Where is the "Throttle Position Sensor" located at on the engine?

Your 2000 Frontier only has the one TPS sensor.

P1296 CHRYSLER - 5 Volt Reference Voltage Missing At Throttle Position Sensor
https://www.autocodes.com/p1296_chrysler.html

I found this picture, if that is correct? Probably a three wire connector, ref voltage--ground--signal. I did see another picture, I wasn't sure? This picture said dfi.

Look at the air intake to the throttle body on the intake manifold. With the engine shut off, have someone operate the throttle. Look for the moving butterfly and follow it to the position sensor.

For location of throttle position sensor and its replacement procedure,Click the link below and go through the diagram and procedure :----http://schematicsdiagram.blogspot.in/2012/02/where-is-throttle-position-sensor.html
-----------This will help.Thanks.

All TPS Sensors have to be on the throttle body

Throttle Position Sensor (TPS) !!

DTC P1120 - Boost Pressure / Throttle Position Sensor Malfunction
Hope this helps. God Bless

the censor is located adjacent to the throttle control linkage, and has a 3 wire connection plug

The throttle position sensor is located between the air filter box and the intake manifold. If you aren't familiar with engines, the air filter box is usually located behind the driver's side headlight. There is a rubber tunnel that runs from the air box to the intake manifold. Between the rubber tunnel and the intake manifold you will find the throttle bolted to the intake manifold. The sensor is located on the throttle.

How to Replace a Throttle Position Sensor
(DIY & Save up to $135.75 ) - Time: 2.1 hours

Parts:
1. Throttle Position Sensor - $ 55.44

Tools:
1. Scan Tool
2. Screwdriver
3. Multimeter

Procedure:
1. Locate the OBD data link connector (DLC). Refer to your owner’s manual for the specific location.

• Tip: The OBD-I data link connector is usually located in the engine compartment near the battery or the fuse box. The OBD-II connector (post 1995 cars) is usually located beneath the instument panel next to the steering column.

2. Turn your key to the“ON” position. Do not start the engine.

3. Plug your scan tool into the OBD data link connector. Turn on the scan tool and select the appropriate steps to read the diagnostic trouble code (DTC).

Scanner plugged into OBD-II data link connector.

• Tip: The OBD-II diagnostic trouble code (DTC) is a 5 character alphanumeric code. The first digit is a letter that indicates the component group, the second digit is OBD mandated or manufacturer specfic, the third digit is a subgroup, and the fourth and fifth digits define the component and basic problem.
  

• 4. Locate the throttle position sensor.

• 
  
• Throttle position sensor
  

• 5. Disconnect the electrical connector from the throttle position sensor.

• 
  
• Electrical connector removed
  

6. Test the resistance of the throttle position sensor (TPS) with a digital multi-meter. If the resistance is out of specifications, the TPS must be replaced.

• 7. Remove the throttle position sensor.



Removing sensor mounting screws

8. Install the new throttle position sensor. Tighten the mounting screws and attach the electrical connector.

• 9. Erase the diagnostic trouble code (DTC) with the scan tool using the“delete” or“erase” command. Road test your vehicle to see if the check engine light returns.

Check engine light


• Tip: If the check engine light returns, repeat the diagnostic process for additional DTCs or take your vehicle to a certified repair shop.

Direct OE replacement

Hope helped with this. Good luck (remember rated this help).