Land Rover Repair: rev counter, tps sensor, rev counter

Question
i have a 1996 p reg diesel disco the rev counter keeps jumping up as if ive put my foot down hard on the acc pedal but the engine doesnt race or rev up

Answer
Hi Steve,

sounds like your alternator is about to fail.  tach is linked to alt and the first sign of alt failure is a bizarre reading on your tach.  Once the tach no longer works, your alt has taken "the big sleep" and you'll have to swap in another one or repair the faulty one.

Another possible cause could be the serpentine belt that is slipping on the alternator.  Was it recently changed or removed?  Most local mechanics have trouble feeding this belt on our Disco's.  I've heard a few say " it just doesn't make sense to feed it that way..."  If the belt is slipping, the tach will bounce around and even stay low.

A final cause could be a failing TPS sensor BUT you mentioned that your engine is NOT racing or has high rev's.  I'd go with the alt or the belt first.

Best of luck,

JohnMc