Rev Counter - 1987 190E Auto

[Matt Crooke]

Whilst driving along yesterday, the rev counter dropped to zero and has stayed there ever since. This is my first week in the world of Merc, and im unsure what the cause could be. I presume that the counters arent cable operated, so could a sender unit be playing up? All help greatly received. Many thanks. Matt.

 

[Matt Crooke]

Rev Counter

Found the problem, it was linked the the electromagnetic cooling fan! The switch that activates the fan at 100c was faulty, causing the fuse to blow each time it tried to switch on. It turns out that the fuse that protects the fan also does the rev counter and quite a few other electrical items in the car. A new switch and a new fuse later and the fan and the rev counter are working merrily away!!