Hello. Before yesterday I saw that at the dashboard speedo showed 200+ km/h at the idle. When I started to move, it jumped from the zero to max randomly, but mainly stayed at zero.
Yesterday, I saw the same behaviour, additioanlly got 0501 error and check engine light appeared.
I disconnected speed sensor socket and decided to the check amount of voltage which came there from the harness. It appears only with turned on ignition, which is ok. The strange thing I found, that with stopped engine and enabled ignition only, signal wire throws 10+ V. I thought normally it should gives 0V isn’t it?
A P0501 code is a bad speed signal. If the wires are OK, the sensor is likely bad. And likely shorted internally.
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Thanks, take it out from the gearbox and tested on the power supply.
As I understand, I supplied +12V to the dedicated piin, GND to the dedicated PIN, and between signal pin and +12V pin I connected a multimeter.
Trying to rotate internal shaft of the sensor (clockwise and counterclockwise). In both cases there is 0.4…0.9V shown.
Mainly this checking method is the same, but in my case with lightbulb I didn’t have a light.
https://www.youtube.com/watch?v=7BsZpQi0nIQ&list=LL&pp=gAQBiAQB
Why would it show 0 Volts with the ignition on only? The speedometer works with the ignition on.
Correct, for the igintion enabled, on the speed sensor socket appears +12 V between outer pins.
If ignition turned off, there is no voltage.
The VSS is likely a non-contact sensor. It relies on magnetic or inductive sensing from a rotating part. You cannot tell much of anything probing the wires other than it has power and ground. What you’re seeing on the signal line is the bias or pullup voltage on the detector. Normally, this sensor sees a square wave signal from a tone ring or magnet that rotates in relation to transmission output shaft speed. This is amplified and passed on to the controller through that signal line.
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VSS based on the Hall Effect, normally it should read 6 or 8 pulses per one rotation, as I know.
Ok, so as I understand I should concentrate only on outer pin (12V between them must be present).
You can always jack up the drive wheels and run the engine if you need to test the sensor while it is working.
