Obc/tach/ not working as well as interior/dash lights.

[sc318]

Okay, I've had my 91, e30 for a little over 2 weeks now, when I first bought the car and for the first few days after I had it everything worked fine..
Then the tach and econometer decided to go out, so I read up about the SI Boards failing. I pulled the cluster, pulled the board, and tested the batteries which both read 3volts. I assume this means that they are fine. The obc was not working from day 1, so I pulled the center console out and it turned out the obc was not even plugged in, so I plugged it in and now it just blinks and doesn't really function properly. My dash/interior/trunk light's also recently went out on me. I've checked all the fuses. I'm a bit at a loss for what to look for next besides start tracing wires, which I'm not looking foward to.

Does anyone have any input as to what else it could be?

And I realize some of these questions have been beat to death, but I just wanted to double check before tracing wire.

[smokemhontas]

My tach and econometer just went out today too.. Fucking sucks

[dashboardmonkey]

Check your fuses again. A visual inspection is just not good enough. Also, the car is 20+ years old. The fuse sockets can be wore out. Replace the fuses with new ones. I have had this exact problem before. Fuses looked fine, and even tested fine. Replaced the fuses and it solved my problem.

[sc318]

Double checked the fuses and replaced some fuses, my dash light/trunk light and OBC are now functioning properly, as well as my speedo/fuel/temp gauges. Still not sign of the tach or econometer working.. Could this be a problem with the board itself? I'm thinking of just ordering one from pelicanparts for peace of mind that its not the board.

[Gregs///M]

Tach and econometer not working are a sure sign the SI board batteries are dead. Just measuring their voltage of 3V is not enough. I repair SI boards and replace batteries all the time for members. I often pull out batteries that measure 3V but their load current is under 100mA's. Which means the battery is dead. Those batteries should have a minimum of 300mA to be even considered good. New batteries have 800-1000mA's.

Also, you have to remove the batteries from the SI board to get a true reading of their voltage and current.

[sc318]

Thank you very much for that info! You were dead on, I was reading about 290mA. Which means they are on their way out..I will replace the batteries. How much do you charge to repair boards/replace batteries?

[Kershaw]

I think he has some boards for sale at $60. Send him a pm. I just redid my SI board batteries, thinking that was the issue. If I did it again, I'd just order from him. Far simpler.

My tach and econo gauge don't work, but my obc is fine. I put the SI board in with the new batteries and my tach still didn't work. I also tested my current batteries and they tested at 3.14v (still on the board.) I didn't check their load current, but I feel it has to be another issue since the new SI board didn't change anything. I also stuck the SI board with new batteries in its original cluster, same deal. Thoughts would be appreciated.

Pic of the new batteries.

[Gregs///M]

Thank you very much for that info! You were dead on, I was reading about 290mA. Which means they are on their way out..I will replace the batteries. How much do you charge to repair boards/replace batteries?

HI, please send me a private message and we can discuss SI battery options/sales. I have many SI boards available.

I think he has some boards for sale at $60. Send him a pm. I just redid my SI board batteries, thinking that was the issue. If I did it again, I'd just order from him. Far simpler.

My tach and econo gauge don't work, but my obc is fine. I put the SI board in with the new batteries and my tach still didn't work. I also tested my current batteries and they tested at 3.14v (still on the board.) I didn't check their load current, but I feel it has to be another issue since the new SI board didn't change anything. I also stuck the SI board with new batteries in its original cluster, same deal. Thoughts would be appreciated.

Pic of the new batteries.[ATTACH]61433[/ATTACH]

Kershaw, in this case there could be two other issues that come to mind.

1. cracked solder joints on the cluster main board. This most often occurs on the pins that the connectors plug into. Those tend to develop cracks from removing the connectors often or years of road vibration.

2. There is no engine signal fed into the cluster. The engine signal comes from the ECM through the black wire on the blue connector (blue connector at cluster). You can start your engine and probe this wire. If you see a pulsating signal, the signal is there and the problem lies with the cluster main board, SI board, or tach itself. However, since both tach and eco do not work together, I would assume the signal input, cluster main board, or SI board. You can also test signal with a multi meter on the AC volts setting, should see 1.5-6V AC. Frequency should increase as RPM increase.

Your SI board and batteries look good. However, make sure got the polarity right. The double pin side should be + and the single pin side should be (-).

[Kershaw]

Thank you for the continued advice.

I should have specified that my econo gauge moves around, but only from 0 to 50+. It doesn't stay in the middle or anywhere else that it should be.

I will check the black wire to see if there is a signal. If there is, I will inspect the board and attempt to remelt any questionable looking solder points.

I'm 99.99% certain the polarity is correct, but now that you said something there is a sliver of doubt. When I installed the new si board, all the service lights went to full green. I'd assume that means everything should be working fine SI battery related. I know one symptom of dead batteries is that you can't reset the service indicators.

[Kershaw]

Huh, I have signal. I watched the frequency increase with rpm. And the signal wire puts out between 2-5 volts AC.

The SI board looked good. No corrosion anywhere. The voltage on the new batteries was a little low, ~3.08, so that was bump charged with a 12v psu to 3.4v.

I'll have to swap clusters with a friend. :/

[Gregs///M]

Huh, I have signal. I watched the frequency increase with rpm. And the signal wire puts out between 2-5 volts AC.

The SI board looked good. No corrosion anywhere. The voltage on the new batteries was a little low, ~3.08, so that was bump charged with a 12v psu to 3.4v.

I'll have to swap clusters with a friend. :/

If you have signal, you probably need your cluster main board to be re-flown with solder. very common problem on our cars.

[Kershaw]

Is that just remelting all the solder points on the board?

[Gregs///M]

Yup, although the proper techniques means adding a tiny bit more solder.

[Kershaw]

Thanks, I'll give it a shot.

I did this once for a friend. Super common problem on a module that controlled the interior electronics on f-bodies. So common it was documented down to 5 solder points. Took a minute to fix! Hopefully i'll have the same luck.

[Kershaw]

i reflowed the solder on half the board (the tach half.) no luck. fuck it. im trying another cluster.