B2960 Passlock / theft-deterrent security sensor fault (GM)

Passlock security sensor fault, security light on

B2960 in short

On Chevrolet, Saturn and Isuzu, B2960 means the theft-deterrent (Passlock) system does not accept the security sensor signal, so the security light comes on and the engine may not crank, start or keep running. GM bulletins point to the lock cylinder sensor or body control module connections. Get it diagnosed soon, and stop driving if it stalls.

GM's Passlock theft-deterrent system checks a sensor in the ignition lock cylinder. If the body control module (BCM) does not accept that signal, it stores B2960, turns on the security light and can disable starting. Isuzu owners quote the readout as "security system sensor valid but incorrect."

GM bulletins cover B2960 on 1999–2001 Silverado, Sierra and Tahoe and 1998–2001 vans (security lamp, engine stall, no start), on 2000–2005 Impala and Monte Carlo (security light, no crank; GM's fix is repairing poor terminal connections at the BCM), on 2000–2004 Saturn L-Series (intermittent security telltale) and on 2003–2006 Saturn Ion (no crank in cold weather, with B3033).

Owners also report technicians replacing the lock cylinder for a failing Passlock sensor. It is not an airbag code, but a stall while driving is a safety risk.

Pick your make

B2960 is a manufacturer-specific code: its meaning depends on who built the car.

Other makes: meaning not verified. Check with a scan tool that reads manufacturer definitions.

Most likely causes

  1. Passlock sensor or ignition lock cylinder failing

    Supported by vehicle data
    Why it ranks here
    A technician's readout quoted in a complaint calls B2960 a failing ignition Passlock sensor fixed with a new lock cylinder, and Isuzu readouts blame the key cylinder; GM has a Passlock B2960 diagnosis message.
    What would change this
    Rises if the security light flashes and the engine cranks but won't start. Falls if the fault follows a loose BCM connection.

  2. Poor terminal connections at the body control module

    Supported by vehicle data
    Why it ranks here
    GM's 04-08-47-003 covers B2958/B2960 on 2000–2005 Impala and Monte Carlo, and an owner quotes its fix as repairing poor terminal connections at the BCM.
    What would change this
    Rises on an Impala or Monte Carlo of those years. Falls if the BCM connections are clean and tight.

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Have the body control module codes read with a scan tool, and note any B2958, B3033 or other security codes stored with B2960.

    Low riskTool: scan tool with body control module access

    • IfB2960 with B2958 on a 2000–2005 Impala or Monte Carlo

      It meansGM's BCM connection bulletin applies.

      Go to step 2

    • IfB2960 with B3033 on a Saturn Ion

      It meansGM's cold-weather no-crank bulletin applies.

      Go to step 2

    • IfB2960 alone

      It meansThe Passlock sensor or its signal is suspect.

      Go to step 2

  2. Give your VIN to a dealer and ask which GM bulletin covers B2960 on your model.

    Low risk

  3. Have a technician run GM's Passlock diagnosis before replacing parts.

    Use cautionTool: scan tool with body control module access

    Warning:Theft-deterrent parts have to be matched to the vehicle with the right procedure; swapping them on a guess can leave the car unable to start.

Symptoms

  • Security or theft light on in the dash
  • Engine cranks but won't start, or won't crank at all
  • Engine stalls (some 1998–2001 GM trucks and vans)

How to fix

Parts and cost context

  • Ignition lock cylinder with Passlock sensor:A technician should confirm it is the fault before replacing it. Labour varies; get a quote.
  • Body control module connectors:GM's Impala/Monte Carlo fix repairs poor terminal connections. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Chevrolet

  • 1999–2001 · Silverado

    Supported by vehicle data

    GM's bulletin covers the security lamp, stall and no start with B2960. Whether it is still current is not verified.

  • 2000–2005 · Impala

    Supported by vehicle data

    GM's bulletin covers B2958/B2960 with a no-crank; owners quote the fix as repairing BCM terminal connections. Whether it is still current is not verified.

  • 01-08-56-002AStatus unverified

    Security lamp, engine stall, no start, B2960

    1999–2001silverado, tahoe, suburban · issued · NHTSA 623100

    Some trucks may show the security lamp, stall and not start with B2960. Also covers GMC Sierra and Yukon.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 01-08-56-006Status unverified

    Security lamp, engine stalls, no start, B2960

    1998–2001g-van · issued · NHTSA 627816

    Full-size G vans with the security lamp, stall and no start with B2960.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 04-08-47-003Status unverified

    Security light on, engine will not crank, B2958 and/or B2960

    2000–2005impala, monte-carlo · issued · NHTSA 10011075

    Security light and no crank with B2958 and/or B2960.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Saturn

  • 2003–2006 · Ion

    Supported by vehicle data

    GM's bulletin covers a cold-weather no-crank with B2960 and/or B3033. Whether it is still current is not verified.

  • 03-08-56-002Status unverified

    Intermittent security telltale and/or B2960

    2000–2004l-series · issued · NHTSA 10003597

    Intermittent security telltale illumination and/or B2960.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 04-08-45-005Status unverified

    No crank, no start in cold weather, B2960 and/or B3033

    2003–2006ion · issued · NHTSA 10007431

    No crank or no start when it is cold, with B2960 and/or B3033.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Isuzu

No curated relationships for B2960 yet.

All Body electrical codes

B2960 questions

Is it safe to drive with B2960?

If the car starts and runs, get it checked soon. GM's bulletins describe stalls on some 1998–2001 trucks and vans, so stop driving if the engine cuts out.

Sources and review

  1. GM 01-08-56-002A: security lamp on, engine stall, no start, DTC B2960 — General Motors ,
  2. GM 04-08-47-003: security light on, engine will not crank, DTCs B2958 and/or B2960 — General Motors ,
  3. Saturn 04-08-45-005: no crank, no start in cold weather, DTCs B2960 and/or B3033 — General Motors (Saturn) ,
  4. GM 01-08-56-006: security lamp on, engine stalls, no start, DTC B2960 — General Motors ,
  5. GM 200900: diagnosis of Passlock DTC B2960 — General Motors ,
  6. NHTSA complaint ODI 10616171 (2002 Chevrolet Malibu) — NHTSA Office of Defects Investigation
  7. NHTSA complaint ODI 10895501 (2007 Isuzu i-370) — NHTSA Office of Defects Investigation
  8. NHTSA complaint ODI 10503695 (2003 Chevrolet Impala) — NHTSA Office of Defects Investigation
  9. Saturn 03-08-56-002: intermittent security telltale and/or DTC B2960 — General Motors (Saturn) ,
  10. NHTSA complaint ODI 10743526 (2007 Isuzu i-370) — NHTSA Office of Defects Investigation
Last reviewed
Written by
Saurabh K.
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