I am having problems with the tachometer on my 1988 190e. It hasn't worked properly since I bought the car almost two years ago, but now it sometimes is working (still inaccurate) and other times it is dead (no reading). Also, the outside temp. gauge has stopped working as well. Any thoughts on were to start in trying to fix the problem?

Another problem I am having is that when the A/C is working the performance does't drop off by just a litte, it drops off a lot and usually has to kick down to 1st gear just to get off the line. It seems to me that maybe I have an electrical problem. I had a guy test the spark plug wires and they seemed okay, but the #2 cylinder spike on the testing equipment was significantly shorter than the other cylinders.

If any one has some suggestions on were to begin looking into these two problems would be much appreciated.

Thanks,

Gards

You bought the car used. I would pull the instrument cluster and have a close look at the back side. The tach relies on a ground connection that travels the length of the cluster but originates on the speedo side (strip of copper on the plastic backing of the instruments). In the event that someone had rolled the odometer back or otherwise disassembled the cluster before you purchased it, they may have messed up the ground connection. Clean all copper strips you see back there and pay particular attention to places that are held together by screws.

Thanks for the tip, I will check that out with my mechanic. What is weird is that when the tach dies so does the outside temp gauge and the passenger mirror controller. Are these connected on the same wiring?

Thanks,

Gards

have you checked out your fuse for the circuits which are faulty?

I didn't check for any blown fuses because the tach, outside temp, and mirror controller would come back to life, so I figured that would not indicate that a fuse was blown. However, with that in mind I did check and none seem to be blown.

What is wierd though is that when the above mention come back to life they seem to go dead when the revs get higher. Is it possible that the volts are becoming too high and then something trips and knocks off line the above mentioned?

Thanks for the help.

Gards

sometimes the fuse may appear ok,but corrosion or poor contact may result in the problem you are describing-have you actually swapped the fuses of similar amps to exclude this possibility.?

I have not swapped the fuses with similar amps. I will give that a try and see if there's life in the tach. Thanks for the tip.

Gards

Gards

Even rotating the fuses in their respective holders can sometimes improve one with questionable contact.

Haasman

__________________
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)

Well Haasman suggestion of rotating the fuses led me to found that sunil190e-1.8 was correct, there was a blown fuse on number 10. So I thank both of you.

Gards

good to hear another problem solved

you know my car which is a190e but with a 1.8 litre,4 cylinder engine has fuse number 10(8 amps) which controls the cooling fan clutch circuit,the outside temp gauge,the heated exterior mirrors and the electronic tachometer(rev counter).

Glad to see it was a simple problem rather than the horror show that was my old 190e in the instrument cluster. I can't to this day figure out how somebody could be so ham-fisted yet still successfully roll the odometer back. The intermittent tach was what caused me to take it all apart.

P.S. - regarding the performance drop with the A/C - I can sell you (cheap) a new, never used sport cam that I got from Bekkers just before I decided to trade my 190e.