Instrument cluster and speedo related problems.
Moderator: martauto
This is an ongoing issue as most of us are aware of and its got a pretty straight forward cure : Diff sensor, signal wiring and cluster. Replace one or all of them and thats usually problem solved. The more curious or brave of us sometimes dig a little deeper as in opening up the cluster and looking for the obvious. I finally got round to this job yesterday and found to my dismay that it really wasnt worth it. Other cars 25yrs old may have had a fighting chance but BMW were way ahead of the competition even then. The PCB is double sided, heavily dependent on micro-processors and thickly laquered. Its well designed and a quality part. You would look very hard to find a dry joint and a component burn out would be hard to see. The signal from the pulse generator at the diff will be converted and decoded on an IC. I think that looking beyond cleaning the two multi-plugs is probably pointless so if you encounter this issue just go and source a complete cluster.. which I am going to do right now..
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Brianmoooore
- E30 Zone Team Member
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- Joined: Mon Jan 10, 2005 11:00 pm
The diff. pulse processing is on a small daughter board, behind the speedo itself. It suffers from dry joints where the pins that connect it to the main board is soldered in place.
The double sided board is commonly known as the SI board, and the only practical servicing possible on this is to replace the batteries, and then only if they haven't leaked. It is very unlikely that there will be a dry joint on this board.
The large mother board in the back half of the cluster can suffer from cracked joints where the coloured sockets are soldered to it, but I believe this is only as a result of rough handling by someone who doesn't realise how to release the plugs. There are two soldered joints, holding a large resistor in place, near the temperature gauge, and the soldering on these will always be cracked or very 'dry', unless they've already received attention.
If you do source a replacement cluster, I strongly recommend that you test (at low temperature) the batteries, or replace them as a matter of course.
The double sided board is commonly known as the SI board, and the only practical servicing possible on this is to replace the batteries, and then only if they haven't leaked. It is very unlikely that there will be a dry joint on this board.
The large mother board in the back half of the cluster can suffer from cracked joints where the coloured sockets are soldered to it, but I believe this is only as a result of rough handling by someone who doesn't realise how to release the plugs. There are two soldered joints, holding a large resistor in place, near the temperature gauge, and the soldering on these will always be cracked or very 'dry', unless they've already received attention.
If you do source a replacement cluster, I strongly recommend that you test (at low temperature) the batteries, or replace them as a matter of course.
Mmm..have to take a look- see at that daughter board and resistor then before consigning it to the landfill. Worth taking it out again and having a go. Got someone on here just down the road who has some clusters. Are the lithiums bog standard camera shop jobs?
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Grrrmachine
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