Michael Droze

Hello everyone. I really need to get to work and my 1990 l98 is not cooperating. I insert the key in the ignition and turn it and nothing happens (except the dash lights come on) For starters, I don't see a security light. Does a 1990 have a security light and if so where is it? So I go up underneath of the dash to the start enable relay, and run a sheetrock screw through two of the wires thereby shorting them together. Presto. The motor turns over now except it will not catch without starter fluid. This tells me that I have no injector pulse. The combination of no start enable relay and no injector pulse tells me VATS. I cut the two wires going from the ignition cylinder to the CCM and with the key in the ignition I ohmed out the ignition cylinder side and saw the key resistance. I then checked continuity on the CCM side, so I know the CCM is seeing the key resistance. I then ohmed out the dark blue wire from the CCM to the ECM which also tested good. Besides a factory service manual what am I missing? Please I'm desperate does anyone have a circuit description and good schematic for the Vats in a 1990 Corvette?

1993C4LT1

Well yeah, a VATS problem will disable the injectors from firing. It does have a security light. Which is to the left of the instrument cluster, lower side. I would just bypass VATS.

Michael Droze

I actually bought a Baker Electronics square wave generator type of bypass. Hooked to power, ground and the blue wire going into the ECM and still nothing. And the ECM was bought the last VATS episode, a year ago. That turned out to be the airbag fuse.....oops.
I know I'm missing something but what??

Michael Droze

I also checked all fuses and fusible links.

confab

Someone said this is a 90?

https://www.corvetteforum.com/forums...-download.html

Michael Droze

Yes it is

Michael Droze

Rebuilt the 700R4 a month after I got it, and have done the head gaskets, a water pump, alternator and battery over the last 5 years. It's nowhere near as fast as my '78, but it's all I have to drive currently, and I've got a ton of great memories in it. And hours under it

Michael Droze

Thanks for the link. Just what I needed.