300 SDL Instrument Cluster problems
 

I just recently purchased a 1987 300 SDL. The odometer didn't work. I followed instructions how to remove and check and replace gears. I found the e1 and e2 gears were missing teeth and ordered new ones. I put the cluster back in and now having weird problems.

Speedometer doesn't work at all when it worked previous to my dis-assembly

Turn signals don't hear the flasher clicking nor green arrows. When headlights turned on left arrow is constant green whether turning or not, but can hear the clicking of flasher. The actual turn signal light bulbs flash outside the car. The right turn arrow doesn't come on inside the car but works outside.

Other gauges work fine with the exception when the headlights are turned on. When on, the oil pressure goes to 0, temp maxed out, and fuel full. Turn lights off and back to normal.

What can this be? I've tried searching for this problem and didn't find much.

Are you sure you got the round electrical plug installed correctly?

-J

What compu_85 said. The connector has a D shaped center peg to clock it properly on the board. The pins make contact before the peg engages the board causing strangeness, and in my case burning a couple of gauges. Not MB's finest engineering moment.

Sixto
87 300D

Could very well be. I put it back in the dark with a flashlight. I will check today. What is the single round plug that goes on the stud coming out of the speedo for?

The speedo and turn signals are powered by the 6 pin connector that is directly on the back of the speedometer. If you are looking at the back its down and to the left of the single round plug.

I'm not sure what that plug does either.

I do know that: power, ground, speed, turn signals are routed through that 6 pin socket. Only 5 are used though.

I've got the same problem with my 1986 300 SDL. My plug center "D" shapped center piece is broken off. I know the allignment is off. Previously my climate speedo / odometer wasn't working. The climate control was working when the key wasn't fully engaged. When the key was fully engaged, the clomate control worked intermittently.

After rotating the plug on the rear of the cluster, the speedo still isn't working, climate control works much better (but not perfect). The radio, and accessory light aren't working. Can someone offer some suggestions. Maybe even a picture of the attached plug at the proper angle? I did find a diagram of the pins and their corresponding numbers. But there are no number on the circuit board to aling.

Sorry for all my babble, I was attempting to be clear and complete.

Ron

Can you tell the flat edge of the remaining stump of the index tab on the connector? Maybe you can eyeball flat edge of connector and flat edge of gauge board as a best guess.

Request someone with an SDL to tell you the color of the wire at the topmost position as installed.

Sixto
87 300D

Probably the speed sensor connector for cruise control.

Sixto
87 300D

Yes, the single round plug is the speed sensor output for the cruise control, climate control, and radio.

-J

Thanks guys for the info. I can not identify any part of the "D" plug stub. It actually broke off into the backing, leaving nothing for identification. That is why I tought a picture of the connected plug may help. It seems we're on the right track.