GMs, especially late 90s cars like the the Lumina, stated that the BCM is reading the connection even when the switch is off in mili-amps and that will cause issues over time. Other than that, I get no real details from him. That'* why the ask outside of what makes sense to my understanding of electronics (which is admittedly quite minor).

Just to be sure, this error can stop a car while it is idling yes? She just had her Lumina'* engine stop at a traffic light and it wouldn't restart (no starter and probably no injectors, I'll check) and she had to have it pushed off the road. Is there a way to check and insure this is the issue? I have checked and had checked the battery, starter, alternator and they're good. Plus the myriad of things we just did to the car a few months ago (literally everything). I trust this PassKey nonsense is it. What an absolutely stupid design to live with for my daughter and me.

The antitheft is only there to prevent engine starting if working correctly. Once the engine is started, it will not shut it down. This is a safety issue.

Again, we've had many people here do the VATS bypass and I have yet to hear of one causing issues.

Thanks, that'* my thought as well. Logical.

Quick question: while I'm awaiting some resistors to come in the mail, I went out to check again what was happening. The car wouldn't start.
With the switch in the on position, this occurs:
1) The dinging happens at normal pace and sound (door open)
2) No lights on the dash illuminated
3) When the switch is pushed to start, there is a slight clicking sound (reminds me of back in the day when a starter relay didn't have enough power from the battery to turn over. But the battery and alternator check out as good and within spec
4) As an aside, when I tried this a few days ago at my daughter'* after checking (pulling out and bench testing) the alternator and battery, I used my son in laws key and it started right up. I have the son in law'* key now and this....


Still wondering about this PassKey system causing all this as well as the stall (if they are related).