Coolest temp sensor for gauges

2004 Tacoma with the 3.4. Trying to find the single wire temp sensor for the coolant temp gauge. Gauge reads above the H on start up when motor is cold. Dealer claims to have replaced it and the gauge when I bought it used a couple months back. It had the same issue, that’s why those parts were replaced. Worked fine for a couple months, now acting up again. I’d like to find it so I can test it myself before I take it back. Only thing I found was through Haynes, the diagram looks like a kid in pre-K drew it. Points somewhere on the driver side rear of the motor? Any ideas?

 

The coolant temperature SENDER is the one that outputs to the dash gauge. The coolant temperature SENSOR outputs to the ECM.

On most vehicles the SENDER is located at the coolant output hose going into the radiator. I believe this is where it is on the 5VZ, it is definitely in that location on the 3RZ.

 

The sender should still only have one wire going to it right? Since I’m not getting a trouble code, the sensor should be good. I’ve located what I suspect to be the sensor near the upper hose inlet. It has two wires going to it.

 

So what you’re saying is that the dealer just started replacing parts that didn’t turn out to be the actual problem?

You don’t say...

 

Yeah, shocking. Found the sender, took me some time.
Just in case anyone else needs to know, it’s on the backside of the intake manifold near the center of the firewall. Single wire connector. It’s hidden under a hose; like a heater hose I suspect.

 

Could be a bad ground at the gauge.
If you ground the wire at the engine temp sender the temp gauge should go to hot. (Only do this briefly or it could ruin the gauge)
Test the coolant temp with an infrared sensor by pointing it at various places, (radiator, thermostat housing) so you know what true normal is.