Whats up with my Tachometer

[krs09]

Im trying to figure out whats going on with my tachometer? When I turn on my car the needle moves a little but sits a 3 (3,000 rpms), when I rev the engine the needle doesnt budge, not a bit. It hasnt worked since I bought it. Every once in a while when I turn the key to "on" the needle may drop to around 0 (where it should be) but as soon as I fire the engin up it goes right to 3,000 rpms and sits there and I know my idle is much lower than that. I did replace my RPM relay with an updated one from DMCH but it made no difference. Not sure where to go. I seen the connector for the dash panel all the way up, right under the binnacle. Any "go to" ideas to check? Figured Id check with you guys before I go crazy. Thanks

[Elvis]

Strange - why do you think it has to do with the rpm relay ? LOL


Replace the chip on the PCB of the tacho and you're good.
They fail rarely.

[Bitsyncmaster]

The tach RPM signal comes from the coil output of the ignition ECU. So if you have a non-stock coil or non-stock ignition ECU that may be the problem. Most likely your tach is bad or the signal to the tach may be broken. The connectors to the tach and all the gauges are prone to getting messed up when someone removes the binnacle. Yes the RPM relay also uses that signal but it's rare it could cause the problem with the tach.

[Ryan King]

Mine did something similar on one of the many times I pulled my Binnacle. If any of these little copper pins get pinched, it gives the gauges wrong readings, makes things not work, etc.
20851

[sdg3205]

When I was restoring 2510 (with 2,100 miles), only two, count that... TWO items (in this case lights) in the cluster worked. I had to clean all the contacts as many as five times before the oxidation had been removed sufficiently to restore function. Moreover, i had a bad temp gauge, which i tested to confirm. Moral of the story is clean the hell out of the connectors and trouble shoot the gauge because they DO stop working.

[aipri]

I just noticed this same issue today. The tach worked fine when I drove the car two days ago. Today it's stuck at 2500 RPM and won't budge.