The temperture meter on the instrument panel is not working, on reading. I need to find out which temperture sensor and where it is located. The car is a 1992 Toyota, Previa.

Three things. If it is only the speedo, it can be either the dash unit (unlikely) the wiring between the instrument cluster and the speed pickup sensor, or the sensor itself. The sensor is usually located on the gearbox near the final drive shaft. If you can find it, check it with an ohm meter, it should have a resistance of around 90 ohms, but any reading less than infinity (within reason) usually indicates a good sensor.
If other instruments also don't function, check for a fuse.

Very likely you have an internal problem in the instrument panel itself.

More info needed. Is this a hatch back, sedan, or CRX? Is the odometer mechanical [old style] or digital [LCD numbers] The vehicle speed sensor [located behind the speedometer in the instrument cluster] drives both the speedometer and the odometer [mileage meter]. It sounds like an electric problem in the instrument cluster. Remove the instrument cluster and take it to your local speedometer repair shop. Look in the yellow pages for them. Or simply buy and install a used instrument cluster from a junk yard.

You need a new intake air temperture sensor/ mass air flow meter. Located in the intake tube connected to the air filter goin to the throttle body

Possible fault in the sensor/thermocouple or the temperature controller unit.
Locate and use some heat on the sensor to check if this works , if not it this must be changed.

in front .....near hood latch/radiator

most likely you ran into a curb while parking and riped off the temp sensor in the front splash panel. Take it to the dealership to get the correct wire repair and sensor replacement.

This can be your Body Computer Mod. It is located on the right side under your dash. Usually black or gray box about 6'x6'x1' with the plugs. You can by new, but used are fine too. You will need your VIN # for either. Good luck

Check The Vehicle Speed Sensors.

The Legacy has 2 Vehicle Speed Sensors (VSS): VSS1 is located inside of the transaxle; VSS2 is located in the combination meter assembly.

VSS1

1. Disconnect the electrical harness from the transaxle.
2. Connect an ohmmeter across the transaxle's electrical harness terminals 9 and 16.
3. The resistance should be 450-650 ohms.
4. After testing, reconnect the electrical harness.

VSS2

1. Remove the instrument cluster from the instrument panel.
2. Disconnect the electrical connectors and the speedometer cable from the instrument cluster.
3. Connect an ohmmeter or continuity tester across the combination meter terminals 7 and 11.
4. Insert a small screwdriver in the speedometer cable drive socket.
5. Rotate the speedometer drive and note the continuity across the VSS terminal. Continuity should turn ON/OFF 4 times per speedometer drive revolution.

it is located on the cylinder head in between the two front spark plugs