speedometer/tachometer/check engine light, speed sensor

210,000 MILES • 4 CYL • 2WD • AUTOMATIC
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6PAC-MAN
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  • 5 POSTS
speedometer works sometimes and not others, and tachometer will fluctuate. I have check engine light also. Transmission rebuilt. runs/starts/drives/shifts just fine.
Is this a speed sensor issue, and if so, how many are there and where are (they) located? Thanks again! Randy in Florida.
May 15, 2019 at 4:41 AM
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JACOBANDNICKOLAS
  • ✓Experienced Mechanic
  • 110,244 POSTS
Hi, Randy, and welcome to 2CarPros.

I have to be honest, a speed sensor is my first suspect, but we can't be sure until it is either tested or you scan the computer for diagnostic trouble codes. Since the check engine light is on, there will be codes stored. I noted that you are a mechanic. Have you checked codes?

As far as speed sensors, there are two on the transmission. One is a main shaft sensor and the other is the counter shaft speed sensor. I attached pictures of both. Check to make sure the wiring to them is clean and tight, not corroded or damaged.

Do this and let me know what you find.

Joe

May 15, 2019 at 1:17 PM
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