Tach, temp, mpg don’t work. Service lights work.

[dmw]

1987 325i convertible. Tach, mpg, and temp gauge (reads cold when warm) don’t work. OBC computer is dark but otherwise works. Service indicator lights work. I replaced the batteries on the SI board and they test ok. Fuses 10, 12, 21 are ok. What should I check next?

[82eye]

your SI board batteries sound like they've had it. cluster will have to be removed and batteries replaced, or the board will have to be sent off to bavrest or other electronic restoration company to be fixed.

[dmw]

your SI board batteries sound like they've had it. cluster will have to be removed and batteries replaced, or the board will have to be sent off to bavrest or other electronic restoration company to be fixed.

I replaced the batteries and they tested ok. I thought it was the batteries too. That’s not the problem. Thanks

[82eye]

try another cluster. the circuit board has likely failed.

edit : make sure the coding plug is seated proper.

[dmw]

Makes sense. Unfortunately I don’t have a spare.

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Makes sense. Unfortunately I don’t have a spare.

[82eye]

Makes sense. Unfortunately I don’t have a spare.

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Makes sense. Unfortunately I don’t have a spare.

see if you can source a spare or test before sending it off / going further.

download a copy of your etm to trace the electrical from here : Index of /Manuals/BMW (wedophones.com)
get one before gone. you can trace all the inputs and fail points etc.

[Mikealwa]

I have to hit the top of my dash like the fonz every drive to get it to get off cold...also my tack and speedo didn't work for a year of driving and after I drove the car more and more they just started working. Don't know if that's a solution, but might give you hope.

[dmw]

FE548433-01BD-4827-90E1-17967551B651.jpg

Hopefully this picture uploads. I found a spot on the service indicator circuit board that was damaged. One of the screws that holds the two cluster pieces together was screwed in too far. Is that my issue?

[richardodn]

That is your issue for the tach and mpg as they are both driven from the SI board. The wrong screw was used. This kind of damage is not uncommon. Your temp gauge is likely the ground nut on the back where it attaches to the main board. Snug those and the fuel gauge ones up before you reinstall the cluster.

Also read this tech article https://bavrest.com/technical-articles.html

[dmw]

That is your issue for the tach and mpg as they are both driven from the SI board. The wrong screw was used. This kind of damage is not uncommon. Your temp gauge is likely the ground nut on the back where it attaches to the main board. Snug those and the fuel gauge ones up before you reinstall the cluster.

Also read this tech article https://bavrest.com/technical-articles.html

So I assume I need a new SI board. Correct?

[82eye]

FE548433-01BD-4827-90E1-17967551B651.jpg

Hopefully this picture uploads. I found a spot on the service indicator circuit board that was damaged. One of the screws that holds the two cluster pieces together was screwed in too far. Is that my issue?

oh no. that kills a lot of boards. guys remove the cluster than put the screws back in the wrong spots. nothing to do now but get a new cluster or board.

[richardodn]

So I assume I need a new SI board. Correct?

It depends on how handy you are at repairing traces on a circuit board.

[YoungSensei]

You could theoretically clean up those 2 damaged traces and bridge them each over with wire, thus restoring their connectivity. Specialty electronics repair shops may be willing to take on the repair for a reasonable price. I've seen similar repairs done in handheld electronics and game consoles.

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I actually have a spare cluster and am in Kansas City also, if you wanted to buy one. Do you have an e or i?

[richardodn]

If you're looking at having someone else do a repair/replace of the SI board, I'd suggest contacting https://bavrest.com/si-boards.html