Took my 96 out for a drive. When I got home I inadvertantly dropped my key on the ground in the hot sun. 30 min later I found it and went to start my car to move it into the garage. When I turned the key the dash lit up but no starter. After doing what is commonly referred to in my field as the definition of insanity, I kept trying to do the same thing over and over with the same result. Then, I started to think about it, and it seemed like this might be a security event where the key does not have the right resistance. So I went in the house and grabbed my spare, only to have the same result.

I checked resistance on both keys after coming into the house, searching here for 20 min (ie the key had time to cool down).. and they both read 7.4 ohms. Went out to the car, and it started.

So, Im wondering if the heat changed the resistance of my key enough to throw it off and turning it over and over put the vats into a temporary lockdown mode which is why my spare didnt work?

Anyone have a thought on this?

Im going to put my key in the sun right now for 30 min and see if I can reproduce.

Now Im worried about reliability which is why Id like to prove my theory. On the other hand, with a 26 yr old car with original plugs and wires I SHOULD be worried My biggest concern is, I have a dog seat with seat belt and like to take my boy out with me and Id be very upset if I got stranded on a 96f day.


I have a Tech 2 scanner (IE GM diagnostic), would I see this event? I may try it.. its the chinese knock off and reqiures a laptop so a pain to get running when Ive not done it in awhile.. but may do so.

EDIT: Heated up the key. Could not reproduce.

 

In the first event I would say that your correct in thinking that the chip in an overheated condition had a much higher value, so you're VATS system did its job and locked you out for 15 minutes.

Is it damaged? I don't think so and I would run it as you're normal key with the backup in you're pocket for a week or 2 but I think your or OK

 

I have serious doubts that heat would affect key pellet resistance. In my 89, I've had the rare no-start like you describe though. I figured it was because I've sprayed graphite in the ignition on RARE occasion over the years. (It smooths "tumbler" operation). Maybe you did that once/twice? One of these days I planned on wiring the correct resistor under the dash. I started plans to do this over 5 yrs ago. I don't think it'll strand you overnight. I admire your perserverence though!!!

I could even be that heat in the steering column caused enough expansion (in the ignition) to prevent pellet/VATS-circuit contact? FWIW, resistance goes up in wire as it ages. If you wanna guess [pellet] resistance rises with temp, include car wiring in that "equation".

EDIT: Maybe it's possible the key got damp/wet though?

 

Well, I couldnt repeat it. I just spent 3 hrs trying to get my damn vxdiag tech 2 clone to work.. Was almost there and then it crashed when connecting..I give! I may just buy the real thing. Its great when it works but then time goes by and things get upgraded.. I wish I had just used an old laptop and not ever touched it again.

Anyway... I dont know what is going on. I do have a check engine light on.. I pretty much know what it is.. its the secondary O2 sensor just being stupid again.. it just does that from time to time and probably needs to be changed out or maybe I am running rich.. who knows.

 

No.. I wouldnt spray anything non-conductive into the ignition tumbler.. I was thinking about using a little tube cleaner on the resistor pads.. if there is any corrosion on the connectors in there the tube cleaner would take care of that real quick and add a little bit of conductive lubricant.

I think what I should do is document the key bypass procedure.. not sure how that works.. I guess Id need a 8ohm resistor (in my case) which I should have on a shelf. Keep that in the console compartment.

Its interesting that it happened and then unhappened. Maybe I will try heating up the key one more time and check resistance myself rather than see if the car starts. Too late in the day now.. maybe tomorrow.

 

I was doing yard work for awhile and returned to find the same post on my screen. I edited it to include water/dampness as a possibility? Also, I agree with the post above. 8ohms isn't anywhere near the value of resistor each key pellet would measure. It will fall into one of the ranges shows in the table above.

 

This is a great site on VAT basics. Lots of good info.

https://www.lockmasters.com/site/pdf...%20Article.pdf

Learning how to understand what the VATS system is saying
Ledger Articles - 2007 By Steve Young

The VATS system can only communicate with you by way of a light on the dash or in some cases a text display on the dash. If you want to be successful, you need to learn how to interpret what the VATS system is trying to tell you. The light on the dash that the VATS system uses is usually called the “Security Light” because it usually says “SECURITY.” On some cars it may say “ANTI-THEFT” or just “THEFT.” If you know how to interpret the security light you can tell a lot about what the VATS system is doing and save yourself a lot of time and trouble. Below is a simple guide to reading the security light.
If the light does not come on – This means that the system is not working. The problem may be a bad connection, bad wiring or a bad module, but until you get the security light to come on you are wasting your time attempting to interrogate the vehicle.
If the light comes on and stays on as long as the ignition is turned on – This means that the VATS system is working and it read the resistor value you tried, but rejected the starting attempt because you did not use the correct value. When you see this response, you need to turn the switch off and wait at least three minutes before you try another value.
If the light comes on briefly and then turns off – This indicates normal operation with the correct key. The car should now start. If the car does not start, it is not because of the VATS system; begin looking of after-market alarms or other problems.
If the light blinks – This usually indicates that the vehicle has a factory alarm system and that the door is open. If closing the door causes the light to stop blinking, continue. On some vehicles however, a blinking light with the door closed means the same as when the light does not come on – see above.
If the light comes on and stays lit even after the ignition is turned off – This feature is not found on many cars, but when you do find it you are in luck. The security light on these vehicles acts as a timer for you. When the light goes off, it is time to try the next value.

 

The resistor on my key has a value today of 8,330 ohms. That’s not an acceptable value. I have a good meter but I borrowed my wife’s HF free meter and it measured the same. I ordered a six dollar set of resistors for the bypass. I hate removing the VAT system but a no start doesn’t work for me. Maybe order a new key and lock for later fix when it cools off in October. Very uncommon for a resistor value to change. Usually open circuit when it craps out because of excess heat.

 

So looks like I was reading my multimeter correctly and I am 7.4 ohms. Divide by 1000 to get ohms on your chart just so no one gets confused by this statement.

https://www.lockmasters.com/site/pdf...%20Article.pdf

 

I suspect you are looking at /1000 ohms on your meter. it still seems off based on the supplied chart however. Multimeters have always confused me but now I have an auto-ranging Fluke and it was worth every penny.

 

Thanks very much for this.. post this event I found out my battery was failing.. in fact it ended up failing so badly the sides bulged out. Replaced it and all is well again,. The low voltage per this doc likely caused my issue.