Help! C4 Tach not working

[dorock]

I have a 1984 Vette and the tach has quit working. The cluster still lights up as do the numbers but once started, it simply moves back to "00" and stays there. It came back on and worked again for a while but now doesn't anymore.

It would seem to me to be some type of lose connection or something not making contact but I do not know where to find and trace the tachometer wiring or where the contact points would be located.

Hopefully that is an easy question that you can help me with. By the way this is a cross fire injection model if that makes any difference.

Thanks,
Don

 

[G Winter]

The tach is connected to the dist cap on the drivers side. The terminal is marked tach. It should be a white wire. There may also be a tach filter ( cyl, about 1 1/4 in long 5/8 diam) attached with one of the bell housing bolts. there is a connection to that hidden back there. Fun to see what is in that mess.

Glenn

 

[vetteoz]

Corvette Forum - View Single Post - Tachometer Filter Replacement - 1990 Vert

 

[dorock]

I will try to locate it tomorrow and based on the information provided, see if I can get it back working. I will let you know how it goes.

Thanks again for the quick responses.

 

[G Winter]

I wasn't paying attention to the yr. The 84 has a digital tach.
Everything may be diff on those verses an analog tach.

Glenn

 

[vetteoz]

I wasn't paying attention to the yr. The 84 has a digital tach.
Everything may be diff on those verses an analog tach.

If '84 the same as L98 ;same setup .
White wire off dist to tach filter on bellhousing bolt

 

[dorock]

I have already removed it and ordered a replacement tach filter. Hoping that this fixes it.
Thanks,
Don

 

[dorock]

I installed another tach filter but the tach still does not function. It reads 27 when you start it and then goes to double zero's. Where does the white wire going down from the tach mount on the distributor go to? Is there something on that end that I may need to check?

 

[G Winter]

On my 90 the white wire from the tach connection on the dist cap goes to the tach filter , from there to the tach.
There are some links in threads about tachs not working here. Some of them are pretty long and go into great detail . Some are on F body sites.
Glenn

 

[CorvetteArchives]

Thanks to MrBill...again! His wiring diagrams for 84
misterbill.homeip.net - /vette/wiring/

 

[dorock]

How do I get to the back of the instrument cluster to see if the tach wire is properly connected there? I don't see how to get the head light pull switch out in order to remoce the face plate.

Everything else appears to be okay unless there could be a connecton issue where the tach filter wire plugs into the distributor connection but the way they snap together, I don't hardly see how that would possible.

 

[roger longman]

Hi, if you cannot squeeze the triagular metal clip located in the stem of the knob , do as I did and pull off the knob and then remove the clip and reinsert it before remounting. Roger.