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Old 09-04-2014, 07:16 AM
v8volvo v8volvo is offline
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Join Date: Jun 2009
Location: Montana, USA
Vehicle: '86 745, '83 764
Posts: 1,618
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Sounds like you might want to check your charging voltage. You should read somewhere between 12.5-13v at the battery terminals with engine off, and 14v plus or minus a bit with engine running.

Is the fluctuation random, or is it just a difference between when the key is on with engine off vs when the engine is running?

Do you notice a corresponding fluctuation in the brightness of the dash lights, exterior lights, tone of the door chime, etc, or do you see it only in the movement of the instruments? If it is isolated to the instruments only, the little 3-pronged power supply board on the back of the cluster (in the middle behind the speedo) may be something to check for corrosion, loose connection etc.
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86 745 D24T/ZF 345k lifted 2.5"
83 764 D24T/M46 155k

Last edited by v8volvo; 09-04-2014 at 07:18 AM.
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