Tachometer reading low

[machine_51]

After missing my 97 I finally got back into another T4R. This last week I picked up a '04 SR5 V6 with 84k miles on it. The truck is in amazing shape, loving it right now. The other day when I was driving home I noticed that my tach was reading 0 at the stop sign. It will rise when I step on the gas and drop when I let off. When I put it in neutral it would be sitting around 300 rpm and then drop to 0 when I put it back in gear. Has anyone seen this? The engine is smooth and everything is working like it should. Just hoping this isn't a early sign of something big.

 

[DC runner]

At 0, that engine would be sputtering to all heck.
So, is the engine running smooth the entire time? If so, its the sensor or wire.

 

[cabowally]

The FSM has very specific instructions as to how to diagnose this issue.

It's either the cluster, harness, connector or ECM.

You need an oscilloscope to test it.









..

 

[machine_51]

The engine runs as smooth as my ex's 06 Tacoma's 4.0L. There is no hesitation, or flat spots in the rpm so I believe it to be in the gage. The rpm's are reading 1300 at 60 mph too. Not sure if that I what a typical 04 V6 will run. I was wondering if that was a normal for the 4-speed.

I'll check the FSM this weekend and see what I find out. Thanks.

 

[machine_51]

The FSM has very specific instructions as to how to diagnose this issue.

..

Do you know where in the FSM it tells this. I looked in an 03 FSM and did not see anything. Do you have a page number that I can reference, maybe I'm in the wrong part since it is in 100 different .pdf files.

 

[Exploresystems]

Interesting...I have an 04 V6. The tach will fluctuate up and down when on a road trip. I believe mine is in he gauge too, everything else seems to function properly. Interested in the out come.

 

[cabowally]

Running out and don't have time to sift through the FSM. Pulled this info from alldatadiy for a 2007 V8. Should be the same, I think.


Tachometer Malfunction


Tachometer Malfunction

DESCRIPTION

When turn the ignition switch to the ON position, the combination meter assembly communicates with the ECM by the direct line.


GOOD LUCK!

 

[machine_51]

Awesome! I'll try this and see what I can come up with and hopefully post something soon. Thanks for all the help!

 

[machine_51]

So I dug out an old scope from my work and hooked it up. I get the squarewave form that I'm supposed to get so it tells me to replace the combination meter assembly. But then I tested the wiring harness/connectors for continuity and there is none, which there should be. So now I'm not sure if I just cannot get a good connection with my leads to show continuity. Thanks again for all the help cabowally.

 

[20034RunnerV84x2]

Check the fuse for the gauges under your left foot. Maybe its in the wiring under there? Possibly a loose wire that sometimes gets power and sometimes doesn't?