Can some one confirm the frequency of signal sent from the TDM to the ECU on the 1989 Firebird I've seen both 30HZ and 50HZ on a 0/5 volt square wave with a 50% duty cycle. I don't have an oscilloscope to verify.

Same question for the signal sent from the BCM to the PCM on a 2000 firebird.

The reason I ask is I want to make the VATS work in my LS1 swap. It seems the PCM can be reprogrammed with the minimum and maximum frequency, thus allowing it to work with the 1989 VATS system.

I've googled and searched these forms but the answers varies so I'm trying to get a solid I know this for a fact response here. I don't want to build a bypass box or rig in a resistor, both the 89 and the donor car's vats works and I have the keys. I just don't want to have to wire in the BCM from the 2000 if I can avoid it. And yes I know I can have the VATS disabled in the PCM but I would like to actually make the systems compatible.

 

You might want to ask this seller.
https://m.ebay.com/itm/GM-VATS-or-PA...gAAOSw3fZZ6JWY

 

If you don’t have a good com this one works great. You can measure the hz signal.
https://m.ebay.com/itm/Fluke-78-Auto...oAAOSwHUhZ82hT

 

30 Hz.

RBob.

 

Thanks RBob -- so I would either need to reprogram the PCM to accept the lower range in the 2000 computer or use the BCM from the 2000-- I have keys and keyfobs from the 2000 so its tempting to do so.