frnkrizzo

1987 Corvette, manual.

I have the random, no start, no crank issue.
After I leave it alone for 15 minutes, it starts up

The key resistor issue has been bypassed.
Still had the random, no start, no crank issue.

Just changed the Starter Relay behind the radio panel. Started right after install, but next day got in and still have random, no start, no crank issue.

I believe there is only one other VATS issue it could be ?
The Cranking Fuel Enable signal. ?????
Would this cause the same no start, no crank issue. ???

If so, could someone describe the fix to me, or point me in the right direction ?

Bob

billschroeder5842

Tell us what your "security" light is doing on your DIC. Is it steady all the time, does it blink on/off or is there nothing?

This can tell us what the VATS is thinking.

frnkrizzo

I think it was blinking.

WVZR-1

You haven't mentioned the clutch safety switch. If you're confident that the resistance bypass is done effectively I'd be inclined to start there if the starter enable relay is good. If you've the FSM there's certainly procedures outlined for diagnostics.

If you don't have the FSM (Factory Service Manual) I'd suggest you buy one.

The resistance bypass was done why?

There's a difference in NO START and NO CRANK, you have intermittent NO CRANK or you have intermittent CRANK NO START?

frnkrizzo

I have a key with no resistor on it and it works fine. A mechanic did it years ago, cant remember why. Think I might had had the Key Resistor issue.

Never checked the clutch safety switch, didn't realize that it could be the source.

To clarify, Intermittently, I put the key in the ignition, everything lights up as usual, but when I turn to start, nothing happens. No clicking, no dimming of the lights, nothing.

frnkrizzo

Since it does not crank after a few minutes of waiting, but Does crank after 15 minutes, doesn't that point to a VATS issue ?

Bob

WVZR-1

Possibly - perhaps the actual VATS DECODER MODULE (key reader) has failed or has issues. I always thought that when it failed there wasn't "intermittent" - I've replaced one many years ago and I believe it was just something I was asked to do. I'd say much depends on how yours was bypassed, if yours was bypassed just using a simple solder of a resistor at the column base perhaps you check there for the resistor, check the resistor value using the stripes (since yours is intermittent) and replace. If it was a bypass of other than just a simple resistor then it would be more complicated.

Have you ever looked for the resistor at the column base?

Does the clutch switch work as expected? EVERYTIME? Maybe you bypass (jumper) it for diagnostics.

Most of the modules I see on eBay even the ones that mention a KEY CODE ain't actually KEY DECODER MODULES.

You might consider looking further into your issues. I'd be sure that if you consider buying you make sure it's pinned like this in one of Cliff's posts.

https://www.corvetteforum.com/forums...post1581212461

Security light has nothing to do with your issue.

You didn't mention having the FSM. Do you?

frnkrizzo

I believe that the mechanic replaced the ignition with a non-VATS ignition (Is that possible) ? It isn't a hot starter issue. I suppose I could check the Clutch Switch. I would have to wait for the no crank issue to happen, and then quickly do that test. Is it easy to do ? Do you have a link somewhere that described how to check the Clutch Switch ?

I don'r have the FSM.

I have seen where people have a chip made to totally bypass the VATS. Is that an option ?

I do have a performance chip in it now.

WVZR-1

NO - not an option.

Clutch switch as well as resistance required for crank generally either work or don't. A 15 minute wait for clutch switch is a NO. A simple check of clutch switch might be KEY TO CRANK (1st) then depress clutch occasionally to see if it enables CRANK. You need to be sure that the CLUTCH SWITCH isn't bypassed also, use neutral with no one or nothing close. In the link I provided you for the module I've no idea how the usual 4 minute delay to reset is controlled.

The FSM might be a wise buy.

Cliff Harris

The delay is done by the VATS module. Don't try to start it over and over again and make sure to wait at least 5 minutes. Each time you try and fail it resets the delay timer.

hcbph

If your security light is blinking, yes I believe you have something going on with the VATS system. IIRC if you have a VATS start failure (typically due to either the resistor or clutch switch failure, it's about a 15 minute reset).

The easily accessible items are the clutch switch and the key resistor.
The key resistor can be overridden by using a dongle. This is overridden by disconnecting the twin wire connector coming from the column (1 wire is orange IIRC) and at the connector disconnect it and plug the correct dongle into the end going up behind the DIC. The clutch switch is up by the pivot on the clutch pedal. Unhook the connector and jumper the wiring connector.

At this point you've overridden both of the 'usual' issues. When you enter the car and turn the key on the Security light should be out. If it's on you have some other issue going on. If it's out, when you should hear the fuel pump run for a few seconds once the key is turned on. You should be able to then start the car if all else is working.

I have read where others have bypassed the remaining items in the VATS system but I do not have any info on that procedure.

Good luck.

WVZR-1

I understand it's done in the module - I just don't know which aspect of the module "IS THE TIMER"! OP seems to imply that if the car is started and shut off it won't crank immediately.

If the OP's failure is an EVERY TIME occurrence then maybe there's a component in the module responsible. Not knowing how the OP's mechanic did the by-pass it's difficult to speculate. He needs to look.

I've never used a bypass for anything but diagnostics(I have an Interrogator) but perhaps if maybe one of the New Rockies or other similar was used it's that module that's failed. I've never had a hands on or seen the install instructions. I've seen 555-timer VATS module builds mentioned but never used one, I always thought that when you used one of those you actually bypassed the SER so you would have CRANK any time key was rotated.

WVZR-1

I don't believe "CRANK RELATED", VATS (Vehicle Anti Theft System - YES) BUT I'm reasonably sure that it (SECURITY LIGHT) is only a component of the forced entry for early C4.

rblakeney

I would start simply by checking that both battery terminals are clean and tight. I had the exact same problem on my 89 and it was a loose dirty positive terminal bolt. Was allowing just enough current to turn on the dash but nothing else. A pair of new terminal bolts were a few bucks.

frnkrizzo

The No Crank issue is very intermittent.
Battery terminals are brand new and tight.
Security Light is on when it wont crank.
Key is bypassed.
Starter relay replaced.

hcbph

You are correct, I should have said security instead of Vats here. I had some issues with mine when I bought it. One was apparently it wasn't reading the resistor on the key all the time (figured that out later), when you turned the key on the Security light was flashing and the starter wouldn't engage. Once I put a resistor dongle on the car that part of the issue went away.

frnkrizzo

What is the Vehicle Anti Theft System Module ? I see them for sale on ebay. Could that be the issue ? Also, is the a way to check and see if the key bypass is working ? Still stuck here with intermittent no-crank.