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Old 08-08-2010, 11:55 AM   #1
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Default replaced PCM, now speedometer doesn't work

I replaced the PCM in my sister-in-laws 95 Bonneville with a salvage yard unit and now the Speedometer and Odometer do not work. Is the replacement unit faulty? Or did I pull a wire loose during installation?
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Old 08-08-2010, 12:39 PM   #2
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same amount of prongs in the wiring harness?
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Old 08-08-2010, 01:53 PM   #3
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swap the original back in, see if it fixes it. if it does, the replacement is junk. the odometer is driven off of the speedo signal anyway, so it'* likely the driver in the PCM for the 4K PPM signal died.
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Old 08-08-2010, 01:57 PM   #4
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95 PCMs are flaky. Swap back, if speedo works, get a different PCM. If it still don't work, then start checking the pins in the plug.
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