C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

No crank situation

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Old Oct 4, 2023 | 05:06 PM
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Default No crank situation

On my 90 coupe.

Codes 46 and 51.

Last thing I messed with was when I tore the top part of the steering column apart to replace a multi-function switch.

Ignition barrel fell out a few times and dangled by the wores.

I don't know how to move forward with this particular thing because I donlt know anything about the vats system, other than I don't use it for anything.

Key chip is clean. Sometimes it'll crank and start.

Other times it won't.

Right this minute, it won't.

I know what the codes mean. I just don't know why it started doing it all of a sudden.

Security light stays solid when I turn the igniition.
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Old Oct 4, 2023 | 05:12 PM
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If the security light is solid when trying to crank, the VATs has been tripped. Code 46 seems to back this up. The easiest thing to do (in my opinion) is to get a resistor with the same resistance as your key, and put it in the car side of the VATs connector, to trick the car into seeing the "key" at all times.
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Old Oct 4, 2023 | 05:17 PM
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Originally Posted by sheriffjim
If the security light is solid when trying to crank, the VATs has been tripped. Code 46 seems to back this up. The easiest thing to do (in my opinion) is to get a resistor with the same resistance as your key, and put it in the car side of the VATs connector, to trick the car into seeing the "key" at all times.
Thanks. Thatr seemed to be the most common thought on it when I was looking around before asking.

I don't even know where to begin with doing that kind of work though. Don't really trust the mechanics around here either.
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Old Oct 4, 2023 | 05:21 PM
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Originally Posted by Natty C
Thanks. I don't even know where to begin with doing that kind of work though. Don't really trust the mechanics around here either.
It's pretty easy. Just take down the hush panel on the drivers side and look for the vats connector. I'm sure someone here has a good picture, and if you have a service manual you should be able to find one. It's a two-wire connector. Just unplug it and put your resister in the plug on the car side, and that should be it.

You can find the resistor you need by measuring resistance over the prongs on the key resistor with an ohm meter.

I believe there are some youtube videos of the process that can probably help a lot better than I can.
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Old Oct 4, 2023 | 05:29 PM
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Originally Posted by sheriffjim
It's pretty easy. Just take down the hush panel on the drivers side and look for the vats connector. I'm sure someone here has a good picture, and if you have a service manual you should be able to find one. It's a two-wire connector. Just unplug it and put your resister in the plug on the car side, and that should be it.

You can find the resistor you need by measuring resistance over the prongs on the key resistor with an ohm meter.

I believe there are some youtube videos of the process that can probably help a lot better than I can.
Yeah, I already dropped the hush panel and I unplugged the connector to see if it was loose or whatever. So I at least know what I'm looking at.

I'll check on youtube ot something to see how to measure the key resistance.

I never had this problem until I had the top of the column apart.

Thanks.
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Old Oct 4, 2023 | 05:44 PM
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Well I set my meter to 20k like they did in the video and got 1.46

But it;s just a number to me.

I've no idea what it actually means in the scheme of things. lol.
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Old Oct 4, 2023 | 06:07 PM
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Alright. So, then, basically this is what I need to do. I got it. Hopefully that does the trick. Thanks,

​​​​​​
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Old Oct 4, 2023 | 06:14 PM
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1.46 should be code 6. (Min 1.41 - Max 1.54 - Target 1.47)
That's 1.46k or 1460 ohms of resistance. You'll need to buy a resistor with that same resistance, it should cost less than a dollar.

Basically the ECM is going to send a reference voltage through the lock cylinder. The resistor on your key completes the circuit but introduces a set amount of resistance to the circuit as well. The ECM will see the "return voltage" coming out of the lock cylinder, and if that voltage is in range the car will start. If you try to start the car without a VATs key, or with the wrong code, the ECM will see an out-of-range return voltage and the car will not start.

By unplugging the lock cylinder and shorting the plug with a resistor, you are effectively permanently completing the circuit while still maintaining the correct resistance. That way, when the ECM interprets the return voltage it will be in range and the car will start.


