Speedometer stopped working - 1992 400E
 

I have a 1992 Mercedes 400E and the Speedometer suddenly stopped working last week. I am trying to get some information and tips for diagnosing and repairing the problem. I understand that this model does not have a speedometer cable but rather has a transmitter sender unit? Are there any fuses that need to be checked? Where is the transmitter located? Is there anything to test or repair or do I just need to replace the transmitter? Other suggestions?
Thanks,
Kim

The 300E does have a speedometer cable. Perhaps the 400E is different.

Speedo
 

Hello Benz says this is the way to check operation so you dont replace a cluster for no reason on a 124.034 400E without a mechanical cable you should have a signal generator at left rear of trans. Checked all Fuses?
Remove the cluster and do a resistance check at cluster connector #5 multimeter between socket pins 3 (sensor) and socket 4 (grd) checking your harness and input signal -spec is 1.8k -2.2k ohms.
Also you could check ac voltage signal at same terminals should be >0.2v ac at Ten miles per hour.
Voltage at cluster same connector socket pin 2 is circuit 15 supply v and socket pin 4 gnd should have batt voltage key in pos 2
good luck Tim

If there is a signal generator on the transmission, is there also a transmitter or receiver on the speedometer?

more info on Speedometer and instrument cluster out
 

Thanks for the reply. I was looking at the problem again and I have some more information. Besides the speedometer and odometer being out, I noticed that all of the other instruments except for the clock are also out (Oil pressure gauge, fuel gauge, temp gauge, and tachometer are out). So I think this means it must be a fuse, right? I have not located it yet.

Two other clues that might be related:
1. the ABS warning light is on now.
2. low level buzzing noise on the left side that quietens when the turn signals are turned on.

Thanks for any other insights.
Kim

Speedo
 

Check fuses 5 & 6 (replace them!)

And beware of fuses that look OK but are really not OK. Sometimes they get hairline cracks.

Thanks for the help everyone! It was an 8A fuse: the one that is labeled to include the "Tachometer, cluster,...". It had a hairline that I could not see until it was moved. Mercedes fuses seem a little fragile!!
Thanks again,
Kim