How to do away with factory passlock security system

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lester622

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Got my truck running the other day and reset the security light since i changed columns and wiring harnesses. Went to start it today and security light stayed on so looked around online and ran across this, its not the resistor mod which i didnt want to do this is much easier and involves a toggle switch.

http://www.gmupfitter.com/publicat/bull/bull26.pdf

The directions are how to bypass it for a remote start but can also be used to bypass the security
 

mattillac

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Got my truck running the other day and reset the security light since i changed columns and wiring harnesses. Went to start it today and security light stayed on so looked around online and ran across this, its not the resistor mod which i didnt want to do this is much easier and involves a toggle switch.

http://www.gmupfitter.com/publicat/bull/bull26.pdf

The directions are how to bypass it for a remote start but can also be used to bypass the security

From the bulletin:

....Any condition which removes battery power from the Vehicle Control Module/Powertrain
Control Module (VCM/PCM) (e.g. dead battery, disconnected harness connectors, etc.) will
prevent the vehicle from being restarted....

When battery power is removed from the vehicle the computer will reset and you will lose the failed enabled mode.
In other words the passlock components would need to be functioning in order to restart the vehicle(after a power loss),
to get into the failed enabled mode the vehicle must be running.

A more permanent solution would probably be to have the passlock feature tuned out/turned off at the vehicles computer.

Edit: I do have a switch installed on mine, originally I used it to troubleshoot the no start I had.
Now I simply use it as a kill switch for anti-theft, when I leave the truck I switch that circuit open,
that way even if someone got a hold of my keys the truck will only start for 2 seconds and then stall(going nowhere).
 
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lester622

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From the bulletin:



When battery power is removed from the vehicle the computer will reset and you will lose the failed enabled mode.
In other words the passlock components would need to be functioning in order to restart the vehicle(after a power loss),
to get into the failed enabled mode the vehicle must be running.

A more permanent solution would probably be to have the passlock feature tuned out/turned off at the vehicles computer.

Edit: I do have a switch installed on mine, originally I used it to troubleshoot the no start I had.
Now I simply use it as a kill switch for anti-theft, when I leave the truck I switch that circuit open,
that way even if someone got a hold of my keys the truck will only start for 2 seconds and then stall(going nowhere).

Seems like nobody tunes these computers anymore id like to get mine deleted but have been unable to find a person who does it. Idk about the battery being disconnected because mine was not running before i put the switch in it was in theft mode start for 2 seconds kill. After i put the switch in it still unable to reset the passlock it started fine and ran. Ima unhook the battery again and see if it works a second time. My light was not flashing it was just staying on.
 

Virginiabound

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With the TRUCK RUNNING, unplug the three-wire plug on the top of the ignition.

The security light will stay illuminated but it will allow the truck to be started from there on out without any worries.
 

lester622

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ok had the battery disconnected for 3 days and hooked it back up today and truck started up fine and no security light on the dash at all. So this is a way to get rid of the passlock deal.
 

mattillac

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ok had the battery disconnected for 3 days and hooked it back up today and truck started up fine and no security light on the dash at all. So this is a way to get rid of the passlock deal.

That security light not coming on seems really odd, especially considering the bulletin/mod says this:

When this modification is performed and the switch is set to the ON
position, the theft deterrent feature will be disabled. When the theft
deterrent is disabled the SECURITY telltale will light up indicating that
the theft deterrent system is NOT functioning.

Start the engine with the ignition key (modification switch must be in the OFF position).
Turn modification switch to the ON position (contacts open). The Security Telltale will
light up indicating that the Passlock System is inoperative.
Once the security telltale has
been on for at least 5 seconds the vehicle can be turned off and then remotely started.
http://www.gmupfitter.com/publicat/bull/bull26.pdf

Virginiabound also notes "...The security light will stay illuminated..."

Wonder if he has ever disconnected the battery on a vehicle which has that "three-wire plug on
the top of the ignition" unplugged, to verify whether that is a permanent fix or not.

The way I understand things is, disabling the passlock by unplugging the key portion or cutting the yellow
data wire(switch install)will eliminate annoying no start conditions related to and caused by the column parts of
the system, but only until the day the battery dies at which point the passlock will be need to be hooked
back up, only in order to restart the vehicle.

Wouldn't be the first time I was wrong though, glad to hear your up and running lester622.

One side note, since that mod is for a remote start a person needs to be careful if/when labeling that switch:
Connect the yellow wires to the switch such that the contacts are OPEN when the switch is in the ON position.....
Going by the directions for labeling that switch, notice that passlock would be OFF when the switch is in the ON position and ON when in the OFF position.
 

lester622

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Security light seems to be functioning right, when you turn the key on the light stays light to test the bulb then goes out like normal. Ive asked some of the older techs at work(chevy dealership) and they didnt have answer for the problem. I wonder if by putting the switch in or just cutting the wire if it just turns it off in a sence. I bought a new ignition switch and passlock sensor/housing because i kinda figured as well if battery was disconnected it would lose memory and reset itself. But it wouldnt be the first time where a dealer bullitin was wrong or misleading, seems to happen more often then youd think lol.
 

Virginiabound

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Mattillac-

I have actually drilled a 3/4 hole on top of the steering wheel cover and popped a flush rubber cap in, that way if it does need to be plugged in, reprogrammed and unplugged from a dead battery I can access the wires without any issue.

However, I have disconnected my battery during an hid install, approx ten minutes with the battery completely disconnected, and the truck started with the wires unplugged and untouched. I think it maintains memory off whatever device it is that retains your radio shortcuts and programmed stations.
 
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