[Gmecm] Tachometer circuit question

[dgilbert78 at juno.com]

Ron: I am not sure about your 88 olds, but the 87 Ek Camino with a 4.3
and external coil. If you have a HEI with coil in the top of the dist,
then there is a TACH port on the dist usually. If you have a external
coil then the TACH wire comes from that to the tachometer, ECM plays no
role in the tach function, now thats an 87 El Camino, since your have an
88, I am just assuming its similiar
good luck
Darryl..
On Sun, 11 Mar 2007 14:32:41 -0400 "Ron Drew" <rjdrew at comcast.net>
writes:
> 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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