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If I was driving down the road, with my VATS bypassed with a resistor, and then were to disconnect the resistor, would the VATS no longer read the resistor and then stop sending the signal to the ECM which would then turn off the fuel? As in turn off my car while I'm driving it. Or does it only care that the resistor is in there when trying to start the car?
Thanks.
IIRC, VATS matters only during cranking and once the car is running, the ECM doesn't use the signal anymore.
But that should be easy to test/prove. Start the car and unplug the small white connector under the dash. If the engine dies, I'm wrong.
vats should not matter once the car has been started.even with vats messed up, you can turn the key to on position, jump the starter and the car will crank. i did this to get home and intall the correct diode the next day.
Just for some info....my '91 305 car used to have a problem while driving down the road......it didn't happen often, but on occasion I'd be cruisin' along just fine, and then all of a sudden the car would kill all power, acting like it ran out of gas or shut of ignition system...anyways when it did this the 'security' light would come on, and i'd have to pull over and wait 15 minutes or so before I could start the car again. Well after a while Of this happening I got sick of it, took it in and it turned out to be the VATS system...I had it replaced along with the chip in the keys....after that it never did it again....hope that helps somewhat...
I agree, once the car is started the VATS does not come into play. This past year I was driving back from Fl to GA with the car running fine. Turned it off for 5min to get fuel, drinks and hit the rest room. I tried to start the car and it would not run.
The car sounded like it wanted to run, but would not catch. After two hours of trouble shooting I had the car towed to the local GM dealer in DeFuniack Springs Fl. After 10 mins they determined it was the VATs. They fixed the problem, which required a new key and all was well.
It took the dealer about 90 mins and cost me about $300. They said, one of the wires (a VAT wire I assume) had worn through from years of use from the tilt wheel being moved up and down.
Long and short of it is the car ran fine, but once it was shut off it would not start again.
So I'm getting 3 "no it don't matta", and 2 "yeah boi it does". In the shop manual, it says the VATS module is turned on when the key is turned to run, bulb test, or start. It also says, "When the VATS module senses the proper resistance at the ignition key, it will output a square wave signal to the ECM." I take that to mean it constantly outputs the signal. I would do this in real life and be done with it, but like I said, I got no car. I would really appreciate it if someone could test it for me.
As a update to a year's old thread. I was just driving down the block security light comes on car lost all power for 2 seconds ie interior lights, exterior lights engine stops running . I assume it's a bad vats connection because after 2 sec the car got all power back and continued to run without restart. Will check wiring Tommorow but this would prove it needs vats all the time or will shut down entire car!!!
Both engine shut off all interior and exterior lights. Happen for about 2 seconds then everything came back on and engine continued to run. About 2 minutes later same thing happened. Makes me assume it's the resistor connection which I have under the kick panel
Vats is like an initial handshake, to start the engine the passkey expects to see proper resistance of the key. Once recognized it sends a hz signal to the computer to enable injectors. This only happens during initial start.
also to be clear iwas saying if I found a bad vats resistor connection, that would prove it shuts engine and electrical while driving.
No it would not, because it can't. Go look at a wiring diagram for your vehicle, you will see that VATS is connected to the ECM and the start enable relay.
Total denial of electricity is going to be something like a tripped breaker, loose battery connection, or compromised fusable link. Something early in the power distribution circuit.
No it would not, because it can't. Go look at a wiring diagram for your vehicle, you will see that VATS is connected to the ECM and the start enable relay.
Total denial of electricity is going to be something like a tripped breaker, loose battery connection, or compromised fusable link. Something early in the power distribution circuit.
Thank You to both Komet and Tuned for setting this thread straight.
George, these gents are right, you have a different wiring fault that doesn't originate with VATS. VATS kills exactly two things and two things only, at startup only; the fuel injector pulse, and the starter's ability to crank the engine. VATS will NOT kill a running engine. The fact that the security light comes on during your intermittent power failures is a symptom of the failure of your car's power distribution, and is not the cause.
Vats is like an initial handshake, to start the engine the passkey expects to see proper resistance of the key. Once recognized it sends a hz signal to the computer to enable injectors. This only happens during initial start.
I am looking at the pass key diagram where does ecm/ign show that its only limited to start up? Not disagreeing with you, just learning the wiring!
You can't tell by wiring alone, you'd have to read the operational description in the GM service manual. People that seem to have some kind of deep knowledge really just have service manuals that they know how to use and reference.
Various modes for the system. This case would trigger this:Fail Enable: This mode is to help keep the motorist with the right key from being stranded. If a
failure happens to the PassKey system AFTER a valid start, this mode is initiated. It allows the
vehicle to be restarted, even with a failure present. The security light will remain illuminated to let
Thank You to both Komet and Tuned for setting this thread straight.
George, these gents are right, you have a different wiring fault that doesn't originate with VATS. VATS kills exactly two things and two things only, at startup only; the fuel injector pulse, and the starter's ability to crank the engine. VATS will NOT kill a running engine. The fact that the security light comes on during your intermittent power failures is a symptom of the failure of your car's power distribution, and is not the cause.
