1991_RS

Swapped a 91 Z28 5.7 TPI into a 89 Firebird (was 5.0 Throttle Body). Car ran before swap. Now, getting nothing when turning key.

Details of swap:

• Swapped entire engine, ECM, & harness (spiced into TBI firewall connector below brake booster).
• Both cars were 700R4 trans.
• Most accessories work after swap, including fuel pump prime @ key on.
• Re-rested key to verify VATS resistor is good.

We are not getting 12v at the gear selector switch when "cranking" the key. Is the VATS module that decodes the key part of the car (ie. in a harness that stays inside the dash) or is it part of the ECM (meaning I need a different key blank)?

Or, is it possible it's something else entirely?

Working on it now, so any advice ASAP would be greatly appreciated!

vetteoz

iTrader: (13)

https://www.thirdgen.org/vats_passkey_system

Module under dash reads the key ; operates the starter enable relay and sends a signal to the ECM to pulse the injectors

Have you got power on starter circuit out of the Ign switch , the starter relay ?

Tuned Performance

iTrader: (92)

https://www.facebook.com/photo.php?f...type=3&theater

1991_RS

Thank you, Oz!So what you're saying is that I can change ECMs all day and they will all work with my key, provided I don't change the VATS decoder module under the dash, right? Is there a way to see with a multi-meter that I'm getting some type of signal from the VATS blue wire at the ECM?


We haven't checked it yet. We did manage to verify that we have spark when the key is in the "RUN" position (starter fluid + jumped the starter = ~1 sec of run time). This will be the next thing we check when we have time (might be a day or two). That will be next on our list to try.

Any suggestions on the connector that goes from the giant harness & ECM plugs to the one under the dash by the VSS Buffer (white, double, lettered A-R, but skips i, o, & q). I traced the wires on both harnesses and created my own pinout. There were a couple differences and 2 wires that the car wasn't "expecting to see".

One other quick question: I've been looking & searching to see if I need to repin the ALDL due to the swap. My friend (a licensed mechanic) used his scanner to try and read the codes (if any), but it wouldn't recognize the ALDL. This wasn't a Autozone economy scanner, but a $1,000+ real scanner from a mechanic's tool company. I thought I saw something once on TGO about it but can't find anything now.

Tuned Performance

iTrader: (92)

If your using the 1227730 ECM it will expect to see a 4k ppm form the vss directly. The tbi used a 2k signal to the buffer. Two was too correct this. One get a new 4k vss and rewire and use the 730 internal buffer or reprogram the tpi Memcal and use the buffer optical signal and use b10 of the ecm. The vats signal from the pass key ont the blue wire is 30hz 50-60%.

dont expect too see much if you are using a mt2500 or a paperclip with out the engine running.

Tuned Performance

iTrader: (92)

acdelco 213-197 or standard motor products sc12. You might want to double check the numbers but it looks like thats the 700r4 4,000 pulse per mile sensor.

http://www.ebay.com/itm/SC12-Speed-S...ce1d31&vxp=mtr