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MPMoore, ASE Certified Technician
Category: Oldsmobile
Satisfied Customers: 2956
Experience:  GM world class tech/ ASE master tech with L1.
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2004 Olds Alero: wont system..a no crank

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2004 Olds Alero wont start has had flashing security lamp in dash on occasion,went to start this AM and it indicates A continuous flashing security lamp owners book says a problem with pass lock what is this as there is no security system in this car that I know of.
it is a no crank no start situation.


MPMoore :

The security system on this car is for the ingition key. The ignition lock has a system called pass-lock. This system stops the car from starting if the lock cylinder is tampered with. Does your ignition lock turn with any problems?

Customer: replied 6 years ago.
The ignition feels and acts as it always has however as always when you turn the key to the crank position there is a momentary delay in the response and then it cranks

The passlock sensor is more then likely starting to go bad. You can try and reprogram it so that you can start your car. This some times fixes the concern for a short time before it acts up again. Here is the procedure, make sure you follow each step, if its not done correctly it will not work. Its also a good idea to set the parking brake before you turn the key on, this keeps the headlamps off while the program learns.



  1. Turn ON the ignition, with the engine OFF.
  2. Attempt to start the engine, then release the key to ON (vehicle will not start).
  3. Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF.
  4. Turn OFF the ignition, and wait 5 seconds.
  5. The vehicle is now ready to relearn the PasslockTM Sensor Data Code and/or passwords on the next ignition switch transition from OFF to CRANK.

    Important: The vehicle learns the PasslockTM Sensor Data Code and/or password XXXXX the next ignition switch transition from OFF to CRANK. You must turn the ignition OFF before attempting to start the vehicle.

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




Customer: replied 6 years ago.
If this doesn't work I assume the passlock sensor must be replaced ?

Yes, its part of the ignition lock cylinder. Its not a hard job, but the new lock cylinder is not coded. The lock cylinder comes in two parts, one is the pass lock sensor and the other is the lock barrel. You do not have to use the new lock barrel, you can use the old one. This way you do not have to recode the new cylinder. The new cylinder does come with all parts you will need to recode it and some instructions as well if you want to replace it.

I'm on my way home, I will check back with you in about 30 mins.

MPMoore and other Oldsmobile Specialists are ready to help you
Customer: replied 6 years ago.
Thanks for your help I should be able to fix this.