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Jerry
Jerry, Master Mechanic
Category: GM
Satisfied Customers: 13427
Experience:  ASE Master tech, 30 years experience GM certified
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2000 OLDS ALERO: CAR WONT..START...THIS HAPPENED THE SECURITY LIGHT

Customer Question

I BOUGHT A 2000 OLDS ALERO FROM A MECHANIC AND EVERY OTHER DAY OR SO THE CAR WON'T START. I BROUGHT IT BACK TO HIM AND HE COULD NOT FIND OUT WHAT THE PROBLEM WAS. WHEN THIS HAPPENED THE SECURITY LIGHT ON THE DASH WOULD FLASH. THE MECHAQNIC HOOKED THE CAR TO THE DIAGNOSTIC CENTER BUT NO CODES CAME UP. HE DID CHECK THE OWNERS MANUAL THOUGH AND CAME UP WITH A PARAGRAPH THAT STATES THAT IF YOU DO ENCOUNTER THIS PROBLEM TO LEAVE THE IGNITION IN THE ON POSITION FOR SEVERAL MINUTES UNTIL THE SECURITY LIGHT STOPS FLASHING AND THEN THE PROBLEM WILL RESET ITSELF AND THE CAR WILL START. THIS REMEDY WAS CORRECT. IS THIS SOMETHING THAT I HAVE TO LIVE WITH FOR AS LONG AS I OWN THE CAR OR IS THERE A REAL CORRECTION FOR THIS PROBLEM
Submitted: 5 years ago.
Category: GM
Expert:  Jerry replied 5 years ago.

Hello and welcome to Just answer.com, Super mechanic here. About your vehicle.

 

When there are no trouble codes to go by and the system has to be relearned more than one or two times, what I do is replace the ignition lock cylinder, (with the passkey sensor in it) and that seems to work out most of the time.

 

Of course, you will want to get the new cylinder from the dealer and have it coded to your original key and then do the relearn on it.

 

 

You must perform a theft relearn procedure if any of the following components have been replaced:

  • Passlock sensor
  • Body control module (BCM)
  • Powertrain control module (PCM)

The above modules, with the exception for the Passlock Sensor must also be programmed with each module's own vehicle configuration.

Auto Learn
Time required, approximately 30 minutes.
  1. Insure that the battery is fully charged.
  2. Use the scan tool in order to clear the DTCs.
  3. Turn the ignition switch from the OFF position to the CRANK position attempting to start the vehicle. The vehicle will start and then stall.
  4. Leave the ignition switch in the ON position while observing the security indicator.
  5. When the security indicator turns off, which can take up to 10 minutes, turn the ignition switch off. Wait 10 seconds.
  6. Repeat Steps 3 through 5 two more times (3 times total).

The BCM and the PCM will learn the new code on the next start attempt.

 

 

Customer: replied 5 years ago.
I GUESS I NEED TO BRING THE CAR BACK TO THE MECHANIC TO DO THE RELEARN, RIGHT? HOW ABOUT IF I TRY TO DO THE RELEARN MYSELF, WOULD IT HAVE TO BE DONE AT THAT TIME WHEN THE CAR WILL NOT START OR CAN I JUST GO THROUGH THE RELEARN PROCESS ARBITRARILY WHEN I HAVE A HALF HOUR OR SO TO SPARE
Expert:  Jerry replied 5 years ago.

If the engine starts then it is getting the correct reading from the passkey sensor. You can only relearn it when it is not starting. If you encounter the problem then you can do it yourself, but you may want to see if he/she will replace the lock cylinder for free or a discount to you.

 

 

You must perform a theft relearn procedure if any of the following components have been replaced:

  • Passlock sensor
  • Body control module (BCM)
  • Powertrain control module (PCM)

The above modules, with the exception for the Passlock Sensor must also be programmed with each module's own vehicle configuration.

Auto Learn
Time required, approximately 30 minutes.
  1. Insure that the battery is fully charged.
  2. Use the scan tool in order to clear the DTCs.
  3. Turn the ignition switch from the OFF position to the CRANK position attempting to start the vehicle. The vehicle will start and then stall.
  4. Leave the ignition switch in the ON position while observing the security indicator.
  5. When the security indicator turns off, which can take up to 10 minutes, turn the ignition switch off. Wait 10 seconds.
  6. Repeat Steps 3 through 5 two more times (3 times total).

The BCM and the PCM will learn the new code on the next start attempt.

