I purchased a 1990 Vette about a month ago & have an aggrivating problem - an intermitent no start situation. I have replaced the key cylinder and got a new key. Every 10 or 15 outings, the car fails to start (after I have already left the house). The battery is fine - when I turn the key on there is power, the starter wont energize when the key is turned to the start position. If I leave it overnight and come back the next day, it starts right up. Is there another component to the VATS system that energizes the starter and fuel injectors that could be bad? Maybe the ECM? I had to leave it at a car wash today and bum a ride home. Any help would be greatly appreciated.

 

Have you tried the "Search This Thread" option? Try looking there for VATS.

 

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 printed this information from another post that you answered and I wil try it, but I thought that by installing a new tumbler & key (parts straight from my lacal Chevy dealer - Genuine GM) I would have eliminated the need for the "Radio Shack Fix". I heeded your advice on the Corvette Theft warning and decided that I didn't want to permanantly bypass the VATS. Where is the starter disable relay and VATS Module. I am ready to just replace them both and see if that fixes the situation. I don't mind buying the parts. Also, could it be the CCM (main computer) & where is it located? I am going to town to try it again here in a little bit (I live on a ranch 10 miles from town).

 

I recommend that you follow my diagnosis instructions and find what the cause is and then replace the defective component which will be a lot cheaper and with a lot less labor! I can tell you where the start enable relay and VATS module is on an 87 since I own one, and they are probably in the same place on your 90, but I might be wrong. The start enable relay is behind the middle of the dash in an open plastic box called the multi use center and the VATS module is behind the instrument panel on the RH side near the fuse block. The ECM (on an 87) is on the RH side of the dash near the fuse block and is accessed by removing the hush panel above the passengers feet. Be mindfull that the VATS function may have been included in the ECM in 90, I don't know, but the thing for you to do is to go through the diagnosis I outlined and save yourself some time effort and money! Good luck.

 

Thanks JFB. I'll tinker on it today and see what I can find. I appreciate your time & patience!

 

Well, I tried it again last night and it still wouldn't start. It wasn't where I could work on it so I left it there. Went back this morning and it started right up. I'll have to keep driving it until I can make it do it again, then run the tests on it. I will keep the forum posted as to what fixes it. Thanks!

 

I sent the vette into an electronics shop to remove the aftermarket alarm/remote start. Hopefully the problem lies in that. We will see.

 

I tried everything to start my 88 auto. but still nothing, got the bypass installed & nothing,looks like it maybe the start. disable relay or vats module ,where can I get these & are they expensive???

 

Is this happening to you on HOT starts? If so, it may be your starter. My 87 vert had that problem. It would act up when the motor was hot. If I would let it sit and cool down it would start right up. Put in a good mini-starter and it fires up all the time.

 

Same here on my 87. I thought it was VATS but my tech told me to try different keys and if it happened with both it was most likely NOT a VATS problem. I replaced my started and the problem disappeared.

 

If I leave it overnight and come back the next day, it starts right up. thats what puzzles me. iv had problems with the vats. seems most of the time for me it did not matter if i left it over night or what ever at any time if the iginition could not read the pellet on the key it would not start. nobody suggested to wipe or abraise the pellet lightly and try again. the first time i did that and it started i did the "radio shack" trick and got an after market alarm. i really dont know much but im with the other responder i kinda dont think its a vats problem so keep an open mind..

 

Resistor bypass mod. 'Nuff said.

 

If one has the resistor bypass mod. already (more than 5 yrs now) , now the car doesn't want to start intermittently then it would be either the starter relay or VATS issue and not the igniction tumbler correct?

 

I installed that & nada,also I have a lift & put car on it& jumped the starter& it works, it runs for 3 seconds & shuts off,its definitely vats ,so my ? is where to get those 2 parts??

 

Starter circuit: If VATS sees the correct pellet resistance it closes the start enable relay. Current to the starter solenoid comes from the battery through a fuseable link, through the firewall connector, to the ignition switch, to the start enable relay contact, to the clutch safety switch (gear selector switch if auto), through the firewall connector, and then to the starter solenoid terminal on the starter. According to my instructions above, if you jump the clutch safety switch and measure the voltage on the jumper and find 12v with the ign sw in crank position, then most likely you have a starter or battery cable connection problem (but it still could be the firewall connector). If you don't measure 12v, then VATS didn't measure the correct resistance, start enable relay is defective, or the VATS module is defective, ign sw is defective, fuseable link is defective, or the firewall connector is defective.
If you don't get 12v on the clutch sw jumper in crank position, then hold the crank position and check for 12v from the battery to the ign sw, on both contacts on the start enable relay and then on the starter solenoid contact on the starter. If 12v is on the starter, then check for poor battery connections, poor large cable connection on the starter, or a discharged or end of life battery.

 

Well, it looks as if my no-start problem on my 1990 Vert has been cured. I have a feeling that I had a weak starter relay (under the Pass side kick panel). I called Gordon Killebrew and he told me to short the Black wire with Yellow stripe coming from the Starter Relay to the dash frame. So I scotch locked a wire to the Black/Yellow and grounded it to the dash frame (I also replaced the Relay). This makes sure that the starter turns no matter what when the key is turned (Your VATS still must match to enable the fuel delivery system). This is the longest I have gone since I have owned the car - 2 months - that I have not had a no-start problem. I have spent the last week driving my Vette everywhere to run errands to test the fix - and it appears to have worked. I am still a little weary, but getting more confident.

 

The starter enable relay is about $20 from the dealer. A GM shop manual has an excellent set of troubleshooting charts for the no start deal, that would be of tremendous help to you. You'd be able to check the starter enable relay itself and know for sure what the problem is. If I had a place to host PDF files I'd post it here for you, but I don't.

This place also carries the starter enable relay if you find it the source of the problem in your case.
http://www.artscorvetteparts.com/par...a-7e22596c66e9

 

I bought my starter relay at NAPA for $9

 

which did you buy, starter relay or starter enable relay??