I am quite familiar with the effects of the VATS from reading posts on this board and from unfortunate personal experience. I understand that the VATS module reads the resistance of the key resistor and then sends a signal to the ECM. What has not been made clear to me is what exactly this signal consists of. I have read of someone fooling his 1990 Firebird by building a 50 Hz oscillator. His car was equipped with the Passkey II system. I do not know how this would work on the original Passkey system, or what would be changed on the original Corvette systems from 1986-1987. I am particularly interested in the latter, since I am trying to make a 'vette PROM work in my ECM. The installation is in a truck, so it is far from factory configuration, and the ignition switch and VATS module are long gone. Some schematics might be especially helpful. I'd feel pretty stupid if all it did in the early systems was ground the dedicated VATS terminal (B6, I believe). I already feel stupid enough for not realizing that the 'vette VATS was introduced earlier, and for dealing with the jackass I purchased the unit from. Any information or suggestions, other than "burn your own PROM", would be greatly appreciated. I have invested enough in just getting this thing to run right, and I need to draw the line before another $250 for PROM burning equipment.

 

Does that jackass still have the ignition keys to that vehicle? It would help out alot with measuring the resistance of the pellet in the key.

------------------
1989 IROC-Z 5.7L

 

If all you want is the VATS disabled on your eprom, why don't you just ask someone that is local to you if they would re-burn it for you?

If you can't find anyone local, just mail me your memcal and I will turn it off for you.

 

Yes, basicly you just need to find a frequency generator. PassKey II or PassKey I doesn't matter, they operate basicly the same way, just different pinouts. Also, different ECM's need to see different frequencies. I tried to use a VATS module out of a '94 bonneville, and it would let the starter crank, but it sent the wrong "fuel enable" signal, so the car just cranked.

I don't remember what the freq is, 50 sounds close. Next time I tear into my car, I will hook my meter up to the signal wire and look for future ref. Good luck.

------------------
If you live in Southeastern US, check us out!
South East Thirdgen


ASE Master Tech + L1
Savannah, GA

'87 Trans Am
S/D TPI retrofit including functional PassKey, 22# injectors,
JET AFPR, Ported Plenum,
TB Coolant Bypass, Custom Cold Air,
SSM SFC, KYB Shocks, Boxed LCAs, Wonder Bar,
8mm Accel wires,
Flowmaster Exhaust,
16" GTA rims,
Corvette Servo,
-->14.97 @ 94.9 MPH<--

'97 Bonneville SSE

 

Does anyone have a 1986 'vette schematic which would indicate where exactly the frequency is emitted? Unlike the F-body systems, as far as I can tell from wiring diagrams in Chilton's, the early 'vette VATS had a dedicated terminal on the ECM which is indicated to be unused on the F-body computer. They both use ECM 1227165.