tach problem PLEASE Help

[redfar]

I have a problem with my rev counter,on my w201 190 2.5 diesel.

I took out the cluster already to see if there's something wrong with the rev counter but I didn't notice anything,I bought a used one from internet to see if there is a fault in the tacho it self but it still don't work.
I changed the rev per minute sensor located at the bellhousing and still no signal.
I took the car to my electrician and told me the rpm sensor is ok,(is sending impulse).The problem is that the impulse is not reaching the tach.there is no impulse to the tacho.We checked all the fuses and they are all fine.
Is there a relay related with the tach?
Some thing that my electrician is suspecting is that the klima relay is not letting the impulse going to the tach,
Is that True?Does the Klima relay playing part with the tach?
Thanks

 

[Dieselman]

iirc there is an amplifier under in the fuse box. The amlifier makes a bad connection in the socket so fails to transfert he voltage from the crank sensor.

 

[redfar]

tach problem

Hi thanks diesel man
Is there an amplifier with the tacho in W201 diesel?
Where is exactly located?

 

[redfar]

Hi,
Today I solved the problem of my tach,
It was the Klima relay that failed,I don't know how.
I was with a friend that have a 190 and we started changing the relays and when the Klima relay was changed the tacho start working.

I noticed something but,
the tacho is reading a little bit high was the engine is slow.(no Gas)
It's between the 5 and 10 it's reading about 7
after it was reading 5.5/6.
Is the rev per minute sensor have any settings? because I took it out to check if the fault was the sensor,when the tacho was not working.