Ben Miller

I have lost my keys to My 87 corvette can I pull the resistance reading from the wires under the kick panel with a ohm meter? And I don't want to bypass the module.

Cliff Harris

The circuit that compares the key resistor pellet is inside the VATS module. You cannot measure it externally.

There is more information here:

https://www.corvetteforum.com/forums...schematic.html

Ben Miller

it seems you could seen the interrogator is just a ohm meter with 15 different resistance values.

WVZR-1

Having no spare key I doubt that you have the "mechanical cut-code" of the key either so the most reasonable approach would be to use a GM VATS INTERROGATOR along with a new cylinder and key for replacement. The GM Interrogator allows a simple rotation to various values. Others are more difficult to manage.

If by chance you had recorded the "mechanical cut-code" it becomes much less aggravating. Do you have that code?

Where are you located? I have a GM Interrogator

I've seen it debated before in what year the code was removed from the actual cylinder in the column but attempting to retrieve it from the cylinder in the car would generally result in a failed electrical connection and require a cylinder purchase anyway.

Experienced persons wouldn't have an issue.

Ben Miller

in Michigan at the moment but live in Tennessee I came to pick my vette up seen I moved

hcbph

Here's an offbeat approach, but it should work but will take some time and a little money. This is assuming you don't have someone with the right equipment to read the value out of the car (interrogator?).

First a locksmith can cut a key based on your ignition or have it replaced. You will be needing a key that can turn the ignition cylinder at a minimum.

Now the fun part. First you're going to need to get the list of the 15 different keys and their respective resistance values (I've seen it on the web before but don't have the url, you'll have to look for it). You'll need a handful of resistors with various values. Near the bottom of the steering column is a 2 wire lead (1 is orange IIRC) that has a connector going to behind the DIC. There's a connector in the middle about 12"-18" from the column. Wire up a combination of resistors to match the range of the first value for keys and plug that into the connector side going behind the DIC. With your new key, see it the car will turn over or not. If it fails, there's a reset time (5-10 minutes I think) so while waiting for that, make up a resistor set for the 2d value and try again after the wait period. Keep doing that till you get to one that works - that's the value of your resistor requirement for the key. Now get at least 2 keys (or more) cut that have that resistor value on the key. Hook the connector back up and you should be 'good to go'.

It would be a pain to do it this way, just depends on the options you have.

Obviously it would have been better to have a valid spare key in the first place but you can do it if you want to.

Good luck.

PS - I read somewhere the resistor value is read into the ECM on the first startup so unless you replace that, you have to figure out what value the car has saved in it's system.

zr1fred

Call GM, there's a slight chance they might have the key codes. Then call a few locksmiths. They should be able to make you a set for $200-$300. Unless you are home with your tools or know what you are doing, there's a good chance you might break something. Yeah, it sucks, but sometimes its cheaper to bite the bullet.

Ben Miller

ok I've got the vats module open and I see the resistor can I measure it on each side of the resitor and get it that way?

Ben Miller

I've got the old lock and tumbler plugged into the vats and have a key from a 89 and plugged that into the old one and used my copy key to try and start it .and it sound like the fuel pump kicks on. And by the way 89 vats module is different from a 87

Ben Miller

JimLentz

I think it is the resistor next to the "W" connector/pin.

Cliff Harris

It's the resistor next to the fuse (yellow cylinder) at the bottom left of the picture. It's below the bottom of the picture.

WVZR-1

Use "resistor color stripes" to establish values. In Cliff's snapshots it appears to be a 5-stripe resistor. It should be relatively easy using that information for confirmations.

It's likely not on an '87 cylinder but since you'll need to likely go there anyway carefully remove the cylinder and see if there might be a mechanical code stamped on the case. It's unlikely but possible.