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'93 Astro LT Ext w/ FE3 (RWD), 7 Passenger, Dutch Doors, Med Teal, 4.3 V6
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I wonder if a previous owner had it calibrated for larger diameter tires, then put the originals back on it when he sold it.
 

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Registered
'93 Astro LT Ext w/ FE3 (RWD), 7 Passenger, Dutch Doors, Med Teal, 4.3 V6
Joined
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236 Posts
Except, we've owned the van since 99 and have never done anything with the rear end gears.

Also, The VSS is reporting the correct speed, as confirmed by GPS. This indicates the PCM is calculating correctly from the pulses/min it gets from the sensor. If the gears has been changed, the PCM calculation would be off.

I'm convinced it has to be something in the cluster, because the VSS is accurate and the cluster is supposed to simply display the calculated speed.
Is there a reset procedure? Something like this:


Or maybe just disconnect the battery and wait a few hours for the ECM to reset. I read that on some cars you disengaging the negative battery cable, then step on the brake pedal for a few seconds.
 
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