Scott Garner

Subtitle: How to completely bypass VATS and PASSKEY for $20.

I've already implemented the workaround, and I'm posting this as a reference for the internet, because I searched and could not find my very specific problem set, with a proper explanation and the workaround fully documented. My hat's off to the guy at https://vatssucks.wordpress.com/, but with all due respect, he stops short of the real bypass and only recommends an ECM reprogram. There is a much cheaper, quicker, and easier way...

1989 Convertible L98 w/electronic door locks

Symptoms

• Turn ign key, dash lights up fine, no crank
• Non-ignition key anti-theft features work normally (arming, disarming via door locks)
• Security indicator lamp does all the normal things when ign key is not present
• Security indicator lamp goes out immediately when ign key turned turned to On
• Security indicator lamp blinks when ign key turned to Start (and of course, there is no cranking at the engine)

Note: there has already been installed and working for a while, the "VATS bypass" resistor between the ign lock cylinder and PASSKEY module. This little workaround is commonly called "VATS bypass" and, as I've learned, it's really only a partial VATS bypass. There's more to VATS than just the resistor pellet in the ign key.

Troubleshooting
According to the FSM, when the ign key is turned to ON, the security indicator lamp should go solid for two seconds before going out. This was not happening. It would do its normal blinking/solid/off routine for the arming/disarming of the anti-tamper alarm that is governed by door locks and hood/hatch releases, etc. But as soon as the ign key was turned to ON, the light went out. When turned to Start, instead of the engine cranking, the security light blinks. This was the behavior that I searched for, and while I found one or two other reports of this, I didn't see any resolutions. I'm not saying no one answered the question, just that I couldn't find it, and hence, this write-up. The FSM instructs to do the "Security Indicator Voltage Test" (8A-133-14), which is testing for battery voltage in the dark green (#4) wire, and if it's present (it was), then it stops here and says replace the PASSKEY module.

I took the PASSKEY module out of it's little plastic house and really looked for any visual signs of problems, and there were none. I'm used to seeing problems with PCBs and have found and fixed a lot of them, e.g. cold solder joints in the electronic dash and climate control modules, burned resistors, leaky caps, etc. The two major online parts suppliers that I use both sell this thing for about $350, but neither have it in stock.

Note: jumping the VATS starter relay does allow the engine to crank with the key, but it won't start (because the fuel injectors are not operating, because the ECU is not seeing OK signal from PASSKEY).

Workaround
I don't call it a "fix" because it doesn't fix anything. But it will completely bypass and disable VATS, at least as it relates to ign key stuff.

• Go on Amazon and search for "VATS PASSKEY module." ~$20 shipped. This little guy will deliver that particular 5v 30hz signal that the ECU needs before it allows the fuel injectors to pulse during the start process.
  • Your PASSKEY module is behind the "breadbox". Find it and unplug it.
  • From the PASSKEY connector, jump red to bypass red, black to bypass black and bypass blue, dark blue to bypass white
    • bypass red needs ign voltage
    • bypass black is ground
    • bypass white is the special signal the ECU needs
    • bypass blue and green: these determine the mode. To get the signal you need, ground the blue wire and clip or tape-off the green.
• Unplug the starter relay behind the multi-use panel in the dash. From the connector, jump the outer yellow and green wires (#1 and #5).
• I'm not sure if the resistor at the ign cylinder needs to be installed at this point, but I already had it in there, so I left it. I don't think it needs to be there, though.
• The resistor in the key or the lock cylinder is no longer necessary. You could use a pellet-less blank as long as it's correctly cut and turns the lock cylinder.
• I haven't done this yet, but it's probably not a terrible idea to have a "kill switch" that would allow you to manually enable VATS. Maybe put on the red wire?

GM VATS PASSKEY Bypass, ~$20 on Amazon



Behind the breadbox, PASSKEY and starter relay bypassed

RalfKramden

A question. I bought this awhile ago but haven't installed it yet due to other projects in the way for now. You unplug and leave unplugged the connector for the

PASSKEY module? Then you connect the wiring as per the instructions? Just want to pin it down. I also have the resistor that will match my key so I'll install

that as well (belt & suspenders kind of guy).

Scott Garner

That’s right. Leave PASSKEY module unplugged after you install the bypass. If you think of it, do this part first, then disconnect the wires that read the resistor off the key, and see if it all works.. I’m curious about that.

RalfKramden

Ok, Thanks and I'll try that first. I *think* that the resistor bypass will be unnecessary but we'll see. Probably get on it in about 2 weeks.

RalfKramden

Ok Scott, just installed the bypass and left the pellet wires uplugged and the car started no problem. So if you install this, the resistor bypass is not necessary

Tim

Doctorbatman

I love this thread.
I too would love the bypass AKA replace the VATS module but haven't found on that lists it will work with a 1986 model year.
Does anyone have an idea where I could buy one?

Thanks,

Doc

Scott Garner

Thank you for checking back in with that!

Scott Garner

It's my understanding the VATS/PASSKEY system in these cars is unchanged from 1986 - 1989. If that is indeed the case, you should be able to use the same device I used. On Amazon, search for "VATS PASSKEY module" and it should come up. I put a little picture of it in the first message in this thread.

KTLarry

Scott gets a big thumbs up for his detailed description of his successful VATS disabling process. Another thumbs up is in order for providing similar supporting info on Amazon. Great job Scott!