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
Converter Lock-Up Signal From ECM
- Warm engine to operating temperature. Raise vehicle and support drive wheels. Support suspension where necessary to prevent damage to drive axles.
- Connect a test light to battery voltage. Touch TCC control driver terminal with test light. On some vehicles this is terminal "F" of the ALDL connector. See Fig 1 -Fig 21 . Accelerate vehicle to 45 MPH and note test light. If test light does not illuminate, problem is a faulty ECM connector or ECM
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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