4.0 V6 Coolant Tempurature Sensor Location and How to Change

[Supersonic]

Took me forever to find it, middle rear just in front of a heater hose and right side fuel rail hampers getting a hold of connector to remove it. Anyhow, not sure why the instructions for this is so little, maybe I am just not a good enough sleuth.

Cold motor.
Drain some coolant about 3/4 to one gallon,
radiator drain is at bottom left, open till small amount drips, remove cap, adjust as necessary.
so you don't have it leaking all over when replacing temp sensor.
Remove air filter and
next intake air housing up to throttle body, including throttle body clamp,
the 2 10mm screws,
the connector to Mass Air Flow Sensor, and
1 vacuum line at rear of housing.

then 3 bolts for the passenger side fuel rail, real tight, (not sure of the torque, I just tightened approximately as tight as I thought when they came off without stripping, but they are tight).
no I didn't disconnect the fuel line or relieve the pressure,
just lifted the fuel rail up high and forward enough to get my hand in to disconnect the sensor, you'd better have fairly small hands or your results may very and you will need to do more.
And yes, all three injectors are lifted as is within the rail for the duration, be careful!
Or if you could figure out how to disconnect the sensor connector and get it off with pliers, screwdriver, ect, then you could get around lifting the fuel rail forward.
Squeeze hand into the tight space to disconnect temp sensor.

Then its easy
19mm socket removes old sensor,
install new sensor,
connect the plug,
3 bolts to fuel rail, be careful placing injectors correctly
install air housing not forgetting the vacuum line at rear
before connecting the electrical connection--clean Mass Air Flow sensor that is located at front top of housing, 2 Phillips screws (remove, spray up into to clean the 2 resistors inside the bottom, the little bulb is air temp I think, but be sure you know where the resistors are and get them cleaned too).
reinstall and connect Mass Air Flow,
button up the air filter.

Here's the only reference I found prior to changing it out; | Repair Guides | Coolant Temperature Sensor | Removal & Installation | AutoZone.com Although I found some other instructions I'll link to that later if I can find it, probably from the Tacoma forums.

I also might have disconnected a tie-down(plastic rivet or whatever they call it) for wire harness nearby, but it seems this may or may not be necessary.

 

[USS_Johnston]

Ok, sorry If I cause confusion here but I am new to message boards and do not know how to begin, nor can I locate a tutorial so, here goes.

Similar to the above post, I also have had an erratic gauge reading. When connected to a Bluetooth to phone scanner (OBDLinkMX) I can monitor the engine ECM reported temperature at 210. The gauge, however; moves up like normal(ish). After what was long distances and now only short distances, it climbs toward the red and beyond. If I shut it down and wait, the gauge will fall back into the normal zone, quickly. Since the scanner can read both it tracked the gauge going from 240 (apparently max) to 200 in about thirty minutes while tracking the ECM sender to have gone down maybe three degrees. Since physics basically prohibits the engine to drop that fast, when shut off an not under water or in antarctica (I am in central Florida) I am assuming that the sender for the gauge is defective. Now, I have trawled this forum and downloaded the various service manuals on offer as well as reading posts in regards to 4thgen 4.0L and I can not find anything specific to this. Nor can I find, in any of the books or online, where the bloody sender is located. I have purchased a new one and every search points to the engine ECM, which I have found on the engine and will replace once I find this little bugger. Does anyone have any idea where this sender may be located? For reference, I purchase both a Napa TS6677 and TS6678. The TS6677 is for the ECM and again, can see it. The TS6678 is, who knows. Anyone else have this problem or think I am barking up the wrong tree?