I will make this simple because I am clueless .i have a 1986 Firebird. A swapped 350 sbc but the wiring appears to be factory. I don’t have a working speedo gauge . I changed the sensor. The yellow and purple wire coming directly off the sensor read 10V when the ignition is put into Access. It goes fine to the VSS buffer box. From there the green wire goes to the speedo which is fine. All the other wires were found to go where they needed. I just cannot find the end of the black wire with a white stripe down it( ground) it should be in the factory spot so I should be able to find it if someone can point it out.

so I’m basically asking where I can find the grounded end of the VSS buffer box. Any idea of where in the vehicle would be very helpful!

 

I think mine went out the fender and attached to the back of a cylinder head on the engine. '89 Firebird with 2.8L V6.

 

passenger fender or driver fender ?

 

I don't know. Car had been torn apart for 16 years before I even realized there was a ground wire out there and it was already cut out of my harness by accident. I just grounded it inside the car instead. I think it was a shared ground with the PASSkey module and the OBD I connector under the dash.

 

hmmm I guess I will keep searching then! Thanks I will search more vigorously inside the engine bay then

 

Use a voltmeter ( or test light ) & just check to see if PIN 'M" of C207 has ground or not.

The Buffer ground is part of the ECM harness in some cars and usually on a stud with nut holding it to the back of the head. Often removed when ECM harness gets ripped out.

Here is the wiring schematic for the 86 Firebird VSS Buffer;




This thread contains a picture showing the (YELLOW) VSS Buffer on the floor of an 88.

https://www.thirdgen.org/forums/elec...connector.html


If your ECM harness was removed and you lost this ground, you can re-apply ground to this thing any way you want. You can splice into the BLACK/WHITE stripe wire @ PIN 'M' @ the C207 connector, or splice into the BLACK/WHITE stripe wire right at the Buffer Plug,... then screw the other end of the new ground wire to the body - anywhere - it's a ground wire. ( soldering and heat shrink recommended ) You might need to scrape the paint/sealer from the body metal to be sure that you have a good ground, but as long as you screw the ground wire to the body, you'll be OK.

 

Here is the C207 connector,... pass side under the dash.


https://www.thirdgen.org/forums/elec...cm-wiring.html