My car is a 1991 L98. Last night, I inserted the wrong key and it turned to the start/run position, but of course did not start. Today, It won't start with the correct key and displays an ECM code 46. I can't find any referance to this problem or how to remedy it in the service manual. Is there some reset or something on the security system?

 

ECM code 46 is only present in real time. It isn't stored as a history code so your CCM is looking at the resistance value it's receiving from the key cylinder and isn't happy with what it's seeing -- meaning it doesn't match the corresponding value stored in the CCM -- and it's sending a command to the ECM that results in ECM code 46.

What I would do is measure the value of the pellet in the key, take the driver's side lower trim panel off and find the VATS connector where it comes out of the steering column. It will be a two pin connector and will not be colored yellow (that's the S.I.R. airbag connector).

Temporarily short the two pins on the connector half that is traveling away from the steering column with a resistor having the same (within 1%) resistance as what you measured on the key. Put the key in the cylinder and try again to start your car.

If it starts, most likely the lock cylinder was damaged when you used the wrong key and will either have to be replaced or you will have to permanently use the resistor to fool the VATS. The CCM is probably seeing either a short or an open now on the lock cylinder and that is why it is causing the ECM to show code 46.

If you are curious, you could also check the CCM and see if you are getting a code 51, 52 or 53. 51 is invalid key (wrong resistance), 52 is showing that the lock cylinder contacts are shorted either to one another or to ground and 53 means there is a open or there is a short to battery voltage somehow.

Hope this helps.