While I try and rap my head around what exactly happened. I realize my stupidity in thinking it Could be the security system. Considering I lost all power to even the fog lights. Obviously the VATs not going to turn off headlights
Now the reason I say only the fog lights (And this may be a Hint here To helping diagnose the problem) When I went to leave the House The headlights would not flip up Nor turn on. So considering I was only going around The block I went with just my fog lights.
It is as if I turned the Ignition off and on. But once again with the Ignition off my headlights should work. I saw someone else post the same thing and their headlights had problems also. Any ideas what would be In common between losing all power and a headlight issue, which Obviously should turn on regardless of position of Ignition?
As for fusible links how many are there and do you know their location? Is there a main ground that would cause this?
The MOST common problem found for something like you have tried to describe is...
Loose or Broken Main Ground Connection from the Battery to the Engine/ Cylinder-Block.
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.
.
.
As the other Members have already stated...
Start by inspecting all Main Power Connections from the Battery.
.
.
.
.
Also... Our Cars are seriously lacking in regard to the Battery/ Power Cables.
Now is the right time to Update/ Upgrade to proper/ modern Main Power Connections:
-Positive Cable from Battery to Starter Motor Solenoid.
-Positive Cable from Battery to Alternator.
-Negative Cable from Battery to Engine/ Cylinder-Block.
-Negative Cable from Battery to Uni-Body/ Frame.
-Negative Cable from Battery to Body of Alternator (NOT near the Charge Stud/ Bolt).
.
The MOST common problem found for something like you have tried to describe is...
Loose or Broken Main Ground Connection from the Battery to the Engine/ Cylinder-Block.
.
.
.
.
As the other Members have already stated...
Start by inspecting all Main Power Connections from the Battery.
.
.
.
.
Also... Our Cars are seriously lacking in regard to the Battery/ Power Cables.
Now is the right time to Update/ Upgrade to proper/ modern Main Power Connections:
-Positive Cable from Battery to Starter Motor Solenoid.
-Positive Cable from Battery to Alternator.
-Negative Cable from Battery to Engine/ Cylinder-Block.
-Negative Cable from Battery to Uni-Body/ Frame.
-Negative Cable from Battery to Body of Alternator (NOT near the Charge Stud/ Bolt).
.
I am going to take a look Tommorow to see what I find. I will definitely upgrade cables.
The MOST common problem found for something like you have tried to describe is...
Loose or Broken Main Ground Connection from the Battery to the Engine/ Cylinder-Block.
.
.
.
.
As the other Members have already stated...
Start by inspecting all Main Power Connections from the Battery.
.
.
.
.
Also... Our Cars are seriously lacking in regard to the Battery/ Power Cables.
Now is the right time to Update/ Upgrade to proper/ modern Main Power Connections:
-Positive Cable from Battery to Starter Motor Solenoid.
-Positive Cable from Battery to Alternator.
-Negative Cable from Battery to Engine/ Cylinder-Block.
-Negative Cable from Battery to Uni-Body/ Frame.
-Negative Cable from Battery to Body of Alternator (NOT near the Charge Stud/ Bolt).
.
when u state ground from Alternator to Battery (not near stud)
where does it connect to if not on stud? Thanks
when u state ground from Alternator to Battery (not near stud)
where does it connect to if not on stud? Thanks
Attach the Ground Cable to one of the Bracket Bolts for the Alternator...
Or to any Bolt on the Case of the Alternator...
Or to anything touching the Alternator with a Bolt.
Stay away from the Charging Stud, or you will have a MASSIVE Short!
Attach the Ground Cable to one of the Bracket Bolts for the Alternator...
Or to any Bolt on the Case of the Alternator...
Or to anything touching the Alternator with a Bolt.
Stay away from the Charging Stud, or you will have a MASSIVE Short!
On a lot of the GM vehicles there is a grounding point at the rear of the passenger side head. This gets a lot of movement and vibration and sure can come loose and corroded, cause a bunch of problems like you're describing. Hard to see and to get to but worth a look back there.
On a lot of the GM vehicles there is a grounding point at the rear of the passenger side head. This gets a lot of movement and vibration and sure can come loose and corroded, cause a bunch of problems like you're describing. Hard to see and to get to but worth a look back there.
yes I took a look at neg batt to motor and behind both heads they are both connected . Now time to get under the car. Just need another cup of coffee!.
on the driver's side back of head there is a prong that sticks up, if I remember correctly something was connected there. Nothing attached now!. Anyone know what goes there?
yes I took a look at neg batt to motor and behind both heads they are both connected . Now time to get under the car. Just need another cup of coffee!.
on the driver's side back of head there is a prong that sticks up, if I remember correctly something was connected there. Nothing attached now!. Anyone know what goes there?
