VSS Signalling to ECM

[pfredricks]

Can anyone confirm that the signal to the ECM from the Vehicle Speed Sensor is grounding the +12 volts from the ECM? 2000 ground pulses per mile?

Does anyone know the duty cycle between ground and open for a steady vehicle speed? Is it 50%?

It is my assumption that the frequency is in proportion to vehicle speed.

TIA

[black87buick]

I haven't a clue but if I were trying to find out, the trusty Oscilloscope and driving the car may produce your answer.

[Keller]

Originally Posted by pfredricks

It is my assumption that the frequency is in proportion to vehicle speed.

That much I know is true. Not sure about the precise methodology.

[Keller]

Originally Posted by pfredricks

Can anyone confirm that the signal to the ECM from the Vehicle Speed Sensor is grounding the +12 volts from the ECM? 2000 ground pulses per mile?

There are many references that support 2000 PPM out there. Not sure if it is a ground or not.

[kenmosher]

It would be my guess that it's a 0-5v signal just because of the way it feeds into the clusterand the way most stuff works with a pull up resistor, but I could be wrong.

I dug around a bit and found this:

http://www.installationinstructions....I/vss-tech.pdf