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 B2739, KEY-IN-IGNITION FAULTTESTING
1997 Pontiac Grand Prix GTP, 4D Sedan
DTC B2739, Key-In-Ignition Fault: Testing
1997 Pontiac Grand Prix GTP, 4D SedanSECTION Testing
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.
- If BCM diagnostic system check was performed, go to next step. If BCM diagnostic system check was not performed, go to BCM DIAGNOSTIC SYSTEM CHECK .
- Turn ignition off. Disconnect BCM 32-pin connector C1. Turn ignition on. Using test light, backprobe between ground and BCM harness connector C1 terminal D1 (Light Green wire). If test light illuminates, go to next step. If test light does not illuminate, go to step 4).
- Leave test light connected as indicated in step 2). Turn ignition off. Disconnect ignition key alarm switch (part of ignition key cylinder). If test light illuminates, go to step 5). If test light does not illuminate, go to step 6).
- Using test light, backprobe between battery voltage and BCM harness connector C1 terminal D1 (Light Green wire). If test light illuminates, go to step 7). If test light does not illuminate, go to step 8).
- Repair short to voltage in Light Green wire between BCM connector C1 and ignition key alarm switch. Go to step 12).
- Replace ignition key alarm switch. Go to step 12).
- Turn ignition off. Reinstall all components and connectors. Turn ignition on. Clear DTCs. Check for DTCs. If DTC B2739 sets again, go to step 13). If DTC B2739 does not set again, system is operating properly.
- Using test light, backprobe between battery voltage and 48-pin connector C201 terminal B3 (Light Green wire). Connector C201 is in instrument panel-to-steering column wiring harness, located on right side of steering column. If test light illuminates, go to next step. If test light does not illuminate, go to step 10).
- Repair poor connection or open in Light Green wire between BCM connector C1 and connector C201. Go to step 12).
- Using test light, backprobe between battery voltage and 48-pin connector C201 terminal B4 (Black wire). If test light illuminates, go tostep 6). If test light does not illuminate, go to next step.
- Repair poor connection or open in Black wire between connector C201 and ground. Go to next step.
- Turn ignition off. Reinstall all components and connectors. Turn ignition on. Using scan tool, clear DTCs. Perform BCM DIAGNOSTIC SYSTEM CHECK .
- Turn ignition off. Replace BCM. See REMOVAL & INSTALLATION . Reprogram BCM. See BCM PROGRAMMING. Go to next step.
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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.