My speedometer when running is going in and out

144,668 MILES • 4 CYL • 2WD • MANUAL
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KLUKEBAGWELL
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  • 3 POSTS
I was looking at your article on faulty sensors. My speedometer when running is going in and out. Could that be the speed sensor in the transmission? Should I check the sensors on the wheels? Corrosion on connectors? Anything else?
Mar 14, 2018 at 7:47 PM
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HARRY P
  • ✓Experienced Mechanic
  • 2,292 POSTS
Well it could be the speed sensor. But I would think that either the check engine light would be on or at least the ABS light would be on. If they are not on, then I would suspect a problem with the instrument panel or the wiring to it. Are either of those lights on? If not, do they come on for a second or two when you turn the key on but does not start the engine?
Apr 7, 2021 at 6:00 AM
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KLUKEBAGWELL
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No, neither of the lights turn on
Apr 7, 2021 at 6:00 AM
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STEVE W.
  • ✓Experienced Mechanic
  • 15,362 POSTS
I would start by looking at the harness that goes to the speed sensor on the transmission. That sensor is a simple pulse generator with a low signal, a corroded connector could cause problems. To check if it is the gauge or the sensor easily would be to connect a scan tool and watch the raw live data regarding vehicle speed, if the signal drops out when the gauge does it is likely the sensor/wiring. If the signal stays steady but the gauge varies it is likely a failing stepper motor.
Apr 7, 2021 at 6:01 AM
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KLUKEBAGWELL
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Okay, thanks a ton.
Apr 7, 2021 at 6:01 AM
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