What is the little red system armed LED in the drivers door doing? Is it continuing to flash all the time which indicates that the alarm is still armed? Have you tried unlocking the car from the passenger side to see if that will disarm the security system? If the car alarm has triggered it would be normal that the car will not start because the security system will be holding the starter cut relay in the open position.
With an aftermarket security system you are kind of on your own. The fact that your car has an aftermarket security system makes it impossible to be definitive about what the problem might be. I also know nothing about the operation of the compustar system. Does it require that you always lock and un-lock the car using the remote (that would seem like a really bad design) or does it normally allow you to lock and unlock the car with the key (which should dis arm the system).
My knee-jerk reaction in cases like this is get rid of the aftermarket security system. The car already has a security system and you don't need two. Anecdotal evidence on this forum points a finger at aftermarket security systems as being the cause of a lot of false alarms and starting / dead car problems. However, in your case that recommendation is tempered by the fact that you have a 1992 (thank-you for including that important detail). The 1991 and 1992 NSXs were the subject of a Technical Service Bulletin issued in 1993 (TSB 93-007) which dealt with problems with the switches in the door latches leading to problems with the security system. This TSB used to be in the Prime Library; but, is no longer there after the web site up-date.
@drew might have a copy. The TSB describes testing the latch switches (same tests as described in the service manual) and if it fails the tests the whole latch mechanism has to be replaced. Replacing the latches is expensive and non trivial. It is probably going to be $1500 or more per door if you don't do it yourself.
So, the latch might be the problem because the switch in the latch has failed. This may result in the security system not getting the message that the door has been unlocked which should cause it to disarm. When you open the door this then triggers the alarm. Or it might be that the Compustar system is in failure mode or perhaps the original NSX security system has failed.
So, pick your poison as to where you want to start.
- The easiest thing to do is just unplug the Compustar module and see what happens. Depending on how the Compustar is integrated with the existing NSX security system this might resolve the problem and return the car to its normal operation (if the Compustar is the problem). If that appears to resolve the problem you can then decide what you want to do with the Compustar system. Personally I would remove it and delete the harness interface restoring all the vehicle wiring to original condition.
- Since you have a 1992 and if you have no maintenance record of the car going through the TSB 93-007 service I might be inclined to check the operation of the driver side door latch switches. If the alarm disarms when you use the passenger side key that might point a finger at the driver side latch switch. This requires that you remove the inner door liner to access the plugs to the door latch so that you can test the operation of all the switches in the latch mechanism. Removing the door liner is a non trivial exercise; but, doable if you have reasonable mechanical skills. If the latch switches test out OK then that points a finger at the Compustar system or the OEM security system.
I don't know whether there is any way to do a diagnostic check on the Compustar system if it looks like it has failed. That is something that you would have to check out. If
