No Speedometer or Mileage


Old 08-06-05, 11:39 PM
Old man
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Unhappy No Speedometer or Mileage

I have an 86' Cougar, 3.8l engine, automatic trans.
The problem is with the speedometer and mileage readout, it is a digital unit.
I have replaced all the lightbulbs in the dash and it backlites just fine. But will display no numbers in the mileage or speedo. I have had it all apart trying to figure this out, it appears the readout itself is an LCD unit that connects to the circuit board with ribbon wire typ connectors. I have looked over the circuit board for obvious bad components and can spot nothing. It lights up a solid green, and has a few lighter green speckles in there.

Anyone know anything about these? I am finding almost no info on these units, seem like they are top secret or somthing.

Any info will be appreciated, as speeding tickets are expensive.
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Old 08-07-05, 12:57 AM
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try taking a look at the vehicle speed sensor maybe that is loose or dead
Old 08-07-05, 01:29 AM
Old man
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I thought about that,but that should not keep the total mileage from showing, should it? When the car is moving I know the speed sensor should tell it what numbers to change to, but it is not even displaying '0' when sitting still, it is just blank.
I cannot find any info on this stuff, Ford just says they have to send them out for repair if there is any problems with them, and quite frankly the repair will probably cost more than the car is worth.
I can't find any schematics or voltage references for the speedometer circuit at all.


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