passlock2 bypass, cannot retrieve r value

99 Suburban with faulty passlock2 system.
Bypass instructions say clip yellow wire, read resistance value between yellow keyside and ORANGE / black.
Problem is, resistance is showing 50 mega ohms.
So, I'm assuming the ignition passlock circuit is open.
Truck won't start, just fires and dies, security light on.

How do I figure out what resistance value the ECM needs?

current state:

If the internal Passlock2 part of the ignition cylinder has gone bad, it needs to be replaced or...
Do you want to keep the Passlock2 immobilizer system working or bypass it completely?


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Soldering is fun!

I want to bypass completely.

the wire nuts are not me. I'm going to fix that with barrel crimps and moisture resistant heat shrink tubing.

Ok. Here is a previous post that will make your life easier :
https://www.the12volt.com/installbay/forum_posts.asp?tid=123309&KW=racing%5Fbidule
Follow the steps outlined by racing_bidule

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Soldering is fun!

I agree with kreg. Here's an old post I made that has the same information, but with more detailed steps.

Look at post #6:
https://www.the12volt.com/installbay/forum_posts.asp?tid=72296&KW=Chris+Luongo

Essentially, what you really need is a new Passlock switch, and after installing it, if you don't have a GM scan tool, there's a self-learning procedure that takes 30+ minutes to complete.

However, instead of installing a new switch, you can just install a resistor and the car will "think" the switch has been replaced. Of course, the car will now be easier to steal than before, and you may risk some troubles with your insurance company if the car ever gets stolen. But on the positive side, the car thief isn't going to know that you have the only GM car in town without Passlock; the car will look and run just as before.

TIP: You're going to have the ignition on for 30 minutes or more during this. At a minimum, you'll want to turn off the radio, front/rear climate controls, and try to disable the automatic headlights. Even better if you can hook up to a battery charger.

Great step by step instructions, Chris! ( Why couldn't I find that with my search? ) I will definitely book mark it for reference and future posts. Those Passlock2 systems aren't getting younger...

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Soldering is fun!

Well, I soldered in a 1k resistor and tried the re-learn.
No difference. Just starts for second and dies. The security light is lit solid, no blinking (not sure if that makes a difference).
I checked the resistor before installing and got a value of 975 ohms. Is there a chance this too low for the ECM to recognize?

Most any resistor value should work.
The three failed start attempts with the key left ON for 10 minutes after each is supposed to re-learn the new resistor value to the BCM. The BCM then looks for this new resistor value from then on.

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Soldering is fun!

Hmmm, that's what i did but no worky.
now the battery voltage is low. I have it charging now.
I'll do capacitive discharge on the batt cables and try again when the battery is charged.

I can't get the security light to go off. No amount of re-learn helps. I went from a 1k to 2k resistor and tried again, but nothing. Same result. Security light is solid on every time the key is in the ignition.

I just had a thought though- I pulled a large fuse for the lighting system to help the battery. I'm wondering now if the security system needs this fuse installed to function properly.

Got it fixed. The problem was self-inflicted. I pulled the "lighting" fuse to save the battery, since the headlights come on with the key in the run position. Apparently the security system was tied into that fuse. With the fuse pulled, the security light came on but never flashed. With the fuse installed, the security light blinks and the re-learn worked.
Thanks to everyone that helped me solve this.

    

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Soldering is fun!