Ok pulling out the ECM (LG4) and removing the harness. My 86 TA has the electric speedo. From the searches I've done I've read that the VSS sends signal to the speedo then from the speedo to the ECM correct? Or is 86 different? Can I remove the computer and still have the speedo work correctly or will I need to change or modify something?

 

My 86 had a cable to drive the speedo.
The wires from the VSS go straight to the ECM (165).

 

I haven't removed or unplugged the ECM so can I just eliminate all the other wires and just keep the VSS wires hooked up to the ECM? Would that keep the speedo working?

 

Youd need a buffer box to drive the electric speedo

My old 86 was also cable driven, so you may not have to do anything

 

Hey Mike, Does your car have the digital dash our gauges? On the gauge cluster the speedo is cable driven and certainly doesnt need the ECM. From looking at the factory wiring diagrams, the VSS signal is spliced and feeds the speedo and the ECM. The buffer is in the VSS circuit ahead of the splice. I would think that even the digital speedo will work fine without the ECM.

 

Pocket unfortunatly no speedo cable on my 86 TA. It's VSS and does have the buffer box. The buffer box is sitting right next to the ECM under the dash.

ASE Doc so the VSS is routed to the ECM but it's spliced before it hits the ECM on the 86? My TA has the regular gauges.

 

If the buffer box is in place already then you're set. Just dont cut out the VSS wires

 

Pocket is correct in saying that with the buffer in place, the speedo should work fine without ECM. The VSS sends an ac signal to the buffer. The buffer converts this to a digital signal and sends it to the speedo and the ECM. There is no feedback from the ECM to the buffer. Based on my experience, the VSS, buffer and speedo arent going to care if the ECM isnt there. Just dont cut any of the VSS- buffer- speedo circuit and youll be fine. Do you have access to factory wiring diagrams? Your local library should have All Data or Mitchell on demand where you can print the pages you need. But the Helms factory manuals are nice to have. Theres a seperate electrical book thats pretty cool.