ricky69

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

GS400V8

iTrader: (4)

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.

ricky69

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

ricky69

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