Speed sensor output Voltage

Speed sensor output Voltage

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Gavster

Original Poster:

34 posts

272 months

Tuesday 11th February 2003
quotequote all
Hi everyone,

Just been testing a few of the sensors on the car and the speed sensor output is a little confusing. The bible (which is geat BTW) specifies a 0-12V output swing as the car moves. The output from my sensor is approx 0.25 - 4.5V possibly indicating either a faulty sensor or the fitting of a sensor with a 0-5V output. The ignition is on and the connector plug disconnected from the ECU. The oscilloscope output looks fine apart from the low voltage.

I guess that it may also require the ECU to be connected to 'Pull' the voltage up to the 12V rail.

The car has been de-catted (by the previous owner), could this 0-5V output be possibly part of the mods?

Has anyone else seen a 0-5V output from the speed sensor?

I have also noticed that the fueling resistor is the wrong value for a non-cat car but I assume this is taken care of by the ECU chip change.

Thanks for any help guys,

Gav


Gavster

Original Poster:

34 posts

272 months

Tuesday 11th February 2003
quotequote all
Cheers for the info Steve,

With regard to the ECU chip, it does have non-cat written on the EPROM so I guess the de-catting has been reasonably performed.

Is the resistor normally changed during the de-catting process?

I have noticed the speedo jumping occasionally recently, but in general it has been OK during the time I have had the car. Guess I had better get under the car and see what voltage the sensor is being supplied with.

I was only pushing the car backwards and forwards so it could be a speed related problem. I know that some speed sensors will only output 5V. It may be possible that an incorrect sensor has been fitted but has enough output to just operate the speedo. Do you know the input switching levels for the ECU?

Thank you for your help,

Gav