no power to coolant temp sensor
 

hello, i have a 99 gs 300 and my coolant temp guage in the car is inop, i changed the sensor, still nothing, i have a ground at the sensor connection but no 5 volt ref, any ideas?? ( possible ecm ??) by the way where is the ecm located at ?? Thanks for any help in advance

Coolant temp sensors are measured in ohms and not voltage, and no voltage is supplied to it. It is kindof like a photoresistor, but instead of light, it changes with heat. It is kindof like a thermostat, so asit gets warm, resistance goes down, changing parameters of the ECU which it is in parallel with in our ECUs. Measure it when cold (~2500 ohms), and when hot (~350ohms) then you will know if it is working or not.

Same applies to AITs or air intake temperature sensors.

Hey, thank you for your information, i will check it report back to you, Thanks again

just to be sure, the coolant gauge sensor is located under the number 1 injector right ?