RUSHTK

Hello all, My son and I are trying to get a 90 C4 to run and we have no key with chip, we just put in new cylinder, small town and the locksmith wants 25 dollars a key to figure it out, and finally the chevy dealer does not have a reader. Before we put any real money into it we need to see if it starts and moves, would greatly appreciate any direction you can give... well any good direction..grin.. Thank you!

RUSHTK

And I have been reading other threads but could not find one about a complete disable, Thanks.

RIC96

You're screwed.

https://www.corvetteforum.com/forums...ling-vats.html

RUSHTK

Well thanks for keeping it real!

aklim

Any way you can call another dealership with your VIN and have them make a key with the correct pellet?

frank j. moran

You need a VATs interrogator. Save yourself a lot of aggravation, bite the bullet and buy something like the attached, sell it after you are done.
https://www.clksupplies.com/products...e-double-sided

JimLentz

...or this.

aklim

I think it needs to have the key to do that

belairbrian

If the cylinder came with a standard (non-VATS) key. All you really need is a handful of resistors and some patience. probably way cheaper than $125.

frank j. moran

Correct, you need the key for that to work. You will need the interrogator to determine what key resistance the VATs module will respond to. The other option is to make up 15 corresponding sets of resistance values, drop the hush panel, disconnect the wires coming down from the lock cyl. and try each value (harness side) and try to crank the car. Time consuming.
The interrogator is a collection of the 15 key values, with a timer function built in 4 min.

mtwoolford

well of course you can; see the thread "Has anyone done a "vats bypass" on the cheap?", my post #5, dated 06-12-2017

mtwoolford

[B][/WARNING THE FOLLOWING WILL ALLOW CAR TO START WHILE IN GEARB]

make sure car is out of gear, in neutral if manual; park if auto

make sure parking brake is set

run jumper wire to small terminal on starter solenoid

place ignition switch in "ON" position

touch other end of jumper wire to positive terminal on battery

starter should engage, engine should turn over, and hopefully start

aklim

Exactly and he doesn't have it so his options are to blank it out in the ECM which is going to take a reflash and disconnect the system perhaps or to go one by one every 4 or 5 minutes. Which is why I don't think that will work since he has to buy all 15 or have his key.

aklim

OK. So you cranked the starter. IDK if the injectors will fire or not. If not, it won't run. Anyone know for sure if it is the cranking function that is disabled ONLY or whether the injectors will not pulse?

QCVette

A year or two ago my local Chevy dealer would make a new key with the correct resistance for about $25 from the VIN number. Just needed to provide proof of ownership for them to make the new key. That included the price of the new key and cutting it.

I would check with another Chevy dealer if yours can't do it.

Good luck.

I checked both an '87 and a '96 service manual and both show the fuel is disabled by the ECM when the VATS does not have the right key. So it is both the cranking and the fuel that are disabled.

TA

You need a $1.79 potentiometer and a multi-meter.

Remove the hush panel and find the orange wires that lead to the ignition. Follow the orange wires until you find the connector. Unfasten the connector and use the potentiometer to supply each of the 15 possible VATS resistances.

frank j. moran

Exactly, and that is basically what the interrogator does.

mtwoolford

well admittedly, I'm using a schematic for my 96 and the schematic, Engine Electrical , 6-211 only shows the Theft deterrent relay disabling (or energizing) the starter solenoid circuit:

the CCM "Theft Deterrent Relay Control" energizes the low amp side of the "Theft Deterrent Relay" and that circuit is completed through the clutch pedal safety switch or the auto transmission park/neutral switch;

once this relay closes, it allows the ignition switch, in the "start" position to energize the starter;

when I looked at "Engine Controls (Injectors) 6-279 I didn't see anything that could cause the injectors not to fire, assuming the ignition switch was in the "on" or "on/start" position

But hey, I could be wrong..been wrong before; still I think my idea is worth a try.

Cliff Harris

The ECM decides how much time to pulse the injectors to make the engine run correctly. In the case of a VATS failure, it pulses the injectors zero seconds each time. Not useful.

scrappy76

I wonder how often car thieves join car club websites to get any information possible to steal a car, especially a Corvette.
Just wondering.