Q. Hello Mr. Ciulla, My name is Jason and I have a 1999 Subaru Legacy Outback with 60,000 miles. The speedometer stops working periodically along with the odometer. My 1990 Honda Accord did the same thing and I replaced a speed sensor on it to fix it. I don't know if the same thing is wrong with my Subaru.
I looked to see if I could find a part on the Subaru that looked like the one I replaced on the Honda but no luck. Could you point me in the right direction?
Thank you very much,
A. There are actually two Vehicle Speed Sensors (VSS). I'm going to assume you have a 2.5 liter engine and an automatic transmission.
The Vehicle Speed Sensor 1 (output shaft rotation sensor) is mounted to the extension case (from the outside of the case). The sensor outputs a pulse signal which is transmitted to the TCM where it is converted to vehicle speed.
The transfer clutch drum is connected directly to the rear wheel driving propeller shaft. Vehicle speed sensor 1 on the AWD model detects rear-wheel speed.
Vehicle Speed Sensor 2 provides vehicle road speed information to the ECM. The ECM uses this data to properly determine ignition and fuel delivery curves. The sensor consists of a reed switch and magnetic rotor turned by the speedometer cable.
One rotation of the magnetic rotor opens and closes the reed switch four times, producing a digital signal which is converted to vehicle speed by the ECM. The sensor operates whenever the vehicle is moving with ignition ON. As the transmission rotates, the speed sensor sends a pulsed on/off signal to the ECM.
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