My father and I recently installed a brand new 1985-89 TPI wiring harness from Painless Performance (#60102) and have been having some issues getting the car to start and we think it might be the VATS system. The car was originally a 92 which is why it has the VATS in the first place, but, since 85-89 cars didnt have VATS, the wiring harness we ordered to match the computer in the car (which was from an 88) doesnt have the wires to hook it up, which we think is what is keeping us from starting the car. Heres a few questions: 1) Does this sound plausible as a culprit? 2) If the car has an 88 computer, was the computer just bypassing the VATS unit before the engine wiring was replaced? and 3) the harness came with 1 purple wire labelled VATS which I was told to hook up to the purple wiring coming from the steering column for the lock cylinder, why would we need to hook this up?

 

The VATS performed two functions to disable the car as I understand it. 1) it provided a ground for the Starter Enable Relay, and 2) it disabled the fuel injection power (IIRC). This way, when the VATS didn't get the right resistance, car would not start, and wouldn't run if starter was straight-wired under the hood or under the column.

The ignition half of the equation is easy to bypass - simply provide a ground for the Starter Enable Relay. Its the fuel half of the equation that is more difficult.

There is a VATS module - I read it's located up under the dash, driver side, but colser to center of car, and buried deep up there.

Have you removed this module all together?

The VATS didn't really have anything to do with the actual ECM (computer). You could in theory have any year "chip" plugged into the slot so-to-speak. The VATS disabled by simply not allowing a ground connection (or maybe a power connection) to one of the wires running into the ECM box itself - and it would have to be one of the wires that had to deal with the fuel injectors firing (again, if I am right about the second half being fuel injector disabling). In my theory here, whatever "chip" you had installed got the required grounds and power it needed - it "knows" nothing about VATS and doesn't have to, it just needs it's power/grounds sources and it's a happy camper

Looking at this wiring diag: http://www.austinthirdgen.org/mkport...m_pass-key.jpg

I'm wondering if you grounded the dk blue wire 229 (upper right of page) would that solve the fuel issue? I'm certainly no expert at reading diagrams! Maybe you can look at it and figure out how best to proceed.

I'd sure like to know what you come up with! Good luck!

 

The problem appears to have been solved and, I'm sorry to say it, but the guys from painless were wrong. The harness they provided attempted to bypass the VATS system all together by hooking up the lock cylinder straight to the computer, I'm guessing like the earlier TPI models were set up. Unfortunately, if the VATS module is in the car, you cannot bypass it like that. It was a pretty simple fix but the car runs now thanks for you help.