I did the VATS bypass by basically sticking the resistor in the connector, and the car started fine.

when I got home, I wanted to make this more permanent so I cut the wires and soldered the resistor to the connector, similar to this:



before plugging this into the vats module, I measured the resistance and I get the correct reading 1450 ohms. I plugged the connector into the vats module, and now the car doesn't crank.. the security light is not on, but the car doesn't crank now. any ideas what went wrong?

when I measure the resistance on the wires when it's plugged into the vats module, I get no reading. shouldn't I still get a reading of 1450 ohms when its connected?

 

Yes, the connections between the connectors might be bad. Make sure you have it plugged into the harness going to the module and not to the key switch!

 

Did you ever fix it?
Cut the wrong wires?

 

i thought vats was the two white tiny white wires inside the orange sheath anyway you changed the resistance wen you soldered it and by the way there are several versionsof vats passlock and passkey and some like 95 road masters use the chip key combined with the halleffect likepasslock and its a blue wire pin 11 on bcm you haveto puls width modulate a signal on that wire. You can ground it un ground it like 3times otherwise it will crank and cut fuel so its important to identify which system you have as all of them are a little different

 

Sorry but your description is misleading in several ways. The Passkey versions of VATS in GM vehicles (the ones with resistors in the keys) are always the same in terms of a resistor bypass. There are 15 different resistor values used in the keys (only 14 of them were ever used in f-bodies) and those 15 values are the same across all brands and models of GM vehicles. PWM (Pulse Width Modulation) is not used in the VATS resistor circuit but it is used in the signal between the BCM (Body Control Module) and the fuel enable input on the PCM (Powertrain Control Module) - that would be the dark blue wire at pin 30 in the red connector of an f-body PCM. But that is completely unimportant to a VATS bypass. Installing the correct resistance value across the sensor wires (which are white in the steering column but white/black and purple/white in the dash harness) is quite sufficient to bypass VATS by fooling it into recognizing the correct key resistance value as always present. Various minor differences in implementation between vehicle models and years have no impact on the effectiveness of a resistor bypass.

Passlock is a different system which does not have a resistor in the key and as such can't be bypassed in this manner. Instead, Passlock uses a sensor next to the ignition lock cylinder which detects the rotation of the cylinder (this is the Hall Effect you mentioned). The theory was that thieves would normally use a slide hammer to pull out the ignition cylinder which would prevent the sensor from seeing the rotation. But that system was never used on any of the vehicle models or years that are commonly discussed in these forums. And the 93-96 Buick Roadmaster used a standard Passkey system with key resistor and not the later Passlock version with the lock cylinder sensor.

There are two ways to bypass VATS... the resistor method is the most common but you can also tune the PCM to ignore the lack of a fuel enable signal as long as you provide an alternate ground for the coil side of the starter relay since that can't be changed in programming. The BCM is not programmable so you can't just "tune out" VATS.

Oh yeah, and soldering a connection does not change the resistance unless it's done very badly (i.e. with the two conductors not directly touching each other). Besides, the tolerance is quite wide so that wouldn't cause the bypass to fail.