PeachParts Mercedes-Benz Forum - View Single Post

JamesDean · #5 08-15-2013, 09:24 AM

If your other gauges are working its unlikely that the problem is a fuse but its never a bad idea to check. Make sure you look for corrosion, etc.

For the speed signal: What I would do is check to see if speed signal is present first. Grab a multi-meter. If it has the ability to read out frequency put it on that mode. Connect your + probe up to pin 11 on the cruise control plug and - to a ground location. The speed sensor will output 40-50 Hz at 25 MPH. If you flip to voltage metering you should see AT LEAST 2.6 V while in motion.

If you Do see the appropriate voltage/frequency then you can likely conclude that the sensor and cable are good.

There is always the possibility that the capacitors in the speedometer pod have aged and failed.

Another thing you can do is pull the cluster, on the 6 or 8 pin connector that plugs into the speedometer pod. You can check for 12V and ground. I can't remember the pinout off the top of my head but I think (If yourre looking at the back of the cluster) the bottom right pin is 12V and two pins to the left of that is ground.

Hope this helps!