1990 Corvette VATS Variation
November 6, 2011 No CommentsI recently attempted to make an ignition key for a 1990 Corvette, using standard VATS/PASS procedures. I got a very rude awakening. With the doors closed and fully charged 12 volt battery, I completed one full cycle of all 15 resistance values without the vehicle starting. I put a fresh 9 volt battery in my interrogator and tired again, with the same results!
I produced a second interrogator, checked the 9 volt battery and tired two more sets of 15 with no luck. With the aid of dealer Technical assistance, I reached a GM engineer and explained my problem. After a lengthy conversation with him, he was convinced was faulty or I had overlooked something.
With nowhere else to turn. I called the only plant in the country where Corvettes are built … Bowling Green Kentucky. I was lucky enough to reach an engineer named Gordon Killabrew who knew exactly what to do. The correct procedure for generating an ignition key for the 1990( and only the 1990 model), is as follows:
Make your first three attempts using your selected R values the normal four minute time delay between attempts. Following the fourth attempt, go to a 10 minute delay between attempts. If you don’t use a 10 minute delay, the ten minute delay will start to recount just like the three minute delay does. This sequence was caused by change in the central control module CCM on the 1990 models only. 1991 and up Corvettes went back to the normal three minute delay sequence.
I do a lot of Vats/pass work and have only encountered this problem on the ’90 Vettes. The engineer in Bowling green told me that just he and a few others knew of this problem. Since the change was rectified so rapidly, this information will not be found in any shop manual or service bulletin that I’m aware of.
By the way, the car started on #7 after using the ten minute delay procedure.
