OK, I PUT A 350 IN MY 91 Z-28 AND I HAVE NEVER GOT IT TO CRANK. WHEN I TURN THE KEY ON THE SECURITY LIGHTS COMES ON AND STAYS ON. SO I CHECKED FOR POWER ALL THE WAY TO THE START ENABLE RELAY AND I HAVE POWER AT THE RELAY WHEN I TURN THE KEY. BUT THERE IS NO POWER COMING FROM THE RELAY (VIA THE TAN/WHITE WIRE) SO I BOUGHT A NEW RELAY. WELL I PLUGGED IT IN AND NOTHING...THE SECURITY LIGHT STILL COMES ON AND STAYS ON AND IT WILL NOT ENGUAGE THE STARTER SO NO CRANK. WHAT AM I MISSING? IS THERE SOMETHING I'M FORGETTING?
AND THE CAR DID START BEFORE THE CRACKED BLOCK THAT LED TO THE 350 SWAP.

 

Tan/white wire is your fuel pump. Can you hear that prime when you turn the key to run.

Starter enable relay will have big purple, yellow and brown wires going to it along with a small yellow/black wire. If you connect this yellow black stripe wire to a ground, there car should crank when you twist the key. Should only run for a few seconds without VATS operational.

Is the VATS key cylinder wire connected? Two thin wires going to their own small connector out of the steering column.

 

YES THE VATS WIRES ARE CONNECTED, BUT MY START ENABLE RELAY HAS TAN/WHITE WIRE BLACK/YELLOW AND 2 YELLOW WIRES. THE CLUTCH SAFETY SWITCH HAS THE PURPLE WIRE AND TAN/WHITE WIRE
OH ALSO YES THE FUEL PUMP PRIMES WHEN I TURN THE KEY ON

 

OK. I CHECKED OHMS ON MY KEY. THEN PUT THE KEY IN THE IGNITION AND MEASURED THE OHMS AT THE CONNECTOR WITH THE 2 WHITE WIRES WRAPED IN ORANGE AND I GOT THE SAME VALUE AS THE KEY. AND I HAVE VOLTAGE AT BOTH YELLOW WIRES ON THE START ENABLE RELAY WHEN I TURN THE KEY. SO I PLUGGED IN THE RELAY AND I HAVE POWER AT THE BLACK WIRE WYELLOW STRIPE WHEN I TURN THE KEY. THERE IS NO VOLTAGE AT THE TAN/WHITE WIRE. SO I DISCONNECTED THE CLUTCH START SWITCH AND DID THE OLE PAPER CLIP TRICK AND JUMPED THE PURPLE WIRE TO THE TAN/WHITE WIRE. AND I AM NOT GETTING VOLTAGE TO THE CLUTCH START SWITCH AT ALL KEY ON KEY OFF KEY TURNED IT DONT MATTER NO VOLTAGE. ANYONE KNOW WHY I WOULD NOT BE GETTING VOLTAGE TO THE CLUTCH START SWITCH?

 

ok i just noticed something weird..... the value of my key is 1711 and i looked at the chart and it is not matching any values on the chart. the value that is the closer of the 15 is a lot higher than my key. has anyone had a problem like this before? or know what to do about it?

 

Still is tracking back to your VATS module. I've not heard of a key changing resistance. There is a big range for each the 15 values. Your VATS module should be supplying a ground to your enable relay. It doesn't appear to be if you are reading a positive voltage through the relay coil from the yellow wire.

If you jump the relay by shorting (paper clip) one of the yellow wires directly to the tan/white wire you will see what I mean. The car should crank with key twisted and peddal pushed in. Your peddle switch is dead because the relay isn't sending power to it. The purple wire is connected to the starter.

If you ground the small black yellow wire like the VATS is supposed to do, it will crank as well. I'd want to unhook it from the VATS module to be safe though.

Doesn't solve your problem with the VATS, only isolates it. New module and matching keys or a $20 bypass from e-bay are the easy/quick answers.

 

ok first of all thanks for taking the time to help. I took my test light and closed the relay manualy with the pointy end and had a paper clip jumping the clutch switch so i didnt have to push the peddle and the car would turn over but would never crank. Does that point to anything other than the vats module being bad? or should i say to H with it and go ahead and by the bypass thingy? and agian you have my gratitude for your help.

 

When you say "turn over but would never crank" I'm assuming the engine was spinning at normal speed but not firing. I don't understand how you could manualy close the relay with your probe. Did you connect it directly to a ground?

Yes, the security light staying on, failure to activate enable relay and a lack of injector signal to engine all point to a bad VATS.

Checks you can do:
Unplug starter enable relay and probe black/yellow ground wire in connector with ohm meter to ground and see if it is making a circuit.
Put a noid light on one of your injector connectors to see if it is pulsing while the engine is cranking. I think these may be hard to get to on a TPI car.
You can buy all 15 resistors from Radio Shack and try each one in the connector going towards the VATS module to diagnose a bad key chip.

 

my test light was not connected to anything I just used it to push the contacts togeather in the relay and turn the key at the same time. the engine would turn at normal speed but would never crank.

