QuestionQUESTION: my speedometer is not working and my husband says it is the speed sensor how do i check this.
ANSWER: I'll need to know the year and model of your car in order to determine how the speedometer gets it's signal. If you follow up with that information, I can reply with advice on how best to check into your speedometer problem.
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QUESTION: it is a 2001 hyundai santa fe
AnswerYour vehicle has a speed sensor mounted on top of the differential of the transmission that outputs a square wave signal to the speedometer. The most checking you'll probably be able to do reliably is to verify you have power on the green wire when the ignition is in the "on" position and ground on the black wire.
To properly check the output of the sensor, you'll need an oscilloscope. The speedometer can be checked by applying a varying frequency square wave signal to the speed signal wire in the diagnostic connector, but this, too requires equipment you probably don't have.
If you've checked power and ground to the sensor, and they're both okay, chances are very high that the issue is with the sensor or the gear that drives it. If you unbolt the sensor and remove from the transmission, you'll see that it has a plastic gear on the end of it. If the teeth on the gear are rounded away in the center, the gear is probably the issue. It's been my experience that the sensor often breaks when removing. I typically just replace both the sensor and gear at the same time.
