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 MANUALSCADILLAC1991SEVILLE V8-300 4.9LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSTHROTTLE POSITION SENSORADJUSTMENTS
1991 Cadillac Seville V8-300 4.9L
Throttle Position Sensor: Adjustments
1991 Cadillac Seville V8-300 4.9LSECTION Adjustments
With the engine running, select PCM/ECM override ES03, and press the cooler button . select PCM/ECM data ED01, and if it reads -1.0° to +1.0° adjust the ISC solenoid. If the parameter reads -10.0° to -1.1° or +1.1° to 90.0° adjust the TPS as follows:
1. Using a torx driver T-25, loosen the TPS screws just enough to permit the sensor to be rotated.
2. Open the throttle and allow the throttle lever to snap shut against the minimum air screw.
3. Adjust the TPS so the parameter display is -.5° to +.5°.
4. Tighten the TPS mounting screws with the sensor in the adjusted position.
5. Recheck the parameter to be sure the TPS parameter is -.5° to +.5°.
1. Using a torx driver T-25, loosen the TPS screws just enough to permit the sensor to be rotated.
2. Open the throttle and allow the throttle lever to snap shut against the minimum air screw.
3. Adjust the TPS so the parameter display is -.5° to +.5°.
4. Tighten the TPS mounting screws with the sensor in the adjusted position.
5. Recheck the parameter to be sure the TPS parameter is -.5° to +.5°.
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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.