VATS Question

[KFoster]

At least I think it’s a VATS question. I bought a bypass for the ignition a while back and installed it. My problem persists though. Car will crank fine. Then when I shut it off, it may or may not crank back up. Doesn’t trip the starter solenoid or anything. Security light will come on then go off without it cranking or trying to crank. Then leave it for a while and it will crank just fine. So, I still can’t trust this thing. Would like to park it at Walmart with the keys in it. Any ideas? I would like to totally and permanently disarm the VATS. If someone steals it, fine. I can’t use it as it is.


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[GOLDCYLON]

At least I think it’s a VATS question. I bought a bypass for the ignition a while back and installed it. My problem persists though. Car will crank fine. Then when I shut it off, it may or may not crank back up. Doesn’t trip the starter solenoid or anything. Security light will come on then go off without it cranking or trying to crank. Then leave it for a while and it will crank just fine. So, I still can’t trust this thing. Would like to park it at Walmart with the keys in it. Any ideas? I would like to totally and permanently disarm the VATS. If someone steals it, fine. I can’t use it as it is.


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I wonder if this is the infamous clutch safety switch which is mimicking a VATS issue. A lot of us have had this bypass done due to the "Starts run fine, shutoff then wont start for hours"


Look up clutch bypass in the search there is a lot data on this. GC

[KFoster]

I appreciate the response. I guess it’s hard for me to think it’s that even though I have read so much about it on here. Rather not bypass it is one issue. I would think it would either work or not, why would the switch not go out entirely? My fist corvette. Owned several and worked on a bunch of mustangs and I’ve never seen a clutch switch problem. Probably a dozen or so Camaros with no issues, but that’s more limited. Guess it just makes me think it’s not that. If it wouldn’t crank at all I would think clutch switch.


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[mhobtr]

Would like to park it at Walmart with the keys in it. Any ideas? I would like to totally and permanently disarm the VATS. If someone steals it, fine. I can’t use it as it is.


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I'm right down I-65 from you in North Shelby County. If you are going to throw it out, let me know and I will come haul it off for you.


Seriously though, I installed the bypass relay on mine and the starter isues are no more. Have you checked the terminals at the starter to be sure they are clean?

[KFoster]

Yes. Starter was good when I painted the intake. I’ll look into the bypass. Would rather disable VATS first if that is possible.


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[Dynomite]

Seems to me it be a sticky solenoid related to heat as you stated "doesn't trip the starter solenoid" when turning the key on a hot engine.

The only item in that starter circuit that gets hot is the starter itself including the starter solenoid. And this issue is definitely related to Heat.

It could also be the coil that creates the magnetic force to pull the Solenoid closed. You should be able to hear a click when you turn the key if the Solenoid moved into contact position. If you do hear a "click" then it be the Starter Solenoid Points which is a normal restoration item when I do a "Top End Restoration". I always check the freedom of movement of the Starter Solenoid also and clean the Solenoid and cylinder in which it moves :cheers:

I would not "disable" Vats or disable anything as a fix. (That is not a restoration...…... kind of like solving the Power Key lack of function by eliminating the Secondaries) :p

I DO eliminate the TB Coolant function as that really has no usable function as I do NOT drive the Zs in cold (icy) climates when it is 15 deg F or colder.
Post 192 - Injector Housing TB Coolant Blocking (https://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-10.html#post1588695506)

I DO install the Starter Relay on all Zs (except 95') to cure the possible low voltage (do to Starter Circuit deterioration or low battery voltage over time) to the starter Solenoid.
Post 52 - Starter, Starter Relay, Wiring Harness, Battery, and Plugs Tricks (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-3.html#post1581564085)

You can HOT WIRE the Starter Solenoid to see if that is an issue going direct (purple wire) from battery to Starter Solenoid (Key off and in neutral).

Remember the Zs are very easy to push start in second gear in emergencies :p

[mhobtr]

In the first post you said " I bought a bypass for the ignition a while back and installed it."

What did you buy?

[KFoster]

VATS code 12 security override system. $31. You check the ohm of your chip in your key and then order the bypass harness with the correct resistance. It installs easily. It thinks the chip in the key is always making contact.


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[mhobtr]

Sooner or later all Z owners have to deal with the low voltage issue in the starter circuit.

Installation of the bypass relay will eliminate that.

I wrote a long dissertation as to why but then figured it was too boring and no one would be interested, so I deleted it.

[Dynomite]

Sooner or later all Z owners have to deal with the low voltage issue in the starter circuit.

Installation of the bypass relay will eliminate that.

I wrote a long dissertation as to why but then figured it was too boring and no one would be interested, so I deleted it.


I would be interested in any technical discussion/dissertation you may have.....I always learn something :handshak:

I have deleted many technical posts when I see no comment/response or lack of interest but I give it a chance :D
There are many that look and learn but do not say anything :p

[32valvesftw]

I would be interested in any technical discussion/dissertation you may have.....I always learn something :handshak:

I have deleted many technical posts when I see no comment/response or lack of interest but I give it a chance :D
There are many that look and learn but do not say anything :p

Very true sir.

[mhobtr]

I must say that if Mr. Dynomite is the least bit interested in my opinion I must reply. But don't say I didn't warn you.

There are two electrical circuits in the starter system. The start solenoid circuit, which energizes the solenoid, and the starter circuit, which actually powers the starter.

The starter is a high ampere power draw and must be connected directly to the battery in order to deliver the necessary torque to spin the motor. In the original electric start automobiles, there was a pedal on the floorboard which was pressed to engage the starter gear with the flywheel and simultaneously connect power to the starter motor.

