1984,300d tachometer

[co.aulakh]

thanks for your quick response.
tachometer does not work.
before it stopped it used to come on when i pressed the air conditioning buttons.
there is no amplifier under the hood,
there are no relays on the right passenger footwell since this is not a california car.
i checked the two relays under the hood controlling the aux.fan and the compressor and they are o.k.
would appreciate a diagnosis.are there any other relays that i am not finding????

[Benzmac]

If it was by any chance an 85 built in late 84, it might have an overvoltage relay behind the glovebox mounted to the right hand wall of the car.

It could be the diagnostic socket is faulty. Look on the L/F fender undere the hood there will be a small black round cyl. That is the control unit that outputs to the tach.

------------------
Benzmac:
1981 280GE SWB
1987 16V
ASE CERTIFIED MASTER AUTO TECHNICIAN
SERVICE MANAGER FOR 14 BAY FACILITY
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM

Hi,
There were only two versions of tach wiring for that car. If you have no tach amp, you have a control box in the right kick panel(behind the plastic to the right of the floor in the right side of the car). Otherwise,it never worked.This version of the system also ran from a separate wire to the + side of the battery(i.e. at the battery terminal). I have seen these connections forgotten after battery replacement.Look again.
Regards,
Randy D.

------------------
W.R.Durrance
ASE Master Tech
Mercedes Tech 19 Years

[co.aulakh]

thanks guys
i will get back to you after i check these suggestions.
regards