PASSLOCK PROBLEM

2003 GMC Sierra

Tiny

szalkuskt

April, 16, 2010 AT 11:19 PM

Electrical problem
2003 GMC Sierra V8 Two Wheel Drive Automatic 10500 miles

i have a 03 gmc sierra dually 3500 and it has a 8.1 v8. I have the padlock warning light on bright steady sometimes and the truck will take forever cranking then eventually will start. I will think the passlock system is the problem. What do you all do to solve this bypass it or replace something?

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45 Answers

Tiny

BMRFIXIT

April, 19, 2010 AT 6:33 AM

Check for trouble codes 1st
Very common failure is the ignition switch
If have another key try that 1st as ignition key maybe at fault (not very common but possible)
Lock smith can help you in replacing the ignition and programming the keys

Tiny

szalkuskt

April, 21, 2010 AT 1:00 AM

On this particular truck the resistor stuff is inside the lock cylinder for the ignition. It is passlock II. 2003 sierra. The key is a normal key. There are no OBD2 trouble codes. Maybe changing the ignition lock cylinder is the fix I can't tell.

Tiny

BMRFIXIT

April, 21, 2010 AT 6:21 AM

Need the use of a scanner as an OBDII will only get P codes you are looking for B codes
Ignition switch is more common to fail and need codes to conform suspicion
Try and do 30 Minute Learn Procedure
Turn ON the ignition, with the engine OFF.
Attempt to start the engine, and then release the key to ON, vehicle will not start.
Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF.
Turn OFF ignition, and wait 5 seconds.
Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes, the vehicle is now ready to relearn the Passlock√ Sensor Data Code and/or Passwords on the next ignition switch transition from OFF to CRANK.
IMPORTANT: The vehicle learn the Passlock√ Sensor Data Code and/or Password on the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.

Start the engine. The vehicle has now learned the Passlock√ Sensor Data Code and/or password.
With a scan tool, clear any DTCs if needed. History DTCs will self clear after 100 ignition cycles.

Tiny

BMRFIXIT

April, 22, 2010 AT 7:10 PM


http://www.2carpros.com/forum/automotive_pictures/99387_Graphic_65.jpg



http://www.2carpros.com/forum/automotive_pictures/99387_Graphic1_711.jpg



http://www.2carpros.com/forum/automotive_pictures/99387_Graphic2_325.jpg



http://www.2carpros.com/forum/automotive_pictures/99387_Graphic3_142.jpg



http://www.2carpros.com/forum/automotive_pictures/99387_Graphic4_63.jpg



http://www.2carpros.com/forum/automotive_pictures/99387_Graphic5_38.jpg

Tiny

szalkuskt

April, 22, 2010 AT 7:32 PM

Thanks for the photos. I am wondering is the ignition switch separate from the ignition cylinder? Also, do you have a diagram relating to the procedures for removal of the components described in your reapair steps?

Tiny

BMRFIXIT

April, 22, 2010 AT 9:18 PM

You have an ignition switch and ignition cylinder lock

Need special tool


http://www.2carpros.com/forum/automotive_pictures/99387_Capture1_5.jpg

Tiny

szalkuskt

April, 23, 2010 AT 2:42 AM

Can I just install an ignition switch and try and see if it fixes the problem? Is the special tool for removing the ignition lock cylinder? Also can't you just use an allen key wrench or something to remove the ignition lock cylinder?

Tiny

BMRFIXIT

April, 23, 2010 AT 6:47 AM

Most common to be the switch and not the cylinder lock
Inspect closely the wiring harness too
You can use whatever available to you and make your own special tool knowing what it look like

Tiny

szalkuskt

April, 23, 2010 AT 12:18 PM

I don't understand what exactlyy goes bad with the switch. Is it a mechanical switch or inductive? Where is the passlock resistor in the cyl lock? I have a switch I bought on order. I was thinking change that first. Anything special to do after changing the ign switch?

Tiny

BMRFIXIT

April, 23, 2010 AT 5:09 PM

I strongly recommend having it scanned for codes
Scan BCM codes its B codes and not P codes

The Passlock√ system is provided in order to prevent vehicle theft if the ignition lock cylinder is forced to rotate or the ignition switch is operated while separated from the ignition lock cylinder case. The body control module (BCM) provides security system sensor power and low reference for the Passlock√ sensor. The BCM also measures the security system sensor voltage.
When the correct key is used to start the vehicle, a magnet on the lock cylinder passes close to the Passlock√ sensor within the ignition lock cylinder case. The magnet activates the security hall effect sensor in the Passlock√ sensor which completes a circuit from the security sensor signal circuit through a resistor to the security sensor low reference circuit. The resistance value will vary from vehicle to vehicle. The BCM will measure the voltage on the security sensor signal circuit and compare this voltage to a previously learned voltage. If the voltage measured is within the valid range, the BCM will send a class 2 message to the powertrain control module (PCM) to enable vehicle starting. If the voltage measured is not within the valid range, a class 2 message will be sent to the PCM to disable starting of the vehicle.

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