1999 s80 t6 geartronic. speed control sensor/tacho

[les & reilly]

would anyone be able to tell me if the speed sensor/tacho sensor should read a closed circuit with a multimeter, or a resistance?

it is situated on the right hand side of the gearbox driveshaft housing with two wires into it.

any advice would be appreciated as i havent got the finances for the stealer dealers to check it out.

regards.

les northeast uk

[billofdurham]

Below is a reply from Les to a comment I made in an email about the use of a multi-meter. He asked me to 'paste' this onto the forum as he did not know how to do it.

The reply was to the point I made about multi-meters and my lack of knowledge on the terms such as "closed" circuit. It may be helpful for others.

continuity is the measurement in ohms, when there is continuity, it is called "closed" circuit (like a switch being on or closed) and an open circuit means the opposite, no continuity,
hope this helps.

i have been reading some of the posts "vss wehicle speed sensor, and i understand the circuit should not be open, there should be continuity.

i tried measuring continuity across an abs sensor which is a very similar component. measuring approx 587 ohms. if there wasnt continuity (like my vehicle speed sensor reads) i would suspect that sensor to be faulty.

Bill.

[les & reilly]

thanks for that bill.

im sure the paste`ing you did will help others to understand how to test some components which may be the cause of a fault.

my auto xray read a code similar to what ive discovered with my vehicle speed sensor suggesting; open circuit between gearbox and tcm. or shift solenoid s2/b stuck or open circuit.

by doing various tests, such as a continuity test on all switching circuits and putting voltage through the solenoids in the gearbox i believed the internals to be ok.

a diagram is needed to know which wire goes where, and care not to put voltage through an internal switch causing a dead short.

a voltage teast is easily done by having a negative lead connected to battery "-" and a 12v bulb connected one end to the battery, the other connection of the bulb with a wire and probe on it for testing.

this way, if the circuit to be tested is "closed" then the bulb will take up the current without causing any internal damage to the gearbox.

i hope i have explained this to be understood.

les