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Old Oct 4, 2023 | 06:20 PM
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Originally Posted by Natty C
Alright. So, then, basically this is what I need to do. I got it. Hopefully that does the trick. Thanks,

​​​​​​https://youtu.be/3PkHTxDQpkE
Yes that's exactly what I'm talking about! I don't think you need to cut the wires like he did, although you can if you want to. (That may even be better/more reliable than what I did.). On my car, though, I just unplugged it and stuck the resistor into the plastic connector. The resistor had pretty long leads on it so I was able to get a pretty secure fit, and I was able to bury the leads far enough in there I'm not worried about them shorting to anything/being pulled out.
But that is only my experience, and just something to consider.

Good luck, I hope it works for you!
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Old Oct 4, 2023 | 06:35 PM
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Originally Posted by sheriffjim
Yes that's exactly what I'm talking about! I don't think you need to cut the wires like he did, although you can if you want to. (That may even be better/more reliable than what I did.). On my car, though, I just unplugged it and stuck the resistor into the plastic connector. The resistor had pretty long leads on it so I was able to get a pretty secure fit, and I was able to bury the leads far enough in there I'm not worried about them shorting to anything/being pulled out.
But that is only my experience, and just something to consider.

Good luck, I hope it works for you!
I'll try to mess around with it over the weekend. Everything's apart, so just a matter of the resistor.

I'm not gonna cut it either. I'm just gonna do it the same way you did.

Thanks for you help, though. I appreciate it.
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Old Oct 4, 2023 | 06:36 PM
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No problem! I hope it works!
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Old Oct 5, 2023 | 12:20 PM
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I'm having a problem finding this darned resistor. There's just no true electronics stores around any more.

I called the computer repait guy and the best he can do is put three resistors together but that would put me at 1500. Which is on the high side.

He can put two together but that's on the lower end.

Nothing in the middle where I need to be.
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Old Oct 5, 2023 | 02:29 PM
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In the mean time, I pulled the wheel just so I could figure out with absolute certainty what's going on.

It was either that or cut the lawn, which I've been putting off for two days already. I still don't feel like cutting the lawn yet. I'll do it tomorrow.

Anyway. Now I know. No room to make a repair. It figures the wire broke where it did.

So...lesson here for any casual passers-by is if you ever have to pull your upper column apart and the ignition cylinder has to be removed, be careful not to let it fall out and dangle around under its own weight. Because I'm positive that's what did it.



But...now I don't feel like putting the wheel back together. So I guess I'll cut the grass instead.
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Old Oct 5, 2023 | 03:23 PM
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Or
Amazon Amazon
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Old Oct 5, 2023 | 04:20 PM
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Not sure about a 90 but according to the FSM an 87 can not be push started with a vats problem.

.

Last edited by Vets-Vet; Oct 5, 2023 at 04:27 PM.
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Old Oct 5, 2023 | 05:57 PM
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Ah yeah. I wasn't able to find anywhere selling resistors either. I ended up buying off amazon.
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Old Oct 6, 2023 | 01:54 PM
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Newark Electronics is the place you want to go for electronic components. Just make sure you watch for delivery dates as sometimes they are extended. Numbers are sometimes misleading on the internet, instead of 1047, it was 1.47kohms that you needed to search for. The below resistor is 1/4 watt (250mW) so make sure the wattage is correct for what you need, and it is a whopping 89 cents . At Newark the menu on the left side of the page is used to narrow the selection.

https://www.newark.com/neohm-te-conn...tor/dp/98K3511
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Old Oct 13, 2023 | 02:04 PM
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Originally Posted by sheriffjim
No problem! I hope it works!
Started right up. Thanks again!

I found resistors that were precisely 1.47k

So now I'll keep a casual lookout for a used replacement ignition cylinder and key that has the same resistance as mine and do a proper repair at some point down the road.

But...for now, it's rolling again.
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