Thanks for confirming what I thought. Appears that there are two Hall effect sensors in the lock cylinder itself - being the sensors for the Passlock system. I've "recalibrated" the system to the original key, and I even drove the car and did several key-on, key-off cycles.

AFAIK, the starting problem only occurs after the Security light comes on while driving (by that I mean the light comes on, and then next cycle is a no-start).

Right now it seems like I can either spend $160 for a new ignition cylinder, or I can pay $180 for the Passlock override. The particular system I'm looking at disables all versions of Passlock (assuming it generates the 50 Hz signal straight to the BCM) without actually rigging it with the resistor. This style doesn't bypass it only during startup, as is available for remote starters.

I've seen numerous other "remedies" but all the others seem to be hit or miss. So either I replace the lock cylinder or buy this unit.

How to FULLY Disable Security in GM Cars and remove GM VATS PassKey and Passlock systems
Yeah, I know the page is riddled with grammatical errors. Otherwise, it seems legit.

GM VATS Bypass Module For LS1 and LT1 GM VATS Bypass Module For LS1 and LT1 [gmvats] - $24.95 : 3rdBrakeFlasher, E-commerce web site

thats just the fuel enable, alot if not all the obd1 era vats have a start enable relay that has to be bypassed as well

The one you show says it applies to LS1 and LT1 engines, and for cars with the resistor chip in the key. Do you know if it applies to Passlock as well? (No chip in key) Also, the Intrigue has the... L36 engine? Not the two V8s listed. I don't mind paying LESS for an item, I just want to be absolutely sure it'* compatible and will do what I want it to do. After all, I only make $11k a year. LOL

sorry didnt read fully, i thought you were talking about the car in your sig. if you have that type it would be easier i think to have your pcm "tuned" to not care about the security. might be the same money as that new rockies thing but you get rid of any possible faults with the wireing and possible not working with your car

Update: It'* been a while, thought I would give you all an update on the Intrigue.

After about a week of my mom driving the car, the HVAC system did indeed gradually reset itself, and is functioning normally.

After re-calibrating the idiotic ignition sensor to the original key, the Security light has not come on - ever - and my mother has been using the new copy of my master key ever since.

Everything is okey-dokey, back to the good old reliable car that she always has been. And edging ever closer to the 200k milestone. Although it'* finally time to replace those original rear rotors, they sure tore up the new pads I put on 15k ago.