tach

dglad

Registered User
My tach will sometimes work but most times not is there anything i should check i pulled the dash apart and didint find anything loose there.
 
I have the same problem, some times it works, but some times it points straight up. And it will switch between working and not working it seems for no reason. I’ve tried cleaning the connections at the DIS but that didn’t work.
 
I third this haha. I even installed an aftermarket tach and it still does it which leads me to believe something is up with the DIS. I thought about buying a new one and trying it out but havent gotten around to it. Mine seems to only do it when the car gets warmed up good and the underhood temp is hot. I dont know if maybe something happens when the DIS gets warm maybe something goes faulty in it. Do u notice yours going out when it gets warm also? just something i am trying to check.

Matt
 
I think sometimes the cam sensor or the tach itself can go bad but not sure. Plus if you are running an aftermarket tach MSD makes an adapter to make it work. Although I have heard on here where some people with the MSD tach adapter have said the tach needle will bounce around a little at idle.

Shane
 
I'm not certain about this, but here goes. The tach is driven by the IDM signal from the DIS. If you have any IDM error codes (18, 212, 218, 222, 224, 226, or 241) then that will point to a problem with the DIS.
 
My 35th has been doing that for 2 years. It's very intermittent and getting worse. I've tried 3 tachs, 2 cam sensors, soldered the tach connections to the backplane, and run a jumper wire to another tach signal point with no results. It doesn't seem to affect the car at all. It looks just like a bad connection that making and breaking. I've been suspecting a connector but haven't found it yet. I've thought about the DIS. I'll swap it out tomorrow.
 
J.D. said:
I'm not certain about this, but here goes. The tach is driven by the IDM signal from the DIS. If you have any IDM error codes (18, 212, 218, 222, 224, 226, or 241) then that will point to a problem with the DIS.
i dont have any DIS or IDM codes. i do have another DIS laying around, is there any harm in swapping DIS' back and forth to trouble shoot it?
 
I don't know if it is possible for a bad tach (input is shorted to ground or to 12v) to do damage to the IDM output of the DIS. In your case I wouldn't be so concerned as your tach does work, albeit intermittently. I would make sure to use heat sink compound on the replacement DIS.
 
I bought a brand new dis and installed it and my tach didnt work but now for the last couple of days its been working so i dont know whats up.
 
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