Hello. I would like someone to tell me where the engine coolant sensor is located on a 1999 4Runner with a 3RZ. I know where the one is for the temp gauge, but I don't think that is the same as the ECT sensor. I could be wrong. Maybe they are the same, but it's only a 1 wire and according to my crappy manual, it should be a 2 wire, but that could be wrong also. I know for a fact my temp gauge is not working right. It takes about 15 minutes to even come up. That might be the gauge itself. I really am not sure. I grounded the 1 wire sensor that I did find, and the gauge pegged so maybe it's working. TIA.
ECT sensor location
- Thread starter 4SKIN
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thecole1098
New member
There is 2 separate sensors. The one with the single wire is just a ground and that sensor is solely responsible for the gauge on the dash. The other sensor with 2 wires is the ECT sensor which is responsible for communicating with the ECU. If your only issue is the gauge not working, then the issue lies with the sensor with 1 wire.
Great, thanks for that, but I think I may have two issues going on. When the engine is cold, it has no power and it acts like the timing is off, or it's not getting the proper fuel ratio. After it warms up, it runs great. It's not throwing a ECT code, but I was told that if this motor ever got hot, which it did, it may have damaged the ECT and possibly the gauge sender also. Not enough to throw an ECT code,but still cause this symptom. I'm going to change the gauge sender anyway so as long as I'm in there, I may as well do it too. Just can't find it. Is it on the head, or on the block somewhere?
thecole1098
New member
It should be located on the back of the head. Green connection to it.