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.
1993 Cadillac Eldorado V8-300 4.9LFACTORY OEM SERVICE PROCEDURE
Transmission Position Sensor/Switch: Description and Operation
PRNDL-P/N Switch:
PCM Wiring:
The PRNDL switch is part of the transmission Neutral Safety-Back Up (NSBU) Switch, located on the top of the transaxle. The PRNDL switch provides four inputs to the PCM to indicate the transmission gear position. Gear position information is used by the PCM to control shift solenoids and TCC operation. Improper switch operation will cause PCM code P091 to set.
Factory Service Tools
Use the Manual With the Right Hardware
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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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