92 SC400, w/ 1UZ-FE.
It seems I have 3 coolant temperature sensors (see pics). From other posts, #1 was identified as the Engine Coolant Temperature (ECT) sensor. This is the one that sends signal to ECU, right? I changed #1 with a new one after the old one broke in half when removing the electrical connector. What about 2 & 3? What are they for?
CRuby

 

3 is the one that goes to the gauge cluster.

 

Bump ......^.......
Anyone know what temperature sensor 2 is used for? View is looking at engine from front, thermostat is just to right in picture.

 

I found this pic of a 95 SC400 & it doesn't even have the #2 coolant sensor.
I'll be leaving it as is for now, but I'd like to know it's use, without chasing the wires. More out of curiosity, since I have bigger issues; ECU hiccups, leaking doors, and replacing my instrument cluster. Sorry, just venting. I've found many of the postings that address these problems & I'm grateful for them. But if you know the use for this #2 sensor, please reply.

 

Should be one for the hydro fan setup, ecu, and gauge cluster, later models did away with the hydrofan one and got the signal from the ecu.

 

I believe #2 is the Start Injector Time Switch

 

^ pretty sure this dude is correct, early 1uz had a cold start injector and early Toyota efi used a second 5v two wire thermistor to switch on said injector.

 

can cold start injector or tinmer fail open? Im getting high HC on a smog test with new plugs, in spec 02 sensors and questionable cats that passed last time.