Hey guys, newbie here. Got a 89 IROC w/ 5.7L and a 5 speed. Car wont start. Just bought it off a buddy with "legal" troubles. Anyway I used to own this car a few years ago and had some starting issues before. turned out to be the pass-key module under dash. Fixed it and it was fine til I sold it . Well since he had it things started happening again. Long story short, he replaced the ECM, the ingition key cyl. with the chip, and sent it to at least 3 differant shops and it still wont start. Right now I turn the key on and I have no security lite. But sometimes the lite comes on and wont go off til I disconnect the power to ECM. Then the lite comes on for a few seconds and goes out, but still no start. I dont know if its the VATS, the pass-key box again or something else. Checked the ign. switch and it does what it should. Hot red wire, hot yellow in start.Thought I would come here and see how good you guys are! LOL. Hopefully you guys can help me out.

 

1) no 5.7 litre motor was offered with a 5 speed - so if this is original, it's a 5.0 litre.
2) the VATS module does two diffferent things - it cuts grounds the starter enable relay so that the starter gets 12v+ from the signal wire (purple wire to starter) and it sends a pulsed wave signal to the ECM to tell it to fire the injectors.
3) If you did a swap to a 5.7 litre motor, you obviously had to swap ECM - if you swapped in an ECM from a non-VATS car, then the injectors should fire (I guess), since the ECM is not keeping the injectors off until it gets that signal from the VATS
4) if you swapped in an ECM from a VATS car, there were some VATS modules that sent out a 30Hz signal and some that sent out a 50Hz signal - if you put a 50Hz VATS ECM into a car with a 30Hz VATS system, then the injectors would not fire
5) I assume you replaced the ignition key with one that has the same identical resistance value in the "pellet" as what the original key had - otherwise the VATS won't work.

If the car is not starting (ie no starter turning), trace the wires in the ignition system to the starter. 12v+ on yellow from ignition switch to starter enable relay, then 12v+ leaves relay on green wire to the neutral safety switch (above clutch pedal in a manual car), then leaves NSS on a purple wire out through firewall to starter. Should get a 12v+ on each of those wires when the key is turned to start. If the problem is with the starter enable relay, you can replace it or simply ground the wire running from it to the VATS module. If it's NSS, then need to replace. Or might have a break in the purple wire between dash and starter.

If the starter turns, but car won't run, then it's obviously an injector issue with the VATS, not a starter enable relay or other ignition wire issue - might have to look into buying a VATS bypass module - they are available for $20 - $60 and they send either/both Hz signals (30Hz or 50Hz) to the ECM so it always gets the signal it's looking for to fire the injectors.

 

Everything on the car says its a 5.7L motor. The badges on the rocker panels, the IROC badge on the rear, and the sticker under the hood. Havent checked the engine ID # yet but everything else says its a 5.7 L. I've tried the resistor thing with the key and still no start. I can get it to crank with a starter button but it still wont start. It sounds like it wants too, but wont fire up. any way to bypass the key AND the starter enable relay? Just want this thing to fire up!

 

Maybe it is a 5.7 litre and a previous owner swapped in a 5 speed then.

In which case you would have an issue - there isn't an ECM available for a 5.7 manual tranny (since GM never produced that combo), and if the ECM was swapped to a accomodate a 5 speed tranny, then there is quite possibly an issue with the VATS module and the ECM.

Sounds to me like you are having VATS signal to ECM issues - and you need to get one of those bypass boxes I mentioned and try that. They are on ebay for $20 I think, and I think Painless and others sell as well but at a higher price.

But understand - it's very easy to get 5.7 badges and slap them on a 5.0 car. What is the 8th digit of the vin - that will tell you what engine was factory in that car.