bczee

Ok.. was driving around making drop off and on one of them. I turned the engine off, got out and came back in about 5-8 min.. and low and hold.. NO START !.. all of the electrical, digital guages, full pump, lights, everything works, but no starter engaging when the key is turned to start !

It being hot, I couldn't do to much, but did shake and check a few wire and connections, disconnected the battery for a min, shook the shifter in both P and N.. everything i could do without tools and a jack... but no start up..not even a crank..

While waiting for the Tow. .I tried it a few times.. but after waiting about 20 min.. it started.. I drove home and didn't check anything yet.. I switch cars and went back to work (where I am now).

Once I get home, I will check the normal stuff.. wire from Ign to start, solenoid, N-switch..etc. I don't think it is the VATs, cuase it will not even engage the solenoid for the starter to crank.. unless the VAT would prevent the starter from engaging..but unlikely..

But wanted to ask if anyone else has had this problem. And what did they find that was the cauase or one off problems..?

Thanks.. just trying to get a head start on where to check 1st..

IRAraid

Yea, the VATS will prevent the solenoid from engaging the starter. Put a volt meter on the solenoid small lug and check for voltage when the key is in 'start'. If there's voltage, the solenoid is shot. If no voltage, either the shift switch is open (auto) or the clutch switch is open (stick) or the start relay has failed or the VATS has got you. If it's VATS, I think the 'security' light will flash (don't know for your year).
If it's VATS, there are lots of threads on how to test/bypass it.
Good luck.
PS Mine was the solenoid.

Firevette

I second VATS

Redeasysport

I third VATS the 20 minthing is the giveaway.Clean your key or get a new one the resistor wears down over time and may not make contact. If that does not work your in for some fun.

pcolt94

To reset the VATS system, you have to remove the key from the ignition for it to reset. Disconnecting the battery will not reset the VATS timer. It will still take the 3 minutes.

I can’t tell you if the VATS actually activated, but this is how it works and to reset it. You might try cleaning the 2 contacts on the key with alcohol for starters just in case you had a bad contact.

Make sure both battery connections are in good shape is a given.

Never forget about the ignition switch or starter solenoid.

bczee

Thanks Guys.. don't have time to check it.. so the Vette will sit till next week..

my 84' Z28 is apart right now, been changing the oil pan and gasket, clutch and have the T5 apart right now. (Too many projects !).... as I was out pickup parts for it when this happened.

I'll just drive the Nova daily and the Chevelle to the hang outs till I get time to look into this.. but I may have time to get some resistors to bypass the VATS.. I know what # it is.. to I can build a VATS bypass.

I'll update next week sometime.. thanks again..

86PACER

Check the Starter Enable relay and the VATS decoder module. Either of these two will cause an intermittent no crank condition. I've had both fail on me, and both gave identical symptoms. The diagnosis is pretty easy. The only catch is you have to test while it's not cranking, otherwise everything will check out fine and you won't find anything. Left unfixed, you car will eventually just not turn on anymore.

Both of these are located behind the dash trim, so I drove around with no dash trim, my shop manual opened to diagram page, and a volt meter ready to go.

Take your dash trim out and drive the car like that. Then when it does not want to start, use a multi meter to see if battery voltage is getting to the Starter Enable Relay at both the two thick yellow wires on the Starter Enable Relay connector while you hold the ignition switch at the "cranking" position. If there is no voltage, then the problem is upstream at the key or switch. If there is voltage there, then you know the problem has nothing to do with the key or ignition switch and the problem is downstream, either the VATS Decoder Module , Starter Enable Relay, or finally the Starter Solenoid itself. In this case, a resistor bypass will do you nothing. I use the metal seat tracks as a ground to test this.

Back probe, ground the green wire off the VATS Decoder Module and try to start the car. If it now starts, your VATS Decoder Module is bad.

You can either just leave the green wire jumpered to ground and be done with it, or replace the VATS Decoder. The problem with wanting to replace it is that it's discontinued by GM and you have to buy it used at about $100.

Further more, These modules are matched to your key's resistance (1 -15). This means that there is only a 1 in 15 chance that the used VATS Decoder Module you buy will match your car's resistance pellet value and allow you to use your current ignition key, unless the vendor knows what the value of it was and labeled it which is unlikely. Chances are the used parts vendor will not know what the resistance value of the module they are selling you is simply because they get cars with no keys to them, in pieces, etc so it's a total clusterf**k.
So to avoid all this BS, I just grounded mine with a piece of wire to that metal bolt next to it's harness on the dash. It's a good, convenient ground only a few inches away.



Then you have to hire a locksmith use a device to determine your new module's value and make you a new key which drives the price up. Total PITA. The used module will run you about $100 not including the cost of a locksmith for new keys.

If car still won't start with Green wire (top most on harness) on VATS Decoder Module grounded, remove the Starter Enable Relay and jump the outer two terminals with a wire and repeat (see pic below). If it now starts, replace your Starter Enable Relay.

$20 at the dealer. Delco part#14093107 I got an extra one if you need it.

If it still won't start, check the clutch safety switch if your got a manual trans. If auto, try with shift lever in Neutral.

