Over the years of owning a 90, the one recurring issue I have had over the years is a vats no start issues. Turn the key forward, no crank and a solid security light. I've been stuck at home or out and about probably more often than successful to and from trips.
The ignition cylinder was original and had a bit of play with the key out of the cylinder so I replaced the cylinder and key. During this time I replaced the ignition switch, Fixed the tach since it was way off and replaced the worn out pivot pins to fix the play in the steering wheel.

It resolved the problem for a year or so and then started again. I figured maybe it was just a cheap AutoZone ignition cylinder. The keys ohm was still the same as when I purchased it.
I kept the old cylinder so I cut the orange vats wire and made a bypass using the same ohm resistance. I also put a rocker switch in line to complete the circuit and mounted it under the kick panel as a kill switch theft deterrent.
This worked for a the last two years and now the issue is back again. I thought this time the rocker switch might have gone bad so I disconnected it and completed the bypass circuit. Still a solid security light and no crank. I disconnect the battery and let it sit for and hour. reconnected the battery and still the same result. I disconnected the bypass and plugged the cylinder back in and then the car started.

Is it possible for ohm resisters to go bad within 2 years? I know that leaving the cylinder plugged in will cause intermittent issues again. From what I was reading it seems like the vats ohm resistance completes a circuit in the CCM that then sends a ground signal to the starter enable relay. The relay then allows power to the starter. Could the CCM be intermittently not be switching to ground?

Could it possibly be the neutral safety switch on the clutch pedal or the starter enable relay itself? I would think if it was either of those the security light wouldn't be on solid.

I'm leaning towards the CCM since I have also had the issue recently of the INF REST light coming on out of the blue. I checked the codes and 35 came back meaning something was wrong in the circuit. I tried to reset it a dozen times and it wouldn't reset. I bought the load tool for it off Ebay for cheap and figured why not see if its the DERM, squib or clock spring. followed the FSM procedures and the DERM and clock spring passed. Went through the reset procedure, plugged the squib back in and now the light is off again. FSM procedures state its a intermittent issue if it passed all the troubleshooting. The day those components no longer work Ill commit to a new steering wheel since new parts are unavailable and who knows how long or if used parts will last.

If it is the CCM, is it possible to just run a ground wire from the frame to a rocker switch then to the ground on the relay and bypass VATS all together while keeping a somewhat theft deterrent. ( don't get me wrong, if someone wants to steal something bad enough VATS wont stop them either.) Or just complete the circuit of the power to ignition and be done with bypass the starter enable relay all together?

I'm not really concerned if VATS stays or goes at this point. Original and numbers matching went out the window long ago. Id just like to be able to drive it without this headache anymore.

 

If the SECURITY light is solid on in RUN, the resistance is not correct. "Resistance" means the key, cylinder, wiring, connectors, or the bypass resistors. Ie, what the CCM is seeing when the key is turned to RUN.

EDIT: There was a lot more in this post, but no response from the OP, so it was not needed. Cheers.

 

iirc, even if you disconnect the battery and wait a while, the VATS timer will not reset. It needs to be the full length of time while connected to the battery.
Solid illumination is VATS resistance rejected.
I had all sorts of issues on an 89 and it turned out to be the wires in the column itself. I installed a simple resistor into the wires somewhere above the brake pedal and have never had an issue since.