Have you ever had that sickening feeling of turning the key and nothing happening, not even the gnashing sound of the starter? Welcome to the wonderful world of VATS.

I've now had my 86 (now departed) and 95 both strand me in such a manner.

There are quite a few posts about VATS, but I'm going to try to provide a picture guide for those of us (like me) who are not entirely electrically-savvy. Information was gathered from this forum and from an email from jmccloud.

Troubleshooting included pulling the clutch safety switch out and testing. Also trying to clean the ignition switch and key pellets. And then finally, sticking the key in and seeing if i could see any resistance in the wiring harness. More details on this below.

Step one: Get your multimeter (mine was something like $5 at Harbor Freight) and figure out your key pellet resistance. Mine happened to be 526 ohms. I didn't know how to read my multimeter very well so the first time I went to Radio Shack I got 10k ohm resistors.

Step two: Use this chart to figure out which resistor set you are in. I am in #2.

#
Nominal
Low
High

#1
402
386
438

#2
523
502
564

#3
681
654
728

#4
887
852
942

#5
1130
1085
1195

#6
1470
1411
1549

#7
1870
1795
1965

#8
2370
2275
2485

#9
3010
2890
3150

#10
3740
3590
3910

#11
4750
4560
4960

#12
6040
5798
6302

#13
7500
7200
7820

#14
9530
9149
9931

#15
11800
11328
12292

Step 3: Go to Radio Shack and get some resistors. At $.99 for 5 you can afford to get a bunch if you need to.


I knew from the chart above that I needed to get to something in between 502-564 ohms. So using the info in Step 4 I got some 220 and 330 and then some 10 ohm, just in case. I lucked out, as not all combinations will be that easy.

Step 4. (from jmccloud)
Combine resistors until your multimeter gives the same reading for the resistors as it does for the pellet in the key. Resistors typically have a 10% tolerance on value so you may have to try several different ones of the same rated value to get what you want.
Resistors connected end to end 'add' value. So two 1000 ohm resistors connected end to end would measure 2000 ohms. That's a 'series' connection.
Resistors connected side to side in a 'parallel' connection combine according to the formula A*B/(A+B). So two 1000 ohm resistors connected in parallel would be 1000*1000/(1000+1000) or 1000000/2000=500ohms. Or a 1000 connected in parallel to a 500 would be 1000*500/(1000+500) or 500000/1500=333ohms.
So use several resistors in series or parallel or a combination and you can get the "Nominal" value very accurately.

Step 5: Find the VATS wires. This info is for a 95. Yours may be different.


The white wires with the orange cover are the wires coming from the ignition switch. For trouble shooting I hooked up the multimeter and put the key in the ignition. I got no change on the multimeter.

These are the wires that connect from the wires coming from the ignition switch and go to the VATS box or whatever you want to call that evil thing. That big clump of relays are left over from an aftermarket security system a previous owner had installed. One these days I'm going to rip that @#%% thing out.

Step 6: Testing. I prefer testing as i go along. I'm funny that way. Maybe it's from hanging upside down under the dash for too long.

I took my two resistors (220 and 330) which I had soldered (poorly) together and hooked up alligator clips to the wires going to the VATS box. (At this point we don't care about the wires coming from the ignition switch.)




And the car started for the first time in a week. Phew.

Step 7. Cleaning up the installation. Now I was faced with figuring out how to install the resistors permanently. The connector going to the VATS box was a male and I didn't have a good way to attach the resistors. So I removed the connector cover and soldered the resistors right to the male ends. Hopefully when I restore this car in 20 years I'm able to reverse this.



I covered it with heat shrink tubing and tucked everything carefully up under the dash.

And then I went for a drive.

Total cost:

Tow home: $50
Resistors: $4
Chiropractor visit from cramming under the dash: $7000
Joy of defeating another GM engineer: Priceless

 

Thanks!

 

Good info, the pics really help! Thanks for sharing!

 

Nice tutorial, i'm sure it will help alot of members on here. But imo I would never disable the vats.

 

You say that now, but have you ever been stranded by the VATS?

Although it depends on how risky of a place you live too.

The options were to replace the ignition switch or put an in-line VATS controller that would allow start/disable.

These are all options still for me.

 

Yes I've been stranded by VATS, once, at church. I called my dad, went home and measured my pellet, took some resistors from my workshop and duplicated the resistance. Went back to church and clipped the resistor to the socket and drove it home. I had a new ign tumbler installed which has new contacts and I have been driving my 87 every day since and that was 6 years ago.
The person I bought the 87 from bought a new 90 Vette and one day they got off work to find their driver window busted out and the column smashed, but the Vette hadn't moved an inch. Keep your car in good repair and don't bypass VATS!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!

 

Why not reprogram the chip to disable VATS? Just curious.

 

This is a very well written and nicely documented repair. You should submit it to the " Tech Tips" section. Thank you for posting it.

 

great post!

if anyone has their chip customized in any way, disabling VATS would be as basic as having the fans reprogrammed. i would look at it as a "while you're at it" procedure in a custom chip re-program.

i dislike VATS. it caused me trouble as well. it is archaic, unneccessary, and OBE when it comes to a C4 corvette; no one is going to steal a basic L98/LT1. no need for VATS. just lock your car and that'll be good enough in year 2006 and beyond.

 

VATS tried to leave me stranded a couple times as well. My proceedure was (1) stop at dealership on way home and have them tell me the VATS number. (2) order bypass kit from corvette central for $24 or so. (3) plug it in and forget about it. No problems since. Cost, $24. Time spent, 15 minutes maybe. Worth it to me just to order the thing and plug it in to the factory harness rather than spend the extra time to fab one up myself. Didn't have a multimeter at the time. I don't have any resistors. No place in my little town to buy any.

 

Great info. My 87 did the same thing only luckily after trying to start it after coming out of winter storage in the spring of '04. I used the Helms and found my problem to be a bad VATS control module whick is behind the breadbox. I got a used one from Vette2Vette for around $100. It had been tested by Gordon Killebrew and was guaranteed to work.
And YES - what a great feeling when the car actually starts!
I had also talked with Ski dwn it (Jesse) prior to this and he offered to reprogram my chip to eliminate the VATS along with changing the shift points, adjusting the idle, etc. all for around $200.
When clicked on this thread I expected some fabulous photo gallery with a lot of bells and whistles. Yellow Lust is a Mac guy who works as a designer for a large corporation and can make his Mac dance, sing and shoot off fireworks.
A little disappointed that all we got was plain pics. (just kidding!)
Glad that your yellow bananna is back on the road.

 

That is one way for sure.

 

Geez Ron, I can only do so much with the Forum software. If I have created a whole new web page then no one would find it. Not that it didn't cross my mind...

Why not order the VATS bypass? I could have, but until I did further testing I couldn't discount the clutch safety switch. And by then it was faster to just stick the resistors in. Besides, I get the satisfaction of doing it myself.

I actually have a VATS bypass, but it's the wrong code. I'll probably "revise" it and stick it in. A little more secure than my current fix.

 

My vats acted up on me once. I waited and it started.