The tachometer needle of my 97 EB climbs to 2500 rpm when the engine is running and stays there regardless of engine speed. With engine power off, it rests normally at zero. Earlier today upon start-up, the tach was moving erratically between the idle speed of 1000 and 2500, where it now stays fixed as of this writing.

I disconnected the battery for 10 min, in the hope of resetting the "electronics" but that did not work. Engine/truck operation is unaffected and behaves normally. Anyone who has encountered this problem? Any explanation/solution will be greatly appreciated.

 

Follow-up: Upon starting the engine this morning, the tach was working normally. Is a loose wire or a bad rpm sensor causing this problem? Anyone suggest where I should start looking? Thanks

 

Due to the erratic behavior of my tach, I decided to do it myself and remove/take apart the instrument cluster. I found a circuit board mounted above the center portion of the cluster that controls the gauges and cluster lights. I removed and re-seated all the connectors and got the tach to work properly.

Note: It is disappointing to see the 'quality' of Ford's electronics. The board uses ribbon-type connectors that had gotten brittle over time, resulting in poor connectivity. The board itself was ugly - rough edges, uneven soldering, etc. The outside portion of the metal housing of the gauges were all rusted up.

Since I've covered only 11k miles over 5 years in this Expy, I feel cheated. It's a race against time for all Expy users. I got to start piling up the miles before something else breaks...:-X23