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but they're solutions if the gauge sometimes works, in my case that gauge doesn't move at all.
Anyway, before dismounting the dashboard, I'd like to check the temp gauge sender, the problem is, and this is the shame part, I don't know where it is.
RAD4Runner's 4R has it in the thermostat housing: https://www.yotatech.com/forums/f199...l#post52391719
but it's not in my 4R. I think, in my case, it's the one inside the red circle (please see pic attached), is that correct?
The pigtail's blue and the wire's yellow with green stripes, like the one the temp gauge receives (see red arrow in the electric schematic attached).
Picked up a 3.4w bulb and hooked it up per the manual and the needle went right to normal and the light lit up. The manual says if results aren't as expected then test the actual gauge but since they are as expected I guess my next step is to pull the sensor, clean it and test it. I was getting a false reading before when I tested the resistance. I made sure I got a good connection and each time it gave me different readings. Usually in the 40-75 ohm range. I'll report back when I get it cleaned and tested and I will clean the threads as well.
The sender on top of T-stat housing is the Coolant Thermo Switch (TSW for ECU), not the temp gage sender. The temp gage sender is the one on your photo...
(THANKS FOR THIS PHOTO! I could not even find sender on mine) Coolant Temp GAGE sender.
Here's the test for the sender. It only have one wire connected to it so needs clean, bare, metal contact with the block.
After that I flushed the cooling system, I replace the thermostat. I put everything back together. I blocked the rear wheels and I jacked up the front wheels to be sure the top of the radiator was the highest part of the c.system. I slowly filled with Toyota red coolant. After 25 minutes with the engine running waiting to purge, the temperature gauge needle went up a quarter. Happy with the progress, but I expected to go a little bit higher. Is that good?
Update:
I think the engine was not warm enough.
After running the engine for other 30 minutes to purge the cooling system, the needle went up a little bit more. It looks good now.
Last edited by SomedayJ; Mar 25, 2018 at 06:07 AM.
Awesome! Thanks for the update. The temp gage normally sits below the halfway point. It's never exact. It just indicates:
1) Cold,
2) 1/3 of the way = Normal op. temp
4) 1/2 of the way = Working harder than usual
5) About 3/4 of the way = Do something about it (turn AC off, slow down if going uphill, turn heater on, check radiator/fan, etc.)
6) Red mark = overheat, stop, check everything.
An electrical sender with digital read-out would be nice.
Feb 28, 2018 | 12:49 AM
