i have done the vats bypass, but the d@mn thing still acts up sometimes.
how do i remove it or totally disable it in my 92 RS w/ tbi?

TIA,
RS

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n(A.K.A FireBird88)
AOL SN: Zander0710
1992 Camaro RS 25th anniversary edition Adopted Feb,14 2000

Mods:
14x3 Open element w/ K&N filter, MSD GM blaster Coil and 8.5 SC wires, AFPR, 60psi. Fuel Pressure gauge, 3-Row Al rad. , 180* t-stat, Hooker 1 5/8 headers, 3" Catco cat, 3" Hooker Aero Chamber cat-back, "Ultimate TBI" mods

 

If you've followed the directions in the tech article, then the only choice is to get a custom chip with VATS disabled.

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1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

Actually it's really easy. There are two wires coming down your steering column and all you have to do is stick in a resistor from radio shack that matchs what you've measured your key to be. If you don't have the key then I would just try different resistors (a full pack from radio shack is only like $7 for too many).
If this doesn't work then you're doing something wrong or you are a one in a million case with a crap ECM or something.
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, Jon (91 RS too many mods to list)

[This message has been edited by JPrevost (edited October 15, 2000).]

 

I have a suggestion that I believe will be easier (and cheaper) than the tech article. I mentioned this several weeks ago in this forum. A search using the proper words should display it.

I have a ’91 Camaro, so I think your VATS is essentially the same as mine.

The “Pass Key Decoder Module” has eight wires going to it on one connector. I’ll list the terminal numbers that correspond to this connector, and what each wire does.

A3 = BLK/YEL to ground side of starter enable relay. Grounding this wire will allow this relay to operate when the ignition is in the “start” position, which will pass +12 to the starter solenoid.

B8 = ORN from the VATS 10 ampere fuse (+12 hot at all times). This is battery input.

A4 = GRY to the ground side of the “Security Indicator” instrument panel light. Grounding will illuminate this bulb when in “run bulb test” or “start”.

A1 = PNK/BLK from the ECM 10 ampere fuse. This is the "ignition" input, which starts the VATS timing sequence.

A2 = DK BLU to the ECM to enable “Fuel Cranking” (grounding will enable “cranking fuel” control in ECM).

B1 = BLK/WHT ground

A6 = WHT/BLK to the “A” terminal of ignition switch, to resistor (pellet) in key

B2 = PPL/WHT to the “B” terminal of ignition switch, to resistor (pellet) in key

Okay, to bypass the VATS completely, simply remove the connector from the module and connect ground (B1 BLK/WHT) to the starter enable relay (A3 BLK/YEL) and the “cranking fuel enable input” in the ECM (A2 DK BLU).

Doing this accomplishes what the VATS does electronically, except that this is permanent.

The tech article is nice, but it’s a lot easier to simply connect the ground to the two other wires. No fussing finding the proper resistor value. If you’re really cheap, all you’ll need are two paperclips to make the connections!

BTW, this will also keep the security indicator light off since you’ve disconnected module.

 

Stuart, have you already done this? Because is SHOULD NOT WORK. The "fuel enable input" is a pulse width modulated signal, and not a ground as you have described. If it did work, than the only explination is that the system failed AFTER a successful start, thereby putting the ECM into "Fail Enable". The ECM will remain in "fail enable" untill a correct start occurs, or battery power is removed, clearing the ECM. THE ECM MUST SEE THE FUEL ENABLE FROM THE VATS EXCEPT WHEN IN FAIL ENABLE. I would be curious to see if your car still starts after replacing your battery.

To further understand PassKey, check out this link: PassKey

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"I used to have a handle on life, but then I used it as a plunger and broke it" -The Wave

ASE Master Tech + L1
Savannah, GA
'87 Trans Am-K&N,Cold air induction, SSM SFC, Boxed LCAs, 8mm Accel wires, Flowmaster, 16" GTA rims.
'97 Bonneville SSE

[This message has been edited by GMTech (edited October 15, 2000).]

 

GM,

No, I was only reading the schematic from the Chevy manual. According to the schematic, the module only switches this wire to ground (on/off - nothing about pulsing it). These diagrams do not always detail the internal circuitry accurately, so that's what I get for not actually trying it!

What you stated sounds correct, so everything I said would be moot. You'd have to use the resistor trick.

 

Stuart, look at the diagram. You will see that the ECM sends a 5V reference through a "pull down resistor" and to the PassKey module. After the PassKey module sees the correct reistance, it will PULSE that 5V ref to ground. The ECM needs to see that 5v pulsed to a certain frequency before the ECM will turn on the injectors. So if the resistor trick does not work, and you are SURE that its still the VATS, then you will need a custom PROM so the ECM doesn't wait for the signal. You would also have to bypass the relay like you mentioned.

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

"I used to have a handle on life, but then I used it as a plunger and broke it" -The Wave

ASE Master Tech + L1
Savannah, GA
'87 Trans Am-K&N,Cold air induction, SSM SFC, Boxed LCAs, 8mm Accel wires, Flowmaster, 16" GTA rims.
'97 Bonneville SSE

 

GM,

Right you are. Thanks for the clarification!

 

Hey, while we're on the subject, I have a question for you guys.

When I finally get around to installing my alarm, besides the usual red flashing LED, I'd also like to have the dashboard "Security" light flashing.

If I'm reading Stuart's diagram right, I could simply supply a pulsing ground signal to the A4 gray wire, and the light would flash on and off. I would also insert a diode between the VATS module and the point where I splice on my alarm wire, so that ground won't get sent INTO the VATS module.

I know that the Security light probably uses a standard #194 bulb, and that if the car were parked for long periods of time, it would probably drain the battery. Other than that, though, does anyone have any comments on my idea?

 

Chris,

My comments:

Remember, +12 is removed from this bulb when the ignition is off, so you'll have to modify it so that this bulb has +12 all the time.

That shouldn't be too hard. Just isolate the bulb on the circuit board by cutting the run supplying +12 to it. Then, solder a small wire to the run connected to the positive side of the bulb and connect it to +12 continuous via a fuse, or a +12 continuous source that is protected by a fuse on your alarm.

I would confirm:

1. The grey wire does not go to ground with power removed from the VATS (more than likely, it does not).

2. Your alarm LED output can handle the current of an incandescent bulb. I doubt that it would. An LED typically draws about 20mA, but I measured 270mA (0.270 amperes) for a 194 bulb. I would use the alarm LED output to drive a transistor to switch the bulb on.

3. Your alarm LED output is switched ground or switched positive 12 volts. Depending on where the current limiting resistor is in this circuit, and what side is switched (positive or negative) to turn the LED on, you may only have 2-3 volts (20 mA) switched, or maybe the full +12 or ground, limited by the current capacity of the transistor/IC switching it on/off. Does the negative side of the LED go directly to ground? Does the positive side of the LED go directly to +12? Do both wires go to the alarm circuitry? Your best option will more than likely be to do as stated in point #2 above.

NOTE: You may not need the diode to isolate the bulb from the switched grounds of your alarm and the VATS to turn on this bulb. I don't have a detailed schematic of the VATS other than the basic diagram in the service manual. But since the VATS only grounds this wire to turn on the bulb, I would guess grounding this wire from any other source would not harm the VATS. But the diode would certainly not hurt anything.

If you do want to isolate it, put a diode (1N400X) cathode side toward the VATS module, anode side toward the bulb. Then connect the switched ground output of the alarm to the anode/bulb side of the diode.

Let me know how it turns out.