Took my 1987 S4 to a specialist garage to have a Power steering leak fixed, they replaced a hose and cleaned up the area. We noticed that the tach was not working they asked I bring it back another time and they will see if they did something to it. Havent had time to do so they are 35 miles away) Since then I have discovered that the odometer stopped working at the same time plus some of the various system warning lights on the Tach side of the dash no longer work. Is it possible they did something to cause all this at once???
I cannot see any relation between replacing power steering hoses with speedometer/tach issues ... there is nothing up front on the driver side of the engine compartment involved with the tach/speedo.
Sometimes totally unrelated items happen at the same time. My poor mechanic has to explain this often to customers.
The tach/speedo issue could be something as simple as a lose connector at the bottom of the instrument cluster. This generation of Porsche 928 has a flex circuit that connects all the items in the instrument cluster. Removal and inspection may yield the answer.
Check the wiring to 14 pin connector under the hood on the passenger side.It has a tendency to deteriorate. I have a 86 that I am rebuilding the engine I found the wiring harness that runs from the 14 pin connector across the front of the engine was burned, before I found this I had the same problem. I replaced all of my instrements with late model counterparts.
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