I have rewired all grounds in the car the passenger side had one was loose we will see if that helps fix... Does anyone know if anything goes to the prong that sticks off Driver's side head ground?
george88gta, I gotta take a moment to applaud you for taking advice and then just gettin' to it to try to solve the problem. The gettin' to it part is kinda rare. Makes it much more satisfying to take time to help people like you.
Btw Id be looking at fusiable link wire conditions
i fully agree with Tuned Performance advice to you and would really check these... the main ones are on the starter stud and going from memory there is one of them i believe that is a double connection on a terminal that feeds several different circuits including ignition. i don't have the service manual in front of me at the moment, but i believe this is a key area to confirm
george88gta, I gotta take a moment to applaud you for taking advice and then just gettin' to it to try to solve the problem. The gettin' to it part is kinda rare. Makes it much more satisfying to take time to help people like you.
Thanks I just pulled the car out of my grandmother's garage A few months ago for the 1st time in years. I'm on a mission to get everything done correctly.
That will let him see where are the fusible links in wiring schematics for main power distribution. It will also show him all ground locations.
Maybe I should be embarrassed I have the manual, I try to keep a lot of questions On here as I know They help me and others. If I can't find the answer here i go through the manual.
As for grounding the alternator On the back terminal one wire goes to the battery the other 1 goes to a while loom below the battery, I just realized that connection is somewhat hot when I touch it , I would imagine it's safe to assume it needs to be grounded after reading your post is there no other ground to the alt from the factory?
Our Cars ONLY have the Positive Cable for the Alternator to the Battery.
There is NO Negative (Ground) Cable from the Factory.
You are going to Add a new Negative Cable. STAY AWAY FROM THE POSITIVE POST/ CABLE ON THE ALTERNATOR!
The Negative Cable just touches the Body of the Alternator or the Bracket.
.
.
.
Our Cars ONLY have the Positive Cable for the Alternator to the Battery.
There is NO Negative (Ground) Cable from the Factory.
You are going to Add a new Negative Cable. STAY AWAY FROM THE POSITIVE POST/ CABLE ON THE ALTERNATOR!
The Negative Cable just touches the Body of the Alternator or the Bracket.
.
.
.
ok I added a ground strap. I guess gm thought the one to engine was sufficient. Odd considering it has no good connection to that ground.
Maybe I should be embarrassed I have the manual, I try to keep a lot of questions On here as I know They help me and others. If I can't find the answer here i go through the manual.
I get it. I had the manual for years before I really looked through it. It's fantastic! The information in it is amazing. Cannot encourage people enough to thumb through those manuals and see what's in there.
For the electronic copy linked below, I made an index in a spreadsheet for what topics are at which page numbers. It's kind of hard to find anything quickly without an index like that.
I get it. I had the manual for years before I really looked through it. It's fantastic! The information in it is amazing. Cannot encourage people enough to thumb through those manuals and see what's in there.
I agree, I have read some interesting info. I am going to dive into it again in the morning to double check my work
Was going through this thread because my car died on Sunday.
Sunday afternoon, I tried to start the car, got nothing. No crank, no power whatsoever, all lights dead. I had driven the car earlier in the day.
Sunday night, I went to the garage and just opened the car door. Interior lights came back on.
Monday, the thought of a bad VATS key popped into my head. Tried a different ignition key and the car started. Drove about 10 miles.
Later on Monday, I tried to start the car again. It cranked up. Just curious, I tried the original key again. The car once again had no power whatsoever. No crank, no lights, no electricity to anything.
Today, it's still sitting there, stone cold dead. No electric at all.
Despite the one key seeming to cause this (and even if it did, the VATS should have only locked the car temporarily, not for 15 hours now), it sounds like there is something else wrong with my electrical system having nothing to do with VATS. Any ideas where I should start?
Was going through this thread because my car died on Sunday.
Sunday afternoon, I tried to start the car, got nothing. No crank, no power whatsoever, all lights dead. I had driven the car earlier in the day.
Sunday night, I went to the garage and just opened the car door. Interior lights came back on.
Monday, the thought of a bad VATS key popped into my head. Tried a different ignition key and the car started. Drove about 10 miles.
Later on Monday, I tried to start the car again. It cranked up. Just curious, I tried the original key again. The car once again had no power whatsoever. No crank, no lights, no electricity to anything.
Today, it's still sitting there, stone cold dead. No electric at all.
Despite the one key seeming to cause this (and even if it did, the VATS should have only locked the car temporarily, not for 15 hours now), it sounds like there is something else wrong with my electrical system having nothing to do with VATS. Any ideas where I should start?
look at the fusible link connections at the starter... if you have no power at all it likely could be one of these. i had a ring terminal on one of these that had broke and would make intermittent connection ... everything great then everything dead
04-15-2009, 10:11 PM
I get it. I had the manual for years before I really looked through it. It's fantastic! The information in it is amazing. Cannot encourage people enough to thumb through those manuals and see what's in there.