1990 theft deterrent system problems
 

I have owned a 1990 convertible for the last eight years. This car has never been my daily driver, and was stored for the last couple of years. Anyway when I unlock it if the security light on the gauge cluster is not blinking then the car will not start. In fact it will not even turn over. I used a Autoxray scanner and it came up- theft code. Also when it does start it will run fine however sometimes the LCD will go blank, at this point if I shut it off its always dead. I have taken the car apart and tried many things with no luck. My CCM seams fine and the theft system along with everything else runs through it. Any IDEAS ????????

How is the Battery? Measure the voltage at the battery and alternator with engine running.

The battery is a fairly new Die-Hard Gold, but I did have to charge it. I did not check it when the car was running, but it showed 12.8 or so on a meter and seamed to have plenting of cranking amps. Also I disconected while working on it, and / or charged as well. Should I look into this more?

I will go try this now providing it will start.

checked battery
 

14.23 at battery, and 14.30 at altenator while running. Shut off and security light was blinking then dropped hood with door slightly ajar and interior lights went off as did security light. Locked car, waited few minutes then opened with key and security light was blinking again.

Do a search on "VATS" and you should find your answer. I found this thread after a quick search. http://forums.corvetteforum.com/c4-g...e-on-90-a.html

VATS System?
 

Is that the chip on the key? I think Eklers sells a by-pass that may be worth a try, howerver I think the problem is before that. As I said if I open the door and the security light is not blinking (before even putting the key in the ignition) the car won't even turn over. I think it may have something to do with the computer control module ?????

Did you read the link I provided?

The VATs (Vehicle anti theft system), is controlled by the ecm and the resistor in the key is just part of the system. This was also, in the link I provided, look to the left side of the page under 1990 repair instructions. http://www.vatssucks.com/

Vats
 

This makes sense and the links are good. Is there a differance between the VATS system and the theft deterrent system or are they the same? The reason I ask is because I have a 1990 section 8 A electrical diagnosis service manual supplement and it refers to a UTD (Universal Theft Deterrent) and the VATS. Thats why I assumed my VATS was working properly.

There are several individual components that make up the VATs system.

The UTD is probably the generic term used to describe the VATs system as a whole in the manual (I'm just guessing).

I will order and try the VATS by-pass, at this point I will try anything because I just want to drive my car. Thank you and if you think of anything else please let me know. There is a Corvette specialty shop in San Diego that I may try as well.

Check out this site: http://www.vatssucks.com/

Mike O,

I don't think you have any problem with your VATS system.

The VATS system is all about the key resistor being read by the Ignition switch, and passing that resistance to the CCM, so that it can decide if it should enable the starter circuit when you turn the key.

However, the door key lock does NOT use the VATS (notice the key doesn't insert far enough to touch the resistor contacts).

Can I presume you are unlocking the car with the key in the door lock?

If so, there's a chance the switch behind the door lock is either not centering up properly or has corrosion and is making good contact sometimes and not othertimes.

There's also a chance that one of your door switches is not operating correctly (believe your 1990 had two, one by hinge, one by latch). This could also have something to do with the 'security' light not blinking -- the door switch might not be sending the correct signal to advise the door has been openned.

Very good point about the VATS working because my problem seems to be before I even get my key in the ignition. Also, my car has two keys, one (round) for the doors and the (square - chipped) for the ignition. I had the same idea about the door locks and took off my passenger side panel because being a covertible, if the alarm is tripped that is the side to un- lock to reset the system, or so I've been told, and it did work. Anyway everything was fine and seemed to work. I only recall one door - open switch near the outside of the door, not the hinge? I will definitely look into this more. What do you think about the LCD and dash lights going off after the car warms up? It seems my interior lights go out then as well.

security light
 

hello mike o... im wondering if you have made any more progress with this issue, my 90 vette is having the EXACT same symptoms.. the LCD in dash will randomly freak out and often go blank, and the car will only let me start it when the security light is flashing. I have tried numerous different ways to trigger the security so i can start it but nothing will consistantly work... it just comes on at random?

the other day after sitting in the verizon parking lot for 2 freakin hours waiting for it to let me start it, :toetap: i opened the door to get out and about 10 seconds after i opened the door i heard a relay (or 2) under the dash click and then the dome light came on and the security light started flashing again and it started... my point being is im kinda leaning toward either a bad ground somewhere?? possibly in or around the insterment cluster since most of the weird and random stuff seems to be in that area?? OR.... im thinkin maybe a bad or weak relay somewhere under the dash.. i've heard it click on a few times since then, and when it does click, everything seems to work but not for long? it sounds like it is comming from under the passenger side of the dash area or maybe behind the driver info center??

anyway, sorry about the long post but i figgured it may help you (and me) if i threw my 2 cents out there.. atleast now i know im not the only one out there with this issue.. :lol: . please post any progress/ideas you may have and i will do the same if i track anything down...I JUST WANNA DRIVE MY CAR :D THANKS!!!!

Sorry for not responding sooner, I have twin 13 month old boys and of course the full time job. I have kinda givin up for now because my car is in the garage, and not my daily driver. I have gone so far as taking out my CCM from under the dash, and found nothing visibly wrong with it. I have removed my gauge cluster with the same results. My very talented friend and I have spent countless hours taking the car apart , reading my 1990 SECTION 8A ELECTRICAL DIAGNOSIS SERVICE MANUAL, trying EVERYTHING, and putting the car back together. My next step my be towing it to a Corvette Specialty Shop in San Diego. I REALLY WANT TO DRIVE MY CAR AS WELL, so I know how you feel. I PRAY that soon someone can help us, because a tow, and shop time, is big $$$$ I don't have right now. Sorry I don't have anything more to offer you other than - Hang in there, stay in touch, and don't stop lovin your VETTE.....

Hey Derek is your VETTE a Coupe, or Convertible?

coupe...
 

mine is a coupe... and luckily its not my daily driver either... i actually just got it.. belive it or not i traded my supercharged 89 ford mustang straight accross for it :thumbs: sucker...:rofl: i hated that car, i'd much rather work on a vette than any ford :)
anyway.. i have a freind that is an electirc guru so maybe ill see if he can help look it over when i tear into mine, if i see anything i'll let you know ASAP... its gotta be the same problem with both cars?? in the mean time i guess we can hope someone has some ideas for us..
thanks for gettin back.

Been there . . . . If only it was that easy. As far as the state of Wisconsin is concerned, next year my '90 will be a certifiable antique and can be licensed as such. As you're most likely discovering each and every day, driving an antique takes work, serious work, not to mention time and money. No way around it.

If you don’t already have one, buy a Factory Service Manual. Read it. It will become the best tool in your box. The second best tool is to learn how to search – really search – this forum. The answer you’re looking for is tucked away in the archives someplace. Guaranteed.

Check this: Avoiding the Tow Truck. Read between the lines; it may help.

THANK YOU SO MUCH for the link Avoiding the Tow Truck, that is very, very good information! I have the section 8A electrical service manual for 1990, and a very talented friend to help me with this as soon as we can get the time to look into it again. I'm new to the Forum and not very computer savy as I pound nails for a living, however I will do my best to search the Forum and the rest of the the internet before I take my car apart again. DEREK - Look into the link above Avoiding the Tow Truck . I only looked at it briefly but it seemed like like what my friend was looking for when we had my car apart. I'm not sure how this whole Forum works but I hope you get or read this soon. Also I hope your electrical guru is better than mine and we can solve this, summer is coming,(even though I live in San Diego) & I WANT TO DRIVE MY VETTE !!!!! THANKS