Chevy Anti-Theft

[adsm08]

Does anyone know the specifics of Chevy's anti-theft systems?

I have an 02 S-10, 4.3L, auto, 4x4. I just finished putting an engine in it (that is a whole other story) and it won't start. I believe the starter is a problem, as it works intermittently, but when it is working, here is what it does.

The security light comes on, then goes off after a few minutes. After this it will crank, two or three times, then it won't even try to engage the starter (which I can still do manually by jumping power to it). When it is cranking it will not even try to start on its own, but the fuel pump does prime and the engine will catch on ether.

I plan to play with the security reset tomorrow, but the crux of my question is this:

Is this security system a starter inhibit, an injector inhibit, a fuel pump inhibit, or some combination of the three?

 

[RonD]

GM use PassLock I or II system.
'02 would have II and starter disable, injector disable and fuel pump disable.

PassLock uses a Resistor in the key.
The passlock module(BCM) sends 5 volts to the key cylinder then reads the return voltage to determine if the "key" is the correct one, correct resistor drops voltage a specific amount.

Problem with the system is the voltage variance over time and the cylinder wearing out.

Google: disable gm passlock ii system

You can solder in a resistor to bypass key cylinder.
Use a good digital OHM meter to see what resistance the key has, get a resistor of that value to solder in place.
You can also "relearn" a new resistor value to the system.

To fix PassLock system usually runs from $400 to $800, key cylinder is $250

 

[adsm08]

Yeah, I did the half hour of key on while I was cleaning up and it didn't help at all. Swapped the starter relay with the rear defrost relay, truck starts and runs now.

Thanks for the info though Ron.

 

[adsm08]

Back to the drawing board. After having it running on the ramps this morning I went to do other things.

Came back this afternoon, it fired right up, dies when the brakes are applied and now I can't get it to start again.We are back to no-crank from the key.

So very glad this is not my truck.

 

[RonD]

Is Security Light flashing?

Look at the top metal part of the key, if it has PK3 stamped in it then it will be a PassLock III system.

Google: passlock III bypass

Seems the key cylinders are almost always at fault with these, PK1, PK2 and PK3

 

[adsm08]

I will check the key in the morning.

More things I have learned about passlock today.

1) If you don't reset it properly you get a limited number of starts in a day.

2) To fully reset the system it seems you have to get it running, shut it off, then do the relearn two more times.

3) The brakes killing the engine can be a symptom of an unhappy passlock system.

4) This is apparently the most useless security system in the world. About the only thing it seems to protect against is theft by swapping key cylinders.

 

[cammeddrz]

^^unless you have the proper bi-directional scan tool to set it.

A $10 ebay part, placed on the wire to the PCM will defeat the entire system, the little module merely puts out the same 50hz. square wave signal that the pass lock sends once it sees an acceptable resistance from the resistor in the key.

 

[adsm08]

I have a bi-direction scanner (Solus) I just don't have the right software to reset security systems. I want to update to the latest software package but it's hard to stomach $1000 just for software I will probably use once or twice.

 

[cammeddrz]

A scan tool without the updates is like a ratchet without sockets.

 

[adsm08]

It is updated through 2012, but Snappy scanners didn't do security stuff and key programming until this most recent update, which is the last one my hardware will support.

And to be fair, I didn't buy this to work on OBDII vehicles, I bought it for it's EEC-IV capabilities. The shop I was working at when I bought it had a Solus Pro (with the same software package I have), but since I do work on cars professionally anymore it is really hard to stomach a grand for updates right now.

I think the newest thing I have touched since I quit the shop was my dad's 06 Explorer and that just needed some wheel bearings.

 

[cammeddrz]

Get the ebay module, put it on the right wire, and PassLock is forever defeated.