Vehicle speed sensor
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Joined: Jan 2002
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From: Titusville, Fl
Vehicle speed sensor
Check engine light came on and I got a code for the VSS. so do I just replace it or what can I do to diagnose it further. Also does this have anything to do with the speedometer not working or is it cable driven?
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Dan,
#1. Not necessarily;
#2. Definitely;
#3. No.
You don't want to just run out and start replacing components without doing a little investigation first (unless, of course, you're a Chrysler dealer service department). Your speedometer is not cable driven, but is electrically driven by the VSS output pulses. If you have ever driven the car slowly with the radio off and no background noise, you may have been able to hear the "clicks" being read by the speedometer as it registers the pulses from the VSS - well, at least when it was working.
The VSS is gear driven just like the old speedometer cable would have been. The plasic gear on the VSS can fail just like the older plastic speedometer gears would fail. There is also an electrical connection at the VSS that needs to be clean and tight, and since it has been mounted on the side of the transmission for the last ten years it may no longer be clean and tight. It might not even be connected. It is also possible that the VSS has failed, but I would suggest checking the other items first. You'll have to remove the clip and sensor from the transmission to inspect the gear anyway, but the plastic gear is a separate service part number, so you may not have to buy a $90.00 pulse generator just to get a $9.00 plastic gear. If you're really lucky, you may only need to clean and reconnect the plug.
If you suspect the VSS, you can connect a penlight flashlight bulb or analog voltmeter to the two output terminals and spin the VSS shaft. The light should show signs of a small current being generated, or the analog meter needle should bounce in pulses as you rotate the shaft.
Just remember to use secure jack stands when you raise the car. We like to keep ALL our ThirdGen member around as long as we can.
#1. Not necessarily;
#2. Definitely;
#3. No.
You don't want to just run out and start replacing components without doing a little investigation first (unless, of course, you're a Chrysler dealer service department). Your speedometer is not cable driven, but is electrically driven by the VSS output pulses. If you have ever driven the car slowly with the radio off and no background noise, you may have been able to hear the "clicks" being read by the speedometer as it registers the pulses from the VSS - well, at least when it was working.
The VSS is gear driven just like the old speedometer cable would have been. The plasic gear on the VSS can fail just like the older plastic speedometer gears would fail. There is also an electrical connection at the VSS that needs to be clean and tight, and since it has been mounted on the side of the transmission for the last ten years it may no longer be clean and tight. It might not even be connected. It is also possible that the VSS has failed, but I would suggest checking the other items first. You'll have to remove the clip and sensor from the transmission to inspect the gear anyway, but the plastic gear is a separate service part number, so you may not have to buy a $90.00 pulse generator just to get a $9.00 plastic gear. If you're really lucky, you may only need to clean and reconnect the plug.
If you suspect the VSS, you can connect a penlight flashlight bulb or analog voltmeter to the two output terminals and spin the VSS shaft. The light should show signs of a small current being generated, or the analog meter needle should bounce in pulses as you rotate the shaft.
Just remember to use secure jack stands when you raise the car. We like to keep ALL our ThirdGen member around as long as we can.
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