Wanting to confirm the VSS Buffer signals in a 1988 GTA. The input signal from the transmission is a sine wave and the outputs to the ECM, Speedo, and cruise are square wave. Does anyone know the voltage of the outputs ot the ECM and Speedo? Is it 5V or 12V?

I'm trying to hook up a EZ-TCU from TCI to run a 4l60E transmission behind a 383 SBC. It outputs a 12V square wave signal. The speedometer worked when hooked to the 12v square wave output from the box for about 6 miles before it quit working and now the digital dash shows 0 mph and the odometer no longer increments while driving. This hookup was done after the VSS buffer box directly into the wire to the speedometer.

 

5v
Focus on the things that were changed. Hope you find it easy.

 

So if the OEM signal is 5v and the TCI box puts out 12v that might explain the issue.

Anyone know if this might cause the speedo to stop reading after a certain amount of time in use?

Although after some experimentation involving a spare Autometer speedo, I think this might be a wiring issue since it won't register speed on it either.

 

The VSS buffer doesn't output any voltage. It can only provide a ground to drive the pulse stream. The device it is connected to (speedo, cruise, ECM), provides the voltage via a pull up resistor.

The ECM pulls the pulse stream up to IGN+ voltage. I have no idea what the speedometer and cruise pulls the voltage up to.

RBob.

 

I have the same problem I went 383 sbc and use a us shift controller for my 4l60E but don't where to tap the tan wire for speedo from us shift into the buffer box. I have the digital dash as well.