Electronic TACH/SPEEDO problems - T56 VSS etc!

[Fiddler's Gold]

Everyone,
I have been out of town for quite some time, unexpectedly.

Background:
Dash seems to function ok. Fuel, Batt Voltage work but everything else is non-responsive. I do get some kind of "guesstimation" from the RANGE button but I don't know if that is accurate or not. Everything thing is lit up and appears to be capable of working.

TACH:
I come back and I am still faced with the same electronic TACH/SPEEDO not working issues. I have searched the archives and have been researching this issue heavily. I have a GM style HEI with TACH connector for the feed. What pin on the dash should this be conencting to? Is it ok to run this wire directly with no tach filter inline? Could I split the tach send wire to both the manual tach with shift light and the electronic tach at the same time?

SPEEDO:
I have a replacement T56 :crazy (from late model Camaro) which I was told uses different VSS pulses than the 4+3 etc for the ECM and dash. Will the SGI-5 box from Dakota help in the conversion to the dash to get it to function? What type of other adjustments need to be made to the speedometer and what is the pinout/connectors for the speedo for the dash? Any help would be greatly appreciated. I think I am going to have a problem with the PO not hooking up the connections at the tranny and we will need to see if this is even possible at this point. I don't want to have to tear apart the tranny to get to the speed sending components. I think there is a wiring set leaving the tranny - lets hope that it is not melted or busted up. What would the proper VSS send wires look like?

Thanks so much for any/all help!
Andy

 

[Eagle85C4]

Is the tach filter still attached? Follow the tach lead off of the distributor and if it goes down to a small can attached to the head, then that is where the problem is. The capacitors in the filter are not heavy enough to withstand the voltage and the heat from the head and over time open up and cause an intermittant or no signal at all to the tach. I have a copy of the original schematic and have made new ones. The part is discontinued by GM.

 

[vigman]

Dash seems to function ok. Fuel, Batt Voltage work but everything else is non-responsive. I do get some kind of "guesstimation" from the RANGE button but I don't know if that is accurate or not. Everything thing is lit up and appears to be capable of working.


If the fuel,batt & oil pressure are working the rest of the dash is cool.

What pin on the dash should this be conencting to? Is it ok to run this wire directly with no tach filter inline? Could I split the tach send wire to both the manual tach with shift light and the electronic tach at the same time?

You could run both if the signal doesn't get loaded..in other words.. try it

On the dash module the "C" connector
( the bigger one) pin 5 is a white line which is the tach line , this runs across the dash to under the hush panel where the ECM lives.. It plugs into ( C238 ) then exits out the firewall on the pass side behind the distrib slightly twds the pass side.. the harness has all the fuel injection wiring stuff in it.

Can you not find the orig white wire under the hood?


I think there is a wiring set leaving the tranny - lets hope that it is not melted or busted up. What would the proper VSS send wires look like?

A yellow & purple wire .8 gauge ( medium) to a 2 pin connector.

As far as changing your shaft encoder.. I would first hook a stock one up to the wires and spin it by hand.. to verify the crkt works

then I would look into a mechanical adaptor to make the two fit correctly.. like a speedo gear reduction head.


Vig!

 

[Fiddler's Gold]

the hush panel?

Is that that big ugly black air bag looking thing on the passenger side? The wire doesn't go from the tach straight to the C5 pin then, everything goes through the ECM? Can you clarify the location of this for me and thanks!

What color is the wire from the ECM to the C5 then? maybe he just cut it and I could reconnect it.

Thanks
Andy