Starter enable relay:


VATS decoder module:


Bypassing Starter Enable Relay:


Testing for battery voltage with switch in "crank" position at each of the two thick yellow wires. Each should have battery voltage.

bczee

I had just finish reading this information in one of the original threads that was posted.. this is a good write up and I will use it to diag my problem once I get some time to follow it.. right now.. the vette is sitting in line to get fixed behind the Camaro (oil pan, clutch and trans), the Van (intake gasket, still running so this can go to the back of the line). Good thing the Nova and the Chevelle is still running good...

bczee

86Pacer.. ok.. I have voltage to both the Yellow wire on the Starter Enable Relay.. bypassed it and the engine cranked, but only ran for a few seconds. so I think we are on to the VATS..

I check the puck on the key.. it was right on.. used some resistors to get close to the correct resestance, jumped the connector for the VATS (bypass).. but it may no difference.. still only ran for a few seconds..

I will replace the relay once I can get one, but being sat.. no one has it in stock and the chevy dealer parts is closed today.

I will try and ground the VATS Module when I get a chance. should the connector be still on the Module and just jump/group the green wire...? or disconnect the connector and then ground the green wire ?

Am I on the right track so far...?

thanks for you help..

Redeasysport

If the Vats is the problem it won't start at all.You might be on a wild goose chase. If the engine starts then dies it is something else all togther.You can try the Vats bypass since you have the resistor value.

bczee

Ok..
Was able to ground the green wire, jump the relay and still only start/run for a second or two.. sure sounds like a VAT proboem.

But looking for direction on this guys.. any other suggestion on what to check or look for.. maybe Ign module?

Fuel presure is good.

86PACER

If you got it to crank over and start than you bypassed VATS successfully. Sounds like you have two problems. Now you have to see why it won't stay running which I don't feel VATS is causing.

Redeasysport

Time to break out the FSM. Fuel ,air and spark. Check your fuel pressure first. Before during and after start up. Then move onto spark.

bczee

Well I still don't have a FSM.. Here is what I have found out so far..

Grounding the Green wire at the VATS Module will allow the car to crank and start up, but for only a second or two. Removed the ground and no Crank. so..I take it that the Relay is good. Fuel pressure checks out ok.. So. do you think I have a bad VATS Module ?

Redeasysport

No the VATS is no longer your issue. It does not make the car die after start up. Do a VATS bypass as suggested above until you can get it to run. Then go back and revisit the vats issue it may be bad or your key is worn out or the contacts in the ignition none of which are issues if it is bypassed. You really need to get a FSM you are flying blind.

When you say fuel is OK what does that mean you need to be very specific so we do not miss a thing. What did it read on the gauge when the key was turned on. What did it read when the engine started? What did it read after it died and how long did it hold pressure. That is the description of a fuel pressure check.

86PACER

You have proven that your VATS decoder module is bad by only getting the starter to spin with Green wire manually grounded. If your Starter Enable Relay was plugged in during this and not bypassed, you have also proven the relay to be good. Mine is exactly the same. I left mine grounded and called it good to avoid having to chase a new VATS decoder module down for the reason I already mentioned above. Indeed it appears that you had more than one problem. You have already adressed the VATS problem which was not letting your car crank. The VATS decoder simply determines if the key in the ignition is the right resistance. Now you need to find the problem that is letting the engine die.

I'd try to pull some codes in search of the other problem. If there are stored codes, that gives you a starting point. Check for codes and report back. All you need is a paper clip and this link:






http://corvettebuyers.com/c4vettes/ecm.htm

Redeasysport

I am going to take a WAG at your problem based on another thread. If you find the FP drops after start up on the guage( I bet you do) it starves out and dies. This indicates a disconnected/ bad Oil Pressure switch. When you turn the key on the FP relay charges the rail for 2sec. and after start up the Oill Pressure switch should keep the pump running. I bet it isn't doing that.Check it out.

Your Vats is another issue and instead of throwing possibly unnecessary parts at it you need to get you hands on a FSM and do the diagnostic on it. I am not convinced it is the module there are other things in the loop as I mentioned already and those need to be eliminated before laying out $100 for a module. You now know how to bypass it. I have no doubt the module is not letting it crank but do not shoot the messenger yet. It is telling you it does not recognize the key.

pcolt94

The bendix gear is not engaging with the flywheel. The solenoid could be bad or bendix sticky. You are just probably better off replacing the whole starter and be done with it.

86PACER

Pulled any codes yet?

bczee

The Vette has been sitting.. but the Z28 is now running ! ...

Went over to my buddy place and picked up a MAC tool Scanner.. It has the correct software to pull codes and monitor the data streams.

But before I get to the Vette.. have to work on the Chevelle.. behind on it, and there is a show this sunday. Cutting the front springs (1/2 a coil) to bring it down a bit.. but no time this Sat.. golf Tournament!...

Then it will be back to the Vette.. Will let you know next week (I hope !). I have a feeling that my VATS bypass is not setup correctly... I will redo that to ensure that the VATS/Key is out of the picture.