Reset Oil Light: Lost Speedo, Odo, MPG Meter

[Vivek]

So I did the oil reset light procedure described here, as well as numerous other places, by sticking a paperclip in ports 7&19 and turning the key to position two. The oil light immediately went off, but I waited for over half a minute and the inspection light didn't turn off, so I just took out the key, put the port thing back on, and left it.

Fast forward two hours. I'm driving the car and notice that the speedo is at zero. Subsequently, the odometer doesn't turn, and the MPG meter under the tach is at 0 when pressing the gas, and goes to 40 when you let off. What the hell happened? I'm as sure as I can be that I used the right ports, and I've never heard of anyone having this issue before. Any help?

[Vivek]

Paging GAS...please help. All fuses are good. There also doesn't seem to be any power going to the head unit ares (there isn't one in, but the wires were getting power before this, but not today).

[dnguyen1963]

Your SI board just went south.

[Vivek]

That's what I feared. Will I have to replace the cluster (I hope to god not)? Actually, I think it may be something else. Why else would there not be power going to the head unit?

[BergerNJ]

if theirs no speed reading you wont get any mpg readings......I sometimes drive solely by rpm.

[Vivek]

Yes, I think that the other two problems are based on the fact that the speedo's not working. It doesn't effect drivability at all (speedo is off like 20% anyways because of small tires and all e30's are optimistic), but i'd like to get it fixed asap because of the mileage not counting. It's my dad's DD, so it'll get like 300 miles a week.

[nando]

the SI board does not control the speedo. if your speedo is bad, something else has gone wrong.

the SI board controls the tach and MPG gauge. the speedo also inputs into the MPG gauge. if your speedo goes out, so will the MPG gauge, even if the SI board is good.

[Vivek]

Bump...still an issue. Do you guys think disconnecting the battery for 10 min will help anything? The car has no radio so it's really nothing at all to lose.

[bowtie2bimmer]

Its common to f something up while doing this (I've done it 3 times with no issue) but if you have a buddy with a good si board I'd swap em to see if it works. I replaced my odo gears and when I reinstalled everything the tack, obc, mpg gauge etc didn't work. Swapped in a known good and all was well.

[Vivek]

the SI board does not control the speedo. if your speedo is bad, something else has gone wrong.

the SI board controls the tach and MPG gauge. the speedo also inputs into the MPG gauge. if your speedo goes out, so will the MPG gauge, even if the SI board is good.

What would that something be?



I have a feeling it's not the SI board if the SI board doesn't control the speedo, because the tach, temp gauge, and fuel gauge work fine. And i'm not sure of anyone who has a good SI board laying around, but I'm sure I could find someone.

[bowtie2bimmer]

Even a buddy with one in his car that is good. I can yank out the gauge cluster in <5min so its no problem to pull a buddies.

A friend of mine with his m10 model had a similar issue (no mpg, tack) but his speedo "worked" just 30mph off. replace the si and all worked fine again

[dnguyen1963]

A bad SI board can do some real funky thing to the whole cluster even though the speedo is not supposed to be under its control.

[nando]

it would have to be a hard short (ie completely fried). the function of the speedo is completely independent - although it does supply a VSS signal to the SI board. basically, the SI board would have to be shorting 12v to the signal wire from the speedo PCB.

it's probably worth checking the wires and connector at the diff - it could just be a coincidence. or perhaps you actually did totally fry the SI board.

[dnguyen1963]

Yeah, you can't believe how much damage 2 leaky NiCd can do to the SI board.

[Riley103]

A bad SI board can do some real funky thing to the whole cluster even though the speedo is not supposed to be under its control.

I also think so.