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My 86 mod Spider was out of use for some months due to repair work on the cars body. When starting up the car again the speedmeter was dead. I have not been touching the speedometer when repairing the car. Any advices?
Earthing?
Other?
 

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There is a miniature potentiometer attached to the speedometer's printed circuit board that is used to calibrate the display. These mini-pots are prone to continuity loss between the wiper arm and the coil windings as a result of dirt, debris or minor corrosion. This tends to occur more often after periods of inactivity, or certain storage conditions. The loss of current flow causes the speedometer to read incorrectly, or not at all. Nine times out of ten, the inop condition of the speedo can be resolved by extracting the gauge from the instrument cluster assembly, spraying electrical contact cleaner on the mini-pot, turning the potentiometer's arm back and forth a few times with a small screwdriver, then returning the adjustment arm to it's starting position.
 

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if both speedometer AND mileometer/tripmeter counter is not working (you'll have to drive around a bit to tell)
then
first check would be fuses 7 & 8
second would be the short speedo cable from gearbox to impulse counter
third would be wiring/connector from impulse counter to speedo instrument

if only speedo is out, but mileometer counter is working, then it is an internal fault in the instrument.
 
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