Yes...the old SI board question

[vonfrost]

Ok, so my tach,fuel economy gauge & clock died. I did some research and everyone points to the batteries on the SI board. No problem i pull the cluster out and had the Sanyo lithium batteries replaced. Put it all back to together re-set the inspection lights....however my tach,fuel economy gauge & clock still do not work?

Now my question is what do i look for now?

Thanks for any help or push in the right direction.

[Adrian_Visser]

did the batteries leak onto the circuit board? you may need to replace the whole SI circuit board, the reason shit goes haywire is the electrolyte corrodes the printed circuits.

[vonfrost]

No leaks from the sanyo batteries, the board looks brand new. The green,yellow & red lights work on the board.

I picked up a spare cluster but the batteries are also dead. I may just swap out the whole tac/fuel economy gauge and spray all the contacts with Electrical contact cleaner...but i don't think that is the problem?

[vonfrost]

Ok,

So i just tried a working cluster...but i still have the same problem of a non- working tach,fuel economy gauge & clock. What else can i look into? the wiring harness? I don't really want to get into that....how much work would it be to wire in a after market tach?

[jlevie]

I think you have two separate problems. One with the tach & econometer signals to the cluster and another problem with the clock. The problem with the cluster sounds like the relevant signals aren't reaching the cluster, either from a wiring fault or a problem with the DME. The problem with the clock could be no power to the clock or a bad clock.

[vonfrost]

Thanks for the reply, I tested the clock with a working one from my friends car..... looks like i have a wiring problem? i just thought it was all together because the cluster/clock died at the same time. Looks like it'll be broke for good....I'm not very good at searching for wiring problems.

[AlarmedBread]

did you check the fuses?

[Quadrajet]

I was thinking what AB said. I just had my fuse blow this morning before I went to work. Mine is so intermittent that the fuse won't blow for 2 months..then poof. Very frustrating.

[vonfrost]

did you check the fuses?

First thing I did, once I verified that all my fuses where good I went ahead and replaced the SI board batteries.
This problem is starting to piss me off! :hitler:
I'll look more into it on the weekend, I would really like to have my tach working again.

Thanks for the input.

edit-
Could the speed pickup sensor in my diff be the culprit? I can’t see that being the problem for the tach?

[jlevie]

The speed sensor has no affect on the tach.

[vonfrost]

The speed sensor has no affect on the tach.

I didn't think the rear diff speed sensor had anything to do with the tac.
I tried my cluster in my friends car today, works great! so i now know that it's a wiring or some other strange issue with my car.

What else can i check?

[bimmerboy12]

check to see if you have power at the fuse. That will at least tell you if the current break is before or after the fusebox. Don't give up, electrical issues in these cars are very intimidating but usually a very simple fix like a corroded connection or something.

[vonfrost]

I have power at the fuse(s).

I am thinking about installing a aftermarket tach, what color wire would be the the rpm signal wire on the Ignition Coil? the red wire?

EDIT-

I also notice that the interior, trunk and reverse lights are not working...along with the tach & clock not working.