[Gmecm] Tachometer circuit question

[WopOnTour]

Ron
Something of that vintage V6 does not use a the ECM as part of the tach 
display function. There is a wire that directly connects to the cluster's 
tach terminal from the DIS module itself.(Forget which pin but can get it if 
you need it) I believe there's usually a tach filter that connects to the 
DIS, I've seen those go bad, I'd try changing that next (assuming it's all 
still connected)
Good Luck
WopOnTour

----- Original Message ----- 
From: "Ron Drew" <rjdrew at comcast.net>
To: <gmecm at diy-efi.org>
Sent: Sunday, March 11, 2007 11:32 AM
Subject: [Gmecm] Tachometer circuit question


>I have a 1988 Cutlas Cierra (2.8L) which the tachometer gauge has not 
>worked since I purchased the car. The schematics that I have indicates that 
>the ECM gets an RPM signal from the ignition module via white wire. Other 
>than this, I can find no other reference in my manuals to the feed circuit 
>for the tachometer gauge. I assume it would be similar to the VSS circuit 
>(the pulse train is fed to the ECM which applies a scale factor and outputs 
>the scaled signal to the tachometer).
>
> This is what I have tried so far:
>
> - Swapped the ECM.
> - Swapped the tach (I purchased a spare instrument cluster from a junk 
> yard).
> - I did swap the ignition module for no other reason than I was running 
> out of things to try.
> - I have not tried to ohm the tach feed circuit since I am at a lost as to 
> what circuit specifically supplies the signal to the tachometer gauge.
>
> Can anyone offer any help?
>
> Thanks
> Ron Drew
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