Jerry, Master Mechanic
Category: GM
Satisfied Customers: 13427
Experience: ASE Master tech, 30 years experience GM certified
Jerry and 10 other GM Specialists are ready to help you
Customer: replied 5 years ago.
COULD THIS HAVEBEEN TRIGGERED BY THE BATTERY DYING AND THE CAR BEING DEAD FOR AWHILE? HE HAD TROUBLE INSPECTING IT BECAUSE OF THE DEAD BATTERY, HAD TO DRIVE THE CAR FOR HOWEVER MANY MINUTES BETWEEN 50 & 60 MPH BEFORE IT WOULD PASS. JUST WONDERING IF THAT COULD BE WHY.
Expert:  Jerry replied 5 years ago.
Not normally. I have had some that the batteries died while doing the relearn but it never had any effect on it. That reminds me, you will want to have a charger on it, (or a jumper) while doing the relearn. Even with a good battery, they can draw a pretty good amount of current and weaken it. However, once the battery has been fully charged and the engine is running, there should be no problems with the passkey system from the battery dying, thanks
Customer: replied 5 years ago.
THE ONLY THING THAT I AM NOT QUITE UNDERSTANDING NOW IS- WHY DOES THE CAR START AFTER LEAVING IT IN THE ON POSITION FOR THE FIRST UP TO TEN MINUTE TIME PERIOD. I AM ONLY ASKING THIS SO THAT I AM SURE THAT INSTALLING A NEW LOCK CYLINDER WILL ALEVIATE THE PROBLEM AND IN ANTICIPATION OF MY MECHANICS QUESTION.
Expert:  Jerry replied 5 years ago.
Description and Operation
Notes

The vehicle theft deterrent system is designed in order to prevent vehicle theft by disabling the fuel injectors unless the lock cylinder is correctly engaged by a mechanical key. The theft deterrent system uses the following 4 components for theft prevention:

  • The lock cylinder
  • The ignition switch
  • The body control module (BCM)
  • The powertrain control module (PCM)

When starting the engine, the PCM searches for a password XXXXX the BCM through the Class 2 serial data circuit. If the password XXXXX XXXXX recognized or not present, the PCM will disable the engine. Two modes of tamper detection are provided:

  1. No password XXXXX The engine will start and stall quickly. SECURITY telltale will flash on the instrument panel cluster (IPC) and then stay ON steady.
  2. Incorrect or disable password XXXXX (More than 3 invalid passwords are received) The engine is disabled for at least 10 minutes and the SECURITY telltale will illuminate solid on the IPC during the 10 minutes.

After the vehicle has passed theft detection, the PCM will continue normal operation.

Ignition Switch
The mechanical key and lock cylinder is located in the instrument panel assembly. The electrical switching portion of the assembly is separate from the key and lock cylinder. Both of the components are synchronized and work in conjunction through the action of the actuator rod assembly.

Passlock Lock Cylinder
The Passlock lock cylinder is a locking cylinder that turns a rotating magnet past a stationary hall effect sensor. This action creates the Pass/key cylinder data. The Passlock cylinder data is sent to the Body Control Module (BCM). The Passlock lock cylinder is interfaced with the BCM via a 3-wire connection:

  • Power
  • Ground
  • Data

Powertrain Control Module (PCM)
The Powertrain Control Module (PCM) is located on the lower left side of the instrument panel.

The PCM communicates with the Body Control Module (BCM) via serial data over the class 2 serial data bus, CKT 1807. When the BCM determines a passed theft condition, the BCM sends a coded password XXXXX the PCM. When the PCM receives the correct password, the PCM enables the fuel injection system, allowing the vehicle to operate correctly. The PCM may allow the car to start and quickly stall during a failed theft condition.

The following conditions may cause the PCM to enter a tamper mode:

  • A bad timing cycle
  • An incorrect password

If the BCM does not receive a password XXXXX a preset time window, the BCM will enter a short tamper mode. During this mode, the PCM will not allow the car to operate for 4 seconds.

If the password XXXXX XXXXX the PCM will enter the long tamper mode. In the long tamper mode, the following actions will occur:

  • The THEFT SYSTEM indicator will flash.
  • The fuel injectors will be shut off for approximately 10 minutes.

Although the vehicle may start, the engine will quickly stall due to a fuel cut-off.

In the event of an open in the serial data communication between the BCM and the PCM, the following actions occur:

  • The PCM will become fail-enabled if the car has already passed theft for that ignition cycle (i.e. the engine is running).
  • The PCM may set the diagnostic trouble codes (DTC).
  • The THEFT SYSTEM indicator will light continuously.
  • The PCM will become fail-enabled for future ignition cycles.

If a failure occurs in serial data before the ignition cycle, while the PCM is not fail-enabled, the PCM will never receive a valid password XXXXX order to enable the continued use of the fuel injectors.

Customer: replied 5 years ago.
THANK YOU FOR THAT DATA. I WILL PASS THAT ON TO MY MECHANIC. WHAT I AM TRYING TO SAY OR ASK IS THAT AFTER THIS HAPPENS THE CAR WILL START FINE FOR DAYS BEFORE DOING IT AGAIN, WILL CHANGING THE LOCK CYLINDER FIX IT ? I KNOW THAT I'M PROBABLY BEING THICK, AND I THANK YOU FOR YOUR TIME- THIS WILL BE MY LAST QUESTION- AGAIN, THANK YOU
Expert:  Jerry replied 5 years ago.

No problem, our goal is to help save you money, (not to mention some headaches)

 

I had a few that would do that same thing when they were fairly new and after the first (tow bill) the shop forman said, "replace the ignition lock cylinder" and then they were fixed. Some sort of internal thing with the passkey sensors, is what we determined.

 

I will be going to lunch, (hope n) but let me know if you need anything, I'm normally always workin' but later tonight I will be spending time with my little ones, (yep, I still have little ones, 12 and 14..at my age, LOL) I will prolly bring my laptop for when they get glued to the TV.

 

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