MyE28.com

Hi everyone

Tach, temp and fuel are good, but speedo/odo and naturally econo are dead, never seen them alive. I've already bought the 3 piece gear set and had them replaced. When tested at the bench, it works fine. I thought it was too delicate a job to handle myself, but these days I got so used to it that pulling the cluster apart takes less than 30 seconds, and disassembling at home takes another 60 seconds.
After reading quite a many questions and answers here, I lined up the usual suspects. Sanded and cleaned the connections of fuse 6 and installed a new fuse, borrowed and plugged an intact diff sensor from a friend, cleaned the sensor plugs, measured the connectivity of the line from sensor to cluster, still nothing. 

VIN says my euro 525i was produced in Feb 1982. Upon disassembling, I found out that the tach is date stamped Jan 1982.

 

But the main frame and speedo are dated Oct 1984.

 


 

Someone has clearly fiddled with it (and clumsily too, the SoB bent the needles. I somehow lined up the km needle, but tach needle is a mess. Haven't searched about that yet, I'm sure someone else has dealt with this kind of stuff before).

Anyway, I thought it's an electrical issue within the speedo, so cleaned and checked (with an ohm-meter) the speedo board just to find out everything OK. That's when I noticed that the four pins on the SI that connects to the speedo don't match with the sockets there. Only one of them plugs in.
  


 

As far as I see, speedo has no other connection whatsoever, so this must be it. I couldn't find any info on which pin brings what. No, I don't have a Bentley (yet).

What do you suggest I do?

Here is my speedo from a Feb 86 cluster.


 

As you can see the four connectors would line up with 1-4 on your board.

It would seem that your very early speedo unit differs some what. I guess that you need to find a later speedo or earlier cluster. 

JohnH wrote: Feb 07, 2025 6:39 AM Here is my speedo from a Feb 86 cluster.

It would seem that your very early speedo unit differs some what. I guess that you need to find a later speedo or earlier cluster. 

I have disassembled several e28 clusters and the pin configuration is like Johnh's image. The speedo you have installed is from an e30...that's why the pins don't match. You should look for an e28 speedo from the early version, until the beginning of '86. The clusters after that are different.

 e30 speedo

If you look at Aldos board you can see the pin identifiers, + A xx 31. 31 is battery negative . I cant quite read xx.

Below is the underside of my speedo/odometer which has pin ids of A + - (aka 31) and xx.
 
You should be able to make up four wiring connectors.
Let us know how you get on. 

edit: Just checked it again and xx is 31b.
 

Aldo and John, thank you very much for your responses. Looking at the two pictures you posted, it's gotta be this way:
 

 

We can call this SOLVED.

One of my friends, an electrical engineer (a youngster), was interested when talking about this issue. He's also into classic cars, so offered to lend a hand. I visited his office yesterday, we grabbed a plug of this kind:
  

Then he pulled out the pins. I showed him which connects where according to the photo in the previous post (thanks again, Aldo from Chile and John from ClaptonLand) and he made the soldering.

This is the Speedo side:

 

... and this is the SI unit side:
  

Completed, it looked like this on the bench:
  

... and like this on the assembled cluster:
  

The plug fits into the abyss behind the cluster without problems. Speedo, odo and tripmeter started working. Econo didn't, but I leave that for another time, since this will be enough to get me through the long due legal inspection.

When returning home, speedo seemed to be showing slower than actual (I may be wrong), today I'm gonna test it with wife's vw tiguan and report back. 
  


Thanks to everyone who's involved, and those who keep this board alive. Hope this will be useful to someone in the future. I'll be back with more questions about other stuff.

(Please warn me if this many photos is a no-no. It's a habit from plastic modeling forums to show what you do in steps.)

Guess I've located the diagnostic connector, something same size is lying a little down below, someone must have left it there. If I can pull it up with a piece of wire or something, I can reset the service lights (all red).


 

Tested at different speeds till 80 (that's km/h not mph). What I said is true, both speedometer and odometer read about 75 percent less than actual values. Maybe tyre size, maybe something else. All comments welcome, but lemme pass the inspection first and deal with this afterwards.

Edit: Last year I had the speedo gears replaced with E28 gear set, thinking that was the problem. Since the speedo turned out to be coming from an E30, can it be that E30 gear set is of a smaller diameter? Maybe what I ve got there now is bigger, that's why it revolves less, hence the smaller values it reads?

Looking good.

There are two diferent E30 speedos. One made by VDO and the other by Motometer. I think all E28s are VDO. Its written on the gauge face. I think yours said VDO. Its a bit fuzzy.   

I believe that the E30 and E28 VDO speedos are the same apart from the gear wheels. The E28 gears are E1 12 teeth, E2 48x12, E3 48x17, E4 43x34 and E5 16x26. Gears E1, E2 and E3 are the ones that get changed.

A few pictures to keep the count up!