Ok, after a week or so of gathering information from half a dozen sources, I wanted to put together a checklist for you guys who may be having troubles with the hydraulic cooling fan on this motor.
You wont need many tools, a screwdriver, 10mm socket and a multimeter. Before you start, be sure your power steering fluid is full and the fan is actually moving relatively slow at idle. One quick check involves placing a jumper wire between pins E1 and OP1 in the diagnostic port. This should increase the fan speed slightly, and you should see power steering fluid squirting up in the reservoir without any air bubbles or foaming which would indicate a leak somewhere.
Most of the checks will be done from the harness behind the glove box so that's where we will start.
1. Glove box removal -
-Start by removing the lower kick panel which is secured by a 10mm nut and push-in pins.
-Remove black instrument panel under cover. It is secured with push in clips
-Remove lower instrument panel. It is secured with 2 screws on either side and more push in clips
-Remove glove box door. Secured with 3 10mm nuts under the hinge. You may need to wiggle the guides on either side to remove them from the box itself.
-Remove the box itself. Its held in by 4 screws. 2 on either side on the bottom, and two in the middle on top. May require some more wiggling.
-The cooling fan ECU is mounted to the same place the door hinge is bolted to.
2. Testing Components. From the harness connector we can test the water temperature sensor(located on the thermostat housing on the left side of the motor) without burning your arms, the solenoid valve on the power steering pump without crawling on the ground, throttle position sensor input, air conditioning high pressure switch, and proper signal voltage from the engine control computer.
Unplug the connector from the ECU. the pin order is reversed in this picture, so verify pin numbers by wire colors
-We will start by testing component specs with the ignition to "On" but engine off
-Water Temp Sensor. Using the multimeter, insert probes into pins 9(blue with white) and 10(blue with yellow) on the connector. I measured 3k-4k ohms while cool. The repair manual states 1.5k ohms at 176 degrees and 0.7k ohms at 230 degrees.
If your measurements are out of spec replace this sensor. there are 2 parts for this, one for cars build before 7/93 and one for after. I have the later model which looks like
this. I found a replacement from car parts wholesale "OES Genuine #W0133-1738143". I do not have the toyota part number for this or the earlier model yet.
Replacing this sensor is relatively easy if you first remove the thermostat housing its attached to, by removing the alternator belt, removing the 3 10mm nuts holding the housing to the block, and one 12mm bolt that secures the pipe right under the alternator hold down bolt. Do this while the engine is cool, and you have a drain pan underneath because a lot of coolant will fall out.
-Solenoid Valve. Using the multimeter across pins 2(yellow with blue) and 3(yellow). Spec is 7.6-8.0 ohms cold. No info if this changes when hot, but mine measured 8.3 cold and 9.0 hot. If you have no continuity, you'll have to crawl under and check to see that the connector is actually plugged in.
-Throttle position sensor input. This is checked by connecting the multimeter to pin 5(blue) to pin 4(brown, ground). you should have continuity or very low resistance with the throttle closed. Lean over and depress the gas pedal, you should lose continuity and regain it when you release the pedal. If you do not regain continuity after releasing the pedal, you will have to adjust the throttle position sensor.
-Engine Control Module Signal. Refer to the diagram below to check this signal.
THW wire is green and E2 is brown. I measured 1.5v while cool and 0.4v when hot. As far as i know, this signal is based on the input from the other coolant sensor known as the
EFI Coolant Temp Sensor. This sensor is located in the middle on the water outlet pipe on the right side of the engine. It has a green connector with a brown wire and a green wire going to it. Check this using the multimeter again and compare to this:
My measurements were 1.1k ohms cool and 0.24k ohms when hot
-Voltage to Water Temp Sensor. For this test we must plug the connector back into Cooling Fan ECU. Insert the probes from the multimeter into where the Water Temp Sensor wires(9-blue with white and 10-blue with yellow) enter the back of the connector. This time measuring voltage. Spec is 2.5v when cool (68 degrees) and 1.2v when hot (176 degrees).
I measured 3.15v when cold and 1.75v when hot. I believe mine may be faulty and will update this when i replace it.
Part numbers:
89422-35010 EFI Coolant Temp Sensor for late '93
89422-20010 EFI Coolant Temp Sensor for early '93 and earlier?
89429-33010 Water Temp Sensor for Cooling Fan ECU?
89257‑33020 Cooling fan ECU
If anyone else has any more info or experience i would be glad to include it!
Hydraulic Fan Diagnostic Checklist (3vz-fe)
** Flush Yearly **
Should help those of you blessed w/hydraulic cooling fans.
Rusty
Linear Mode
