Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSPONTIAC1997GRAND PRIX GTP, 4D SEDANREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 7 (BODY CONTROL MODULE)DIAGNOSIS & REPAIRDTC B2721, PASS-KEY(R) DETECTION CIRCUIT (OUT OF RANGE)DIAGNOSTIC AIDS
1997 Pontiac Grand Prix GTP, 4D Sedan
Diagnostic Aids
1997 Pontiac Grand Prix GTP, 4D SedanSECTION Diagnostic Aids
WARNING: This page is about a different car, the 1997 Buick Regal and 1997 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
- The following conditions may cause an intermittent: Intermittent open or short to ground in circuit No. 1073 (Black/White wire) or No. 1074 (Purple/White wire); poor connections; or dirty or loose ignition lock cylinder key contacts or PASS-KEY(R) II resistor.
- If key resistor pellet is incorrect, there will be no BCM outputs to theft deterrent relay or PCM for about 3 minutes. If a key (even a proper PASS-KEY(R)) is inserted or ignition is turned on again, 3-minute timeout period will reset. If battery is disconnected, timeout period will be reset when battery is reconnected. During this 3-minute period, the SECURITY warning indicator will flash. After the 3-minute period, SECURITY warning indicator will stay on steady, and BCM will enter the theft deterrent auto-learn mode.
- Though it is unlikely, DTC B2721 may set due to extremely hot or cold ambient temperatures. To eliminate this possibility, perform tests with vehicle and key at room temperature.
- Clean key resistor contacts thoroughly. Check for poor connections at BCM and ignition lock cylinder. A poor connection may cause an open, an incorrect PASS-KEY(R) resistance or an intermittent malfunction.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.