The inrush current of the starter motor is hard on any switching device because the arc generated burns the switch contact each time the circuit is engaged. The electric solenoid was developed to allow a simple push button operation to engage the starter. The solenoid utilized (and still does) a copper disc and a copper stud which, when pressed together energizes the starter motor. Each time they make contact, the disc and the end of the stud will be burned but the disc will rotate to a clean spot for the next start event. This works fine until the disc is covered in burns and the stud is heavily carbonized resulting in a switch connection that is of such a high resistance that the motor does not receive enough voltage to to deliver the necessary starting torque.

On the early Chevys (mine was a '56), the solenoid was easily disassembled to allow the copper disc to be turned over, and the stud turned around, which resulted in an "as new" solenoid.

The solenoid on GM cars also engaged the starter gear to the flywheel. Fords and many European cars utilized the centrifugal force of the stater motor to "spin the gear" into the flywheel.

The early starter circuits were simple and typically connected directly to the battery output so the solenoid got full voltage when the switch was engaged. The early autos had only a push button in the solenoid start circuit, which was later replaced by the key switch. Kirchhoff's law states that the sum of voltages across each resistance in an electrical loop will equal the voltage applied. So in the solenoid circuit there is a voltage drop across each device in the circuit and each one added will result in lower voltage delivered to the solenoid. The clutch switch, the key switch, the alarm system switch, and ?? (i can't remember what else) are each a resistance in this circuit and each will act to lower the voltage delivered to the solenoid. As these devices age, especially the clutch and key switches, their resistances increase and further lower the solenoid voltage. This is the fundamental cause of the dreaded "no start" in the ZR1 system. (I believe someone posted that they measured less than 11 volts at the solenoid).

The force delivered by the solenoid to engage the disc to the stud is directly proportional to the voltage applied from the start circuit. I can't prove this but I'm pretty sure that weak force to the disc will result in chattering of the contact which further exacerbates the demise of the disc and stud.

The bypass relay circuit developed to eliminate the "no start" problem connects battery voltage directly to the solenoid, via the new relay, and replaces the high resistance of the solenoid with a low resistance relay coil in the starter key circuit. The lower overall resistance in the start circuit results in lower current flow and adequate voltage at the relay.

This is as the circuit should have been designed originally but they can't think of everything.

[JFFerner]

Another one read it, thanks. Jim

[Dynomite]

I must say that if Mr. Dynomite, is the least bit interested in my opinion, I must reply. But don't say I didn't warn you.



In -Solutions- (third page under Starter) :handshak:

Thank you for that explanation :thumbsup:

And.....Thank you for explaining and suggesting earlier the Function of the Bypass Relay which bypasses the age deterioration in the Starter Electrical Circuit giving many more cycles of great starting...….

Merry Christmas to ya :cheers:

[DRM500RUBYZR-1]

Another one read it, thanks. Jim

I am with him!

Will also point out, that if the battery cannot deliver 13.6 volts during a start sequence on a C-4,5,6, it often results in a no-crank condition.
Lights and all else look good, which often leads you down the wrong path.
to borrow and re-word a real estate maxim of Location, Location, Location.
BATTERY, BATTERY, BATTERY.
:cheers:
Marty

[KFoster]

Once again I appreciate the help. My problem has been with a hot battery. It will eventually crank if you leave it long enough. That is what made me think VATS. I think I will try the clutch switch bypass. If it happens after that I will go another route. If it doesn’t, then that was it. Afraid to drive it and try it. Seems to be fine as long as I come back home. It likes leaving me stranded away from home.


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[Dynomite]

I think I will try the clutch switch bypass. If it happens after that I will go another route.

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My 02 cents...…..I am thinking that bypassing the clutch switch means it will start without depressing the clutch :rolleyes:

I would install the Starter Relay which basically removes the Clutch Switch from the Starter Solenoid Circuit without disabling the Clutch Switch (The Starter Solenoid Circuit is then from Battery to Relay To Starter Solenoid). The installation of the Starter Relay is all top side just under the ECM. The Clutch Switch still functions as a safety from starting the Z in gear.

The easiest way to test that circuit is......next time you get the Z home (hot), find the purple wire in wire bundle under ECM and with car in neutral, connect a wire from positive battery post to that purple wire with alligator clips (just scratch a bit of insulation from purple wire) and the engine should turn over with SHIFTER IN NEUTRAL and KEY OFF.

If the engine turns over that will mean you have a bit low battery (You obviously have enough battery to start it cold) or you have a bit too much resistance in starter circuit which the Relay will eliminate simply because closing the contacts of the Relay takes considerably less voltage than moving the Solenoid in the Starter. This will also provide FULL Battery Voltage to a sticky Starter Solenoid.

mhobtr can explain this much better than myself and mhobtr is welcome to correct me if I misstated :handshak:

Sooner or later all Z owners have to deal with the low voltage issue in the starter circuit. Installation of the bypass relay will eliminate that.

I installed the bypass relay on mine and the starter isues are no more.

tccrab (TomC) was the first as far as I know to solve this no start issue :thumbsup:
No start cure by tccrab (http://www.zr1.net/forum/showthread.php?p=98493)

I modified the Circuit a bit to assure pin 87a is never hot.
Post 52 - Starter, Starter Relay, Wiring Harness, Battery, and Plugs Tricks (http://forums.corvetteforum.com/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-3.html#post1581564085)

One additional Restoration I do in ALL Zs (in addition to installing the Starter Relay) is reconditioning of the Starter Solenoid especially if you get a click indicating the Solenoid is moving but the contacts are burnt.