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John, Buick Master Technician
Category: Buick
Satisfied Customers: 9176
Experience:  ASE A1-A8 w/L1 GM master technician.Factory certified with 40 years experience.
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2003 buick century: security light comes on at times

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my 2003 buick century 74kmi is not starting. does nothing at all. security light comes on at times. disconnect battery and wait 3 min usually does it. one key starts better than the other. cleaned keys. sprayed two shots of cleaner in ignition. sometimes pulling several pcm fuses does it. today first time will not start at all regardless. what do i need to do to get this trouble corrected? no codes showing. no other trouble. thank you. 3.1eng.

Hello & Welcome to JA,


Make sure your battery cables are clean (the mating surface/) & your battery will pass a load test.

Have you done this ?

Customer: replied 5 years ago.
battery connections clean. no load test done. i can change the battery. headlites strong. car is not TRYING to start due to computer killing everything. ignition is not engaging starter solenoid at all. i have 35 yrs locomotive troubleshooting for ns rr. pulling pcm fuses and reinserting usually starts car. rebooting with batt disconnect usually starts car. no indication i can see that battery is problem. starter not dragging ever. start is immediate once computer allows it. i can change battery easily but i dont think i am seeing battery trouble. i think problem is in  the security circuit disallowing the start signal from the computer??   red security light on alot.
Ok,very good information & needed. Your problem can be a theft deterrent system fault & one will need to view a scan tool for the BCM & PCM data parameters . This will show any faults & will show where command to start is lost or not prompted.
Customer: replied 5 years ago.
scan tool showing no faults. i have alldata access on this car. could not find helpful info on this problem on alldata. where can i get info on bcm, pcm parameters for this theft deterent problem? securtiy section alldata has little info. where in alldata should i look for help troubleshooting this?
where you looking at PCM or BCM ?
Customer: replied 5 years ago.
i was looking at the security theft deterent section which isnt much.
Scan Tool Data List

Scan Tool Parameter

Data List

Units Displayed

Typical Data Value

Operating Conditions: Ignition in ON, Engine OFF

Auto Learn Timer

Security Data



His. DTC Cyc. Counts

Security Data



Lock-out Timer

Security Data



Passkey Data Voltage

Security Data



Security Lamp State

Security Data



Seed and Key Timer

Security Data




Scan Tool Data Definitions Lockout Timer: The duration of time the system remains in tamper mode The VTD system will disable sampling of the key code for 3 minutes when a tamper is detected.

Auto Learn Timer: The duration of time the system remains in the re-learn wait mode.

Seed and Key Timer: The scan tool displays the time in seconds used by the BCM to learn a valid code from the passlock sensor. The learn procedure consists of 3 seperate periods.

Passkey Data Voltage: Displays the voltage data from the Passkey Sensor to the BCM. The BCM determines if the data received is valid or invalid.

Security Lamp State: Indicates the state of the SECURITY indicator either On or Off.

His DTC Cyc. Counts.: Displays the number of key cycles that have occured in order to clear history DTCs.




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Customer: replied 5 years ago.
do i need more than a simple obd 2 scan tool? mine has alot of features, about 200$ tool. will this enable me to troubleshoot this or will i need to go to someone with tech 2 equipment?
Yes, you will need a tool that will access BCM data also

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