Dying tach? - PeachParts Mercedes-Benz Forum

190D22 · #1 06-25-2002, 12:39 AM

My tach sometimes doesn't come up on start up. I have to flick the cluster for it to come on. It doesn't die when the car's running, it just doesn't come on at start up. It's not every start up, but it's been doing it more often lately. Any ideas what the problem could be? Thanks.

Ducati · #2 06-25-2002, 01:15 AM

Do a search in the archives of this forum for "Cigarette Butt Trick"...really - this is no joke. You can do a temporary tach repair with a cigarette filter. I have never done it, but when my tach starts to act up (and I know one day it will) I remember this discussion from many months ago.

190D22 · #3 06-25-2002, 01:45 AM

Well I don't want a temporary fix with this... Are all of these descriptions true with my 190? And is all of this on the back of the cluster or what? Thanks.

surfblau · #4 06-26-2002, 08:04 PM

The cigarette butt trick won't work for 84s, they don't use a tach amplifier (as a very helpful other member informed me). I had a similar problem before.

I pulled the instrument cluster to work on the odometer and cleaned the contracts on the tach and its input cable.

From not working at all, the tach then started to work in damp weather, then it started working all the time. It could also be something to do with damp weather....

There may be a post out there somewhere with my name on it that could help.

later

190D22 · #5 06-26-2002, 08:28 PM

Yeah it makes sense that it'd be bad contacts with the tach, because I give the cluster a light tap and it comes up. But it doesn't give weird read outs and it doesn't go intermittant on me when I'm driving. It just doesn't register all the time when I start the car. How hard is it to clean the contacts on the tach? Do I have to remove the cluster completely? I don't want to because there's lots of stuff to disconnect, and my main worry is the oil line, I don't especially want oil leaking inside my car! If I can get to the plug with just disconnecting the speedo cable that is fine, I've done that to change the illumination lights. Thanks for the help.

surfblau · #6 06-27-2002, 01:19 AM

You may be able to scrape off the contacts and make sure that the connected is firmly attached without removing the cluster, but it was easier for me to do it with the cluster out.

There are lots of posts on removing the cluster. I ended up using a coat hanger on the right coming from the front and my hand from behind on the left. You have to remove the plastic panel below the dash and then disconnect the speedo cable, oil pressure line and a couple of electrical lines.

It depends on what you think is fun. For me it took a total of about 1.5 hours the first time moving very slow. Now I can do it in 15 minutes. Realize that this is not by any means a sure thing to cure this problem.

As for cleaning the contacts on back of the tach, I just steel wooled them. Part of the problem on mine also may have been that the plastic connector was not squarely seated on the back of the tach (but that is just a guess, possibly the last person to get behind the dash didn't really make sure this connection was good).

best of luck

190D22 · #7 06-27-2002, 01:36 AM

Well I have had mine out far enough to change the bulbs. I had to take the lower kick panel off, and disconnect the driver's side air vent. Then i just simply push the cluster from behind, it pops right out, I feel around and disconnect the speedo cable, and HOPEFULLY this will give me enough room to do the tach cable. We'll see. Thanks for the replys!