Coolant Sensor for 3VZ-FE

[rusty9]

first of all i'd like to say the cooling system for this engine was designed by a jackass.

now, i suspect my cooling fan isnt kicking up to high speed when it should. i checked the solenoid on the pump and its within spec when cold ~8 Ohms when cold, no information on what its supposed to be when hot. cooling fan ECU is within spec based on the limited chart for checking it. and the fan speed does raise slighly when i jump E1 and OP1 on the diagnostic port, so i believe the ecu to be functioning correctly.

UPDATE: I'm making a hydraulic fuck you fan diagnostic checklist for everyone once i complete working on this

[rusty9]

alright after double checking the harness at the cooling fan ECU i noticed that pin 5 to ground(TPS signal) has continuity at idle(normal), lost continuity at throttle open(normal) but did not return to continuity after releasing throttle to closed.

with the multimeter still connected to the harness connector, i loosened the TPS sensor and rotated it until the meter showed the lowest resistance and re-tightened it.

as to the previous post about the sensor, i am reluctant to say it may not be at fault. with the cooling fan ECU unplugged, and ignition on, readings at the sensor itself and at the ECU connector seem to be normal. only when its plugged in do i get strange numbers at the sensor.

i dont know, maybe the ECU is defective in some way. its getting proper voltage from the engine ECU connector E8 between pins 4 THW and 9 GND(which comes from the second temp sensor on the water outlet, which is functioning correctly), but voltage across pins 9-10 on cooling ECU seems a little off right now. i have to test that again when its completely cool, and fully hot.

i'll update again after i drive around some more with the TPS adjustment.

i also got another part number for a water sensor, 89429-33010 which i believe may be the correct sensor for the cooling ECU. its $85 bucks tho, so i wont replace it if mine is within spec.

UPDATE: ok so im leaning towards faulty cooling ECU because voltage between pins 9-10 is at a little over 3v when the engine is almost cold. spec says 2.5v at 68 degrees and 1.2v at 176 degrees(normal warm range). since the ambient air temp is over 90 today the voltage should be 2v-2.5v. now i have to check the voltage when its warmed up again.

[rusty9]

well after trying 2 different cooling ecu's from the junkyard this morning i still get the same voltage results. im running out of things to check. last thing would be to see if the fan motor is getting proper fluid pressure, but i dont have the tools to check that =/

im about to give up and buy an electric fan system. or somehow retrofit the fans i have from my old 5s

[73sport]

I've got a liquid filled high pressure gauge but we'd be shipping from border to border acorss the US.

Your pump has two chambers so I suppose one could go bad but it'd fill the system with metal. Have you changed the fluid and done a good flush? Fresh ATF is highly detergent and could free up sluggish and sticking valves.

IF you jumper the cooling ECU's can you get full speed operation?