GMC Yukon 2000–2006
Common on this vehicle:
Possible causes
The documents say what to doOnly records name itThe size of a node, the width of a link and the numbers are records matching this search, not likelihoods.
FaultCrate・GMC Yukon 2000–2006・Security light, P2101
Candidate cause (the documents say what to do)
Passlock theft deterrent: starts then stalls / no-start with security lamp
A magnet in the ignition cylinder produces a unique voltage across a Hall effect sensor in the ignition housing; the BCM and lock cylinder enable starting.
If the voltage matches the stored value, the BCM signals the PCM to enable fuel.
How to tell
B2960P1631Security light
What to do
- A security lamp flashing after an attempted start means the fuel disable command is active.
- A scan tool parameter showing 'fuel system disabled' or similar indicates a Passlock issue.
- Monitor the Passlock Data Voltage for approximately one minute; the voltage value should not change by more than .02 volt.
- If the voltage does not change from 5 volts, check the ignition housing.
- The condition is the Security lamp illuminated on the instrument panel, engine stalls or no start, with DTC B2960 (Security System Sensor Data Incorrect but Valid) set; the correction is to inspect and repair the cause of DTC B2960.
Caution: Loss of Ignition 1 voltage to the BCM gives the same start-then-stall behaviour.
What is needed
- Parts and materials
- Not stated
- Labor time
- Not stated
- Special tools
- Not stated
- Scan tool
- Not stated
Only what the technical documents state. "Not stated" does not mean not needed.
In the records
No record states work done for this cause.
Outside the documents and the records
None of the four pages read is a record of the Yukon or Yukon XL. Two are a shop's records of the Hummer H3 (model year not given; not a vehicle of the Yukon's family), and two are Q&A threads on the Silverado (2001 and 2004). The 2001 Silverado thread holds only questions and advice, with no repair outcome reported.
- Sky Auto writes, in two Hummer H3 records (2017 and 2024), that a vehicle whose engine sometimes would not start showed a Passlock (security) fault on the diagnostic computer and that the Passlock module was replaced. スカイオート（埼玉）スカイオート（埼玉）
- In its two Hummer H3 records (2017 and 2024) Sky Auto explains that the Passlock module is in effect the ignition switch, and writes that the replacement starts by taking off the steering wheel and works inward from there. スカイオート（埼玉）スカイオート（埼玉）
- In its two Hummer H3 records (2017 and 2024) Sky Auto writes that the engine would not start on the module swap alone and that the job was finished with programming after the swap (described as registering the Passlock in the 2017 record). The 2024 record adds that the engine was then confirmed to start. スカイオート（埼玉）スカイオート（埼玉）
- The owner of the 2004 Silverado (4.3L) on 2CarPros writes that the engine started and died after about two seconds with the security lamp looking normal and no codes stored, that the cause was the Passlock sensor, and that it started after a 30-minute relearn (whether the sensor was replaced is not said). 2CarPros
The sentences above were written by FaultCrate from what shops' public pages and Q&A sites state as fact (none of the pages' wording is shown; a second reader checked each against its pages). A record of another vehicle says which vehicle. A Q&A thread is a question and advice, and may not say how the repair ended. The links below are places to look; the contents of pages not read were not checked.
The pages read, and other places to look (12)
Shops' repair records
- ハマーH3 エンジン始動不良修理スカイオート（埼玉）, Hummer H3, 2017
- ハマーH3 セキュリティスカイオート（埼玉）, Hummer H3, 2024
- GM ハマーＨ２ 電装系トラブル パスロックシステム解除 車両診断テスト エラーコードリセットグーネットピット, Hummer H2, not read
Repair videos
- 99 Silverado Starts and Dies code P1631 B2960 - Passlock Theft System 30min Learn No ToolsYouTube, 1999 Silverado, not read
- Chevy Silverado Tahoe Suburban Truck Van Cranks No Start Passlock Anti-Theft VATS Module TESTINGYouTube, Silverado / Tahoe / Suburban, not read
- How to Reset Antitheft Passlock Light in your GM - Chevy GMC Silverado Sierra TahoeYouTube, Silverado / Sierra / Tahoe, not read
Forums and Q&A
- Engine starts and then stalls while driving?2CarPros, 2004 Chevrolet Silverado 4.3L, 2016
- 2001 Chevrolet Silverado Security2CarPros, 2001 Chevrolet Silverado, 2013
- Security Light Issue - SOLVEDtahoeyukonforum.com, no vehicle stated, not read
- 2002 Tahoe wont runtahoeyukonforum.com, 2002 Tahoe, not read
- passlock security systemtahoeyukonforum.com, no vehicle stated, not read
Owners' records
- 2001 Chevrolet Suburban: Passlock system failure - car turns over but won't startCarComplaints.com, 2001 Chevrolet Suburban, not read
See the evidence (1 technical documents, 0 records)
Passages of the technical documents
A magnet in the ignition cylinder produces a unique voltage across a Hall effect sensor in the ignition housing; the BCM and lock cylinder enable starting.
The GM VTD or Passlock system uses the body control module (BCM) and ignition lock cylinder to activate the start function. The ignition cylinder uses a magnet that produces a unique voltage value when rotated in the ignition housing across the Hall effect sensor.
MOTOR Magazine 2006-04-01
If the voltage matches the stored value, the BCM signals the PCM to enable fuel.
The BCM compares this voltage value to the value stored in the BCM. If the voltage values are the same, the BCM sends a signal to the powertrain control module to enable fuel.
MOTOR Magazine 2006-04-01
If the values do not match, the engine briefly starts and then stalls.
If the voltage values are not the same, the engine will briefly start, then stall.
MOTOR Magazine 2006-04-01
A security lamp flashing after an attempted start means the fuel disable command is active.
The quickest way is to look at the security indicator lamp on the instrument panel. If it’s flashing after an attempted start, the fuel disable command has been energized.
MOTOR Magazine 2006-04-01
A cause or a result a complaint states is the owner’s view or what a dealer told them, not an established fact.
Put together by FaultCrate from public records and technical documents. The cause and the repair are for the workshop to decide with the vehicle in front of it. Counts are records, not failure rates.