SI board batteries removed, now tach and temp works

[jayuuey]

Just picked up a 87 325e and the tach and temp gauge was not working. I pulled the SI board to find the varta nicd batteries corroded. I removed them and was going to solder a remote aa battery back to run regular button top nicad batteries from radioshack. But I found 3 pin nicad replacements on ebay so i held off and just reinstalled the cluster with no batteries so i can move the car. Upon started up the gauges twitched a little bit. A few days later, I start the car and and then the tach and temp came to life! whether or not its accurate, i don't know.

Has anyone experienced this? Pretty cool now the tach works, just found out the car revs well over 5k haha.

[efficient]

I think you need the batteries because I've read that your car won't charge.

[Gregs///M]

The alternator will still charge with the SI board out, but cluster in. I have seen a few SI boards work without the batteries such that they pass through the tach and temp signals. However, your OBC should not work without the SI board.

But without the SI board batteries, you might find in the long term, your temp, tach, and MPG gauges might work intermittently.

[jrobie79]

I think you need the batteries because I've read that your car won't charge.

my m42 powered e30 ran for 2 weeks without a cluster...never needed to jump it once, I doubt the battery stored enough power to start it multiple times a day for 2 weeks without the alternator charging it. So in my experience the cluster out caused no charging issues