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.
Diagnostic Procedures
1999 Buick Regal LSSECTION Diagnostic Procedures
- Perform On-Board Diagnostic (OBD) system check. See ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK under SELF-DIAGNOSTIC SYSTEM in SELF-DIAGNOSTICS INTRODUCTION article. After performing OBD system check, go to next step.
- Start and operate engine at idle. Using scan tool, select MISFIRE DATA LIST and monitor IC No. 2 status. If scan tool displays DTC P0352, go to step 4. If scan tool does not display this DTC, go to next step.
- Turn ignition on, with engine off. Using scan tool, review FREEZE FRAME and/or FAILURE RECORDS data and note parameters. Turn ignition off for about 15 seconds. Start engine and operate vehicle within conditions required for this diagnostic to run, and as close to conditions recorded in FREEZE FRAME/FAILURE RECORDS as possible. Select DTC function, then enter DTC P0352. If scan tool indicates that this test failed this ignition, go to next step. If scan tool does not indicate that this test failed this ignition, see DIAGNOSTIC AIDS .
- Turn ignition off. Disconnect ignition coil No. 2 connector. Using a DVOM in AC Hertz (Hz) scale, check frequency of IC No. 2 signal circuit. Start and operate engine at idle. If frequency is 3-20 Hz, go to step 8. If frequency is not as specified, go to next step.
- Using DVOM, check voltage on IC No. 2 signal circuit. If voltage reading is greater than one volt, go to step 9. If voltage reading is not greater than one volt, go to next step.
- Turn ignition off. Disconnect PCM harness connector. Using DVOM, check continuity of IC signal circuit from ignition coil No. 2 connector to PCM connector. If continuity exists, go to next step. If continuity does not exist, go to step 10.
- Using DVOM, check resistance of IC signal between ground and ignition coil No. 2 connector. If resistance is infinite, go to step 11. If resistance is not infinite, go to step 10.
- Replace ignition coil. After replacing coil, go to step 13.
- Repair IC signal circuit for short to voltage. After repairs, go to step 13.
- Repair IC signal circuit for open or short to ground. After repairs, go to step 13.
- Check for poor connections/terminal tension at PCM connector. Repair as necessary. After repairs, go to step 13. If connection or terminal tension is okay, go to next step.
- Replace PCM. Program replacement PCM using required equipment. After replacing PCM, go to next step.
- Using scan tool, select DTC, CLEAR INFO function. Start and warm engine to normal operating temperature. Select DTC, SPECIFIC, then enter DTC P0352. Operate vehicle within conditions for setting this DTC. If scan tool indicates that this test ran and passed, go to next step. If scan tool does not indicate that this test ran and passed, repeat step 2.
- Using scan tool, select CAPTURE INFO, REVIEW INFO function. If any undiagnosed DTCs are displayed, go to applicable DTC test.
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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.