Where is the throttle position sensor located on the 1999 Cadillac DeVille?

The throttle position sensor is serviced as part of the throttle body.
See the image below :----


To replace the TP sensor,follow the procedure as follows :---

Partially drain the coolant system. Loosen the hose clamps to remove the air inlet hoses and the coolant hoses. Disconnect the vacuum hoses from the throttle body. Remove the throttle position (TP) sensor electrical connector.
1. 
   
Remove the throttle body assembly mounting bolts. Remove the TP sensor throttle body assembly.

 

Install the throttle body assembly with the TP sensor. Ensure that the O-rings are properly positioned. The O-rings should seal to the intake plenum. 
1.  
2. 
   
   Notice: Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.
   Install the mounting bolts.
   
   Tighten
   Tighten the mounting bolts to 22 N·m (16 lb ft).
   Install the vacuum hose, the air inlet hose, and the coolant hoses.
   Connect the TP sensor electrical connector.
   Perform the idle learn procedure by turning the key ON for 30 seconds while leaving the engine OFF to resume the normal idle.
   Check the engine coolant level. Refill the coolant if the reading is low.

This details will help.

Thanks.

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