adestoy

I've got a '90 Convertible. The VAT system has left me stranded a few times. The guy I bought it from had been stranded MANY times and ended up installing a Viper remote start system with the proper resistor to trick the VAT into thinking a key was in the ignition.

So, since the VAT is in essence already bypassed, I'm looking for answers.

First, I heard today about a place up in Michigan that will "burn out" the portion of the CCM to allow the car to always start. Sounds dangerous... Has anyone else heard of this?

Second, looking through the manual (1990 Corvette Section 8A - Electrical Diagnosis Service Manual Supplement - ST-364-90 EDM) It shows that the start enable and fuel enable leads are simply shorted to ground to enable. If I short these two leads to ground and the car starts, this should tell me I have problems with the VAT system and not the UTD system, shouldn't it? I only say this because the power door locks haven't worked for at least two years, (actually among other things) and it's a part of the troubleshooting charts.

HELP!!!

jfb

The VATS module measures the value of resistance in the pellet on your ignition key and if it is more than 5% from the stored value, VATS tells the CCM to not pulse the injectors and it won't close the start enable relay preventing the starter motor from cranking. In series with the start enable relay is the clutch safety switch (gear selector sw if an automatic) and if this switch is defective, the starter will not crank and you should try bypassing the switch and try a crank again. There are contacts in the ign sw tumbler that make connection to the pellet and these eventually wear and become unreliable. You can test these contacts by removing the hush panel above the driver's feet and finding the two wires (white on my 87) from the steering column that go to a 2 pin connector. Unplug the connector, put your key in the ignition and measure the resistance across the wires from the column. It should measure the same as the pellet. If over 13k ohms, you need to replace the ignition tumbler which has new contacts. It is a bad idea to bypass VATS permanently because 99% of thefts are done by bashing the column and jumping the ignition. I have driven my 87 vette every day since 1989 and I have replaced my ign tumbler once and since then (about 10 years ago) it has started every time.
Why anyone would want to install a different system in place of the VATS system is a deep dark mystery to me. It would be cheaper to just repair your VATS !!!!!

waynesTPI

burned out of my eprom. I believe in only getting left startless, due to a system such as this, once. I had my once and it was at real bad time when my other ride was down for maintance. JMHO
Besides my current VATS works just fine, my dog, my 1911, and the combat infantry license plate that reads PTSD.

steve1ph2

hi, i by passed my vatts some years ago but cant really remember all the details. it goes somthing like this the vatts ohms read like from 1 to 13 or 14 with each number representing a diffrent value. i remember going to radio shack and buying a variable resistor. i completely pulled both wires off the ignition and attached them the the terminals on the resistor and ohm meter then dialed in the factory values 1-14 one at time while trying to start the car at each value. it turns out my car started around 12 or 13 but i cant remember the value. so at that point i used some super glue on the dial of the resistor so it wouldnt ever move. taped up the wires done. not to get stranded again. you should do a search on the net for the gm vatts codes so you will know how to set the meter for the resistor. you know i think im getting confused? not really but i did get all that off the net and it worked for me. the other post is true as well why bypass cause a thief cannot start the car with out the right key with the right resistor value stored in the ecm. it aint going to happen. what i did for securitiy after that was install a kill switch. but dont run it off the starter to easy. i ran mine off the negitive side of the distributer. good luck

adestoy

The Viper security system HAS the resistor. When neither the key nor the remote start works, the problem has to lie elsewhere. My intention is NOT to bypass the VAT system. only to troubleshoot it. My intention is to install a short to ground on 625 (BLK/YEL) and 229 (DK BLU) and see if the car will start. If it does, the VAT is what is keeping the car from starting. If not, I look elsewhere.

Even if the VAT is bypassed, I still have a security system, but I do intend to keep the VAT system.

adestoy

WaynesTPI... My dog is worthless, I don't have a concealed carry yet, I have a few friends in the millitary, I have to count on an alarm. Unfortunately, you can't steal my car WITH the key!!! Oh well...