 

I'd put all the connectors back they way they should be. Back probe the ground wire in the enable relay with a piece of wire connected directly to a ground and confirm the starter now works like it is supposed to. Then I'd jump to conclusions and start blaming the key or the VATS module.

 

ok tomorrow i'll do that and I have resistors that match 1870 ohms which is the closest to my key. I'll put them in and do the grounden on the start enable relay and post how it go's. also I found a vats bypass module at baker electronix .com its 25 bucks so if nothing else works I might just go ahead and buy it.

 

Ok, I grounded the starte enable relay and the starter did what its supposed to do. but as I was putting the resisters togeather i found that good ole radie shack sold me a few bad ones. so I got to go back and buy a few more. But i have another question. I was told if I ground the start relay that my car should run for a few seconds and then die and if it does not then there is more wrong than just the vats. Is there any truth to this? if there is then I have more than one problem cause my car just turns over and never fires.

 

I have read many times that the car should run for several seconds as well, but I can't verify this with first hand knowledge. Can you borrow a code reader or scanner to confirm your PCM is alive and well? Even without it running the reader should be able to talk to it. Can you verify its getting spark and that the injectors are running?

 

guess what............it must have been the key because i put togeather some resistors and the value was more than what my key was reading and the security light went out. i tryed to start the car but it never fired and then the battery went dead. so i'm gonna recharge the battery and try agian. i have a set of noid lights and i will check the injectors agian to make sure. and i have a scan tool but its not designed to read both obd 1 and obd2 but a few guys that i work with have one that will read both so i'll borrow it.
i'm all excited and sh*! hopefully soon i'll be able to drive it.

 

OK here we go. Noid light test good all the injectors are getting power like they should. I tested the injectors with my ohm meter and all were at 15 ohms. But I am still not getting any fuel through the injectors. there is fuel at the release valve. any ideas?

 

How are you determining there is no fuel through the injectors? Is this a TBI car? If you give it a shot of starting fluid will it fire? Don't spray it on the MAF if you have one.

I would check the fuel pressure. Maybe its too low to operate injectors. When you turn the key to run, the fuel pump should run for 5 seconds or so to prime the system. Is it really noisey? Does it run much longer? May be a failing pump. Maybe the injectors failed along with your VATS problem. Not likely.

 

I put gas in a spray bottle and would spray it in the intake and it would fire and run as long as i was spraying. and its a TPI not tbi. I checked the fuel pressure today and I'm getting right at 40psi. So I don't understand why it wont run. I have checked fuel pressure, injectors ohms and the connectors with a noid light, it has gas in it, and when i spray gas into the intake it fires. but on its own it will just turn over but never fire.......wait I got it I'll kick the tire, i ain't tried that yet.

 

You mean you haven't tried "emergency rectifying procedure number 1" yet?

The noid light flickers while you are cranking correct? You also have your resistor in place to bypass your bad key. When the resistor is in place, the starter enable relay is getting a ground from the VATS and not a jumper wire correct? I'm not familiar with the ohms test on the injectors. It has good fuel pressure. Its clearly not getting gas through the injectors which is a VATS or PCM problem. The cord isn't long enough on my scanner to reach your car in NC. Wish somebody else would chime in...

 

ha I'm about to kick more than just the tire. But yes the noid lights do flicker. And yes I put the resistors in and the security light goes off and no the start relay is not jumped. the ohm test on injectors is you unplug the injector and measure the ohms on the fuel injector if its 10 ohms or less the injector is bad. if it is 11-16ohms the injector is good. but i thought maybe the ecm was the route of the problem but the noid light flickers so I'm stumped.

 

ok i had a revelation today while i was at work. i got my fuel pressure guage out and i smelled the gas on it......hummmm i said to myself "self....this smells very weak." and I got to thinking. I bet i have bad gas. so tomorrow I'm gonna make my car **** in a cup so I can verify if it has bad gas in its veins. I'll keep ya posted.
oh to kinda tell the story. i live in western nc. you may have seen us on the news about a gas shortage about 2 months ago. there was a lot of bad gas at a lot of the stations for around $4.50 a gallon

 

Sounds like a good idea. Hope the car isn't full (mine would be). The only other idea I came up with was a clogged fuel rail or injectors. I filled my truck up yesterday for $1.55/gal. Quite a swing from $4 in August.

By the way for your other problem, I picked up a $9 key off of ebay (once you know what number to ask for) and Home Depot cut it for free. No issues in my son's '94 caddy with VATS.

 

Could you tell me where to locate the VATS Module? I have a 1991 z28 5.7 and I don't know where it is. I'm new to this and I'm not too sure on how to send or receive messages on here, if you don't mind could you e-mail me with your response. fnx117@yahoo.com, thank you very much.

 

e-mail sent

 

I need to know as well. I took the whole dash apart and cannot locate this thing! I hate VATS!!

 

I also need to know where the VATS Module is.

 

I am having the same problem.
I did a LT1 swap into a 92 RS, it will do nothing when I turn the switch. the ECM for the LT1 has the VATS removed. the 92 VATS is still in the car and the 305 ECM has been removed. I can take a jumper wire and jump the starter relay (large yellow to large green) the car will crank, start and die as soon as I let go the car will die.
some one help us!!