Temp Gauge is Not Working...

[clemsontaco]

So my temp gauge has decided to quit working (stuck at the very bottom below cool) and after replacing the three parts that I thought it would be, I am now stuck on what to do next. My check engine light has not come on and therefore making this extremely hard to diagnosis without any codes to give me hints. Any help will be greatly appreciated.

I have an 02' taco with the 3RZ

So far I have replaced:
-ECT Sensor
-Thermostat
-Main O2 Sensor (Bank 1, Sensor 1)

After replacing all of these, the temp gauge is still not working and I am left clueless on what to do next. Anything I am missing? Any advice?

 

[Deleted member 13060]

The gauge stuck a the end of it's travel usually indicates a short to ground, a short to power or a broken wire. I'd suspect the gauge last... I haven't seen too many broken gauges in 20+ years of fixing cars for money...

YMMV RON

PS why did you change the O2 sensor?

 

[clemsontaco]

This is might sound stupid but how would you go about fixing that?

And I replaced the O2 sensor because initially I got a check engine light and the code said faulty O2 sensor...took care of the light but obviously not the temp gauge.

Thanks for the help.

 

[cruiseroutfit]

Have access to a Scangauge or similar. It would be easy to determine if the computer is getting the reading from the engine coolant temp sensor. At least from there you know to work between the ECU and the gauge cluster.

 

[keezer37]

Have access to a Scangauge or similar. It would be easy to determine if the computer is getting the reading from the engine coolant temp sensor. At least from there you know to work between the ECU and the gauge cluster.

And if it's good, check the brown wire.

 

[clemsontaco]

Thank you all for the feedback and sorry for the delayed response...I have been incredibly busy to say the least. So I went Advanced Auto and picked up an Actron Scanner and it gave me a coolant temperature reading (196 Deg) therefore eliminating the sensor. I then removed the instrument cluster and preceded to check a couple of things within the instrument cluster/wiring harness. Sadly, I am just as confused as when I started and thought yall might be able to help me out again. Here is what I have done:

Instrument Cluster:
-Used 1.5 volt battery with negative terminal on temp screw (located on back of temp gauge), positive terminal on ground screw (located on back of temp gauge) and the temp gauge turned all the way hot.

Wiring Harness for Fuel Gauge:
-Measured voltage between ignition and ground and got 12 volts
-Measured voltage between ignition and temp and got 12 volts

Do any of yall have any suggestions as to what might be the problem now?

 

[keezer37]

Did you check the fuse (10A GAUGE)? If it's good, with the fuse out, make sure you have power on one side of it. (Check for power with the ignition switch to the ON position.

Beyond that, your ground point is "EF" on page 42 located on your motor. Though I believe this is a ganged ground and if you've no other issues... I'd check the fuse.

 

[eblau]

Looks like the 3RZ has a temp sender and an ECT like most vehicles. The ECT has nothing to do with the gauge. I'd try grounding the wire from the ECT see if it moves the needle, if it does the coolant temp SENDER would be the culprit.

http://www.ncttora.com/fsm/2003/Wiring_Manual/03tacoma/systemci/052cmtac.pdf

 

[clemsontaco]

-Checked the fuse and it is good (even replaced it with a brand new one).
-I pulled the fuse and ran the multimeter from the fuse (power side) to the ground and got 12 volts.
-Checked my ground point on the motor and cleaned it up a bit.

Still no luck and now my temperature gauge has decided to quit working on me. Any other ideas?

Thanks again.

 

[clemsontaco]

Where would the sender be located?

 

[clemsontaco]

Ok so finally found the problem. After many headaches and trial and errors the solution was as simple as tightening a loose nut.

Finally decided to completely disassemble the instrument cluster and remove the individual gauges. After removing the temp gauge, one of the three nuts was almost completely off. Screwed the sucker back on and what do you know..I now have a temp reading.

Also, took some time to try to calibrate my tachometer. After searching online on how to do this, I found hardly anything that was related to tacomas. So I decided to pull it apart and as it turns out, it is real easy to calibrate. Using the scanner I purchased, I could see the actual digital RPM reading. Using this reading, I could easily adjust the needle by pulling it off and then resetting the needle with the throttle at a given RPM (say 1000 RPMs). Really simple fix.

Thanks again for all the help.