I've got a 87, and it won't start every now and then. It won't even try to start. But if I try to start it after about 5 min afterwards then it will usally start. It's a very intermittent problem, I'll go weeks without it happening, but sometimes it happens a few times a day. Both in hot or cold weather. I was told to change the starter solenoid, but it didn't help at all. I'll be very appreciative if anyone can help. Thanx!

 

VATS measures the pellet resistance and if it exceeds 5% error from the stored value, won't allow a crank nor the injectors to pulse (so the car can't be push started) and makes you wait 6 minutes to try again. With a new ign tumbler which has new contacts that connect to the pellet, I would recommend you try your spare key as its pellet contacts won't be as worn. Next, there is a clutch safety switch (gear selector switch if automatic) that, if defective, won't allow a crank. Next time it won't crank, bypass the clutch safety switch and measure the voltage to ground on the bypass. If you measure 12v in crank position, then you have starter or battery connection problems (clean your battery cables and battery terminals). If you don't have 12v, then VATS is involved. Pull the hush panel above drivers feet and find the 2 wires from behind the steering column (white on my 87) that go to a 2 pin connector. Unplug and measure the resistance across the wires from the steering column with the key inserted. You should measure the pellet resistance. If over 13k ohms, you have a bad ign tumbler. If ok, then you might have a defective start enable relay or VATS module. You can temporarily bypass VATS by connecting a fixed resistor across the 2 wires that go into the wiring harness (these go to the VATS module). You can use a 1/4 watt 5% resistor from Radio Shack. Don't permanently bypass VATS because 99% of thefts are done by bashing the column and jumping the ignition.

 

jfb, I've probably seen you post the same response 20 times since I've been a member I wonder if it's not time to post a sticky on top? Something like-"Vette only starts after waiting 5 minutes or so".

 

I don't mind posting it. When your car won't start you get pretty anxious and looking for a quick answer is what you are after and spending time using the search function or finding a list of common C4 problems just doesn't come to mind right away. I've had a few members thank me for the info and that's enough for me!

 

Well jfb, you have my thanks, and for it's worth, I printed of your response along time ago and put it in my corvette book I've been assembling.I try to do this with what I consider valuable information.

 

Next time it does this take note of the security light. If it is on then it is VATS related, if it isn't on...give the starter a whack or 2 with a hammer and try it again. Since you replaced the solenoid and got no help, the starter commutator ay have a flat spot on it that lines up just right sometimes and prevents power from getting to the armature.

 

My dad helped me do the bypass. $.06 worth of 3 resistors, 2 mins of soldering and heat shrink and I was back in business every time after that. I think my lock column went bad on mine... now I will never have to worry about it again (unless the VATS itself eventually dies i guess, knock on wood) Entire project took 30 mins.... oh and nobody steals C4's anymore ...plus thats what insurance is for heh

 

I don't believe there is any connection from the VATS to the Security light on an '87. The Security light is driven soley by the UTDS. Can anyone confirm?