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.
1991 Pontiac Sunbird Base, 4D Sedan, StandardFACTORY OEM SERVICE PROCEDURE
Electronic Spark Control (ESC) Retard System, With ESC Controller (C-5)
- An open or short circuit on the ESC wire to the ECM will cause a loss of the 12-volt ESC controller signal. This will cause the ECM to fully retard ignition timing.
- If a "Scan" tester is available, connect it to the ALDL connector. Tap on engine next to knock sensor and note "knock" parameter. Knock should be indicated on "Scan" tester.
- If a "Scan" tester is not available, connect a DVOM to the ECM ESC signal terminal. With engine idling, 12 volts should be present at this terminal. Using a metal object, tap on engine close to knock sensor. Voltage signal at ECM terminal should drop to zero volts, and return when knock signal ceases.
- If signal does not respond as described, check knock sensor signal to ESC controller. On vehicles equipped with automatic transmission, it may be necessary to place transmission in Drive for timing change to occur. Also, see KNOCK SENSOR under ENGINE SENSORS & SWITCHES in this article.
Factory Service Tools
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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.
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