Random Tech Questions

[AggieTJ2007]

besides the relays quitting I have had the motor on mine smoking twice and it still pulls great, maybe not as strong as others but plenty strong for the jeep.

[Hot Pocket]

Does anyone have any experience bypassing a passlock security system? GM sucks.

[AggieTJ2007]

Does anyone have any experience bypassing a passlock security system? GM sucks.

You mean VATS you need a programmer or techII to do that

[Hot Pocket]

You mean VATS you need a programmer or techII to do that

yes, VATS/Passlock same thing. The programmers cost a ton... is there another solution? I have read that it's possible to reproduce the output signal on the theft deterrent module while bypassing the module altogether, but how would you do it if you had a programmer or tech II?

[AggieTJ2007]

yes, VATS/Passlock same thing. The programmers cost a ton... is there another solution? I have read that it's possible to reproduce the output signal on the theft deterrent module while bypassing the module altogether, but how would you do it if you had a programmer or tech II?

A quick Google search yields that it is easily done with some resistors and a relay or two

With a programmer you just go into the computer and disable it

[Hot Pocket]

What you're talking about involves fooling the VATS module into thinking that the proper input resistance is present. That is fine, except that it is the module itself which is faulty. I know there is a way to bypass the module and make it work.

edit: which programmer has the option to disable the VATS? From what I have read online, there is no option in the tech II to flat out disable it.

[mudtoy67]

Here's info on disabling vats. This page is primarily about building the resistor to bypass vats. If you scroll to the bottom of the page he includes links to a build page for a signal generator to replace the module and a link to a place that sells a pre-built module.

http://vats.likeabigdog.com/

[Hot Pocket]

thanks BDR. I found this

I'll try to wire this together tomorrow and i'll post my results.

[Hot Pocket]

Ok, so we made the circuit in the diagram and there has been some progress, but we aren't quite where we want to be.

Before we made the circuit, the motor would not turn over at all. With the circuit wired into the VATS relay, it will crank and run, but it will immediately die within one or two cycles of the motor.

Thoughts?

edit: and I put a voltmeter up to the ECM output wire, and got the proper volt reading from it, so I know the ECM is not faulty. I'm going to double check my circuitry.

[mudtoy67]

From my understanding, the VATS disables the fuel pump, not the starter, so you're initial no start problem must have been something else. When you first turn the key on, the fuel pump will prime the system. Once you start and the VATS does not see the correct signal, it will not turn on the fuel pump for "run". That is the reason it runs for a second and dies...you're running on the initial prime. The computer is looking for a frequency, not a voltage, so you need to find a way to check the frequency of the signal your circuit puts out. Also, if you're seeing voltage, I'm thinking you've built it wrong:

http://home.hiwaay.net/~davida1/passkey.htm

Tis PASSkey II signal is a square-wave pulsed-ground.

[Hot Pocket]

BDR-
From what I've read, on this car the VATS disables both the fuel pump and the starter. I know that the VATS module was faulty because before we replaced it with out homemade chip, the car would not crank at all. I know that this was the initial problem because the "security" light on the dash gave every indication that it was the VATS module that was faulty. When I turn the key to "on" I can hear the fuel pump being primed. I have checked the relay, and the fuel pump was recently replaced.

Also, when I said the ECM output wire, I did not meant the wire on my homemade chip. I meant the wire that the ECM output connects to. I have read that in order to check the proper functionality of the ECM, this wire should have a voltage reading between 4.5-5 volts... and it does. I have checked the frequency output of everything on my circuit with a multimeter, and I have hit a roadblock.

[TdmayfieldIV]

Run a jumper wire from the battery to the fuel pump so you can take it somewhere to do it right?

[Hot Pocket]

Run a jumper wire from the battery to the fuel pump so you can take it somewhere to do it right?

I'll try the jumper to the fuel relay. As far as taking it somewhere to do it right,

[robertf03]

whatever you are working on is probably too new for that 555 timer crap to work. You mentioned a programmer was too expensive, assuming one exists then you are SOL.

[Hot Pocket]

it's a 95 buick regal.