3-Series (E21, E30)Chat relating to the BMW 3-Series from 1975-1983 and 1984-1991 line. Specific models: BMW 315, BMW 316, BMW 318, BMW 318i, BMW 320/4, BMW 320i, BMW 320/6, BMW 323i, BMW 320i. E30 Family models include: BMW 325e, BMW 325i, BMW 325is, BMW 325ix.
So my odometer doesn't work. I consider myself lucky that every other gauge works. However, I'd like that to function. It is quite obvious that the gears are broken. I have sourced some new gears for a cluster for a very low price, problem being, they are gears for a VDO cluster and my cluster happens to be Motometer. What I need to know, is if I can go to the junk yard and get a VDO speedo module, replace the gears, and insert that module into my Motometer instrument cluster board. Are these modules interchangeable?
For anyone that cared or may come to care, the modules seem to be interchangeable. I replaced mine with one from a significantly newer e30 with a different faceplate and seemingly different configurations and it worked and tested fine. The original speedo module had K=7849 EG written on the face and went to 140 with only lines for 10mph intervals. While the replacement had K=7784 SAE written on the face and went to 150 with lines for 5 mph intervals. Also the one that came with the car had a lil board on the speedo circuit board right under and attached to the clear plastic gear cover. It had a magnet that turned with the mile gear. The replacement did not have this circuit. Not sure the function (some kind of mile counter for an OBC?) but it did not affect the function of the unit as far as ive noticed. So I finally have a complete dash.
It may not even be an odometer gear. Odometers used in E30s have an ac powered motor on them that turns the numbers, and those motors CAN burn up. I wouldnt go as far as to replace such a motor, just because when i took mine apart to modify the backlighting with red led strips the motors are soldered onto the board for the speedo. They look like a royal PITA to replace. Anyway, the red LED backlighting on my cluster looks AMAZING. So if your feeling creative when you replace your speedo, put in red LED strips. Theyre cheap, and the mod is quite simple. They were like 5 or 6 bucks shipped from ebay. And all you have to do is hook up the cluster since it isnt labeled, test the lighting leads with a DVOM to find out which side is positive, and then solder the LED strips onto the leads for the twist in lights. I also put red christmas light LEDs into the sockets for the lightbulbs with resisters so the temp gage and the fuel gage light up a little better.
EDIT: i didnt realize yours is an e21. It may not be electronic on these models. Sorry for any confusion, but the LED mod will still work on them.
Last edited by m20enginebuilder; 04-09-2012 at 07:31 PM.
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