OBC malfunction - a tricky one

[Brianmoooore]

Your OBC seems to be acting like the permanent live supply is being interrupted momentarily. That would account for both the time resetting, and the gong sounding the ice warning.
Does giving things a could thump cause it to loose settings or flicker? Do a wriggle test on the wiring.
Any permanent live on an E30 should have red as its main colour, and the only one between the instrument cluster yellow connector and the OBC is a red/white one.

[Royalratch]

I haven't really whacked it to test but it does this quite frequently now, not lasting more than 5 minutes.

Perhaps it's getting confused because it has a different coding plug to the one in the clocks and just resets?

It works flawlessly and cosmetically is very clean - I'm sure it's not damaged.

But who knows...

[Speedtouch]

TBH, I briefly used the speed limit gong on my 325iSE (set to 30mph) after fitting a new gong because the old one was duff and it became very annoying very rapidly once the novelty had worn off!

[Royalratch]

Probably the least useful function on there.

I find external temp and average speed useful. Range is cool too if it's accurate.

[Speedtouch]

I became obsessed with monitoring the M/G on mine!

[Brianmoooore]

Probably the least useful function on there.

I find external temp and average speed useful. Range is cool too if it's accurate.

Speed limit is set to 80MPH on my wife's touring. It is spot on accurate (against GPS), and is effective in curbing her 'enthusiasm' on fast roads, and not attracting plod.

[Royalratch]

There's a thread on here that shows you how to calibrate the OBC so that it very accurately reflects how much fuel is left in your tank and thus the correct range. The factory setting is way off apparently.

[AndrewL]

Factory setting works fine on mine - accurate on range to within approx 5 miles although display blanks at 10ish.

[Royalratch]

You talking about remaining fuel right?

Did you retrofit yours?

[AndrewL]

Yes, talking range in miles remaining.

Retrofitted to a 325 cab that had never had one.

[AndrewL]

I don't want to upset orangecurrie who seems a very scholarly gent with his pipe —a and he's not far away in West Sussex so might come round and put the boot in, but the innards of the OBC do disassemble rather neatly and easily. However you can only replace the keys with the front panel intact as a unit.

To disassemble:

Peel the part-number sticker on the side back as far as the join in the case. Take out the coding plug and the light tray and undo the two screws on the back so you can gently lever to back off. There are two plastic clips each on the top and bottom which are retaining it on lugs. Doesn't really matter if you break some of these anyway.

If you look carefully at the insides you can see that the green clump of circuit boards simply pulls off the front panel. There are long pins projecting from the panel which make connections into blue sockets on the boards but there are no mechanical fixing which hold it together once the back cover if off. Simply grasp the boards and pull the whole thing slowly apart.

Then youâ€Ëall be able to access and undo the 6 screws which hold the display down. This comes apart in the same way as a 1980s calculator for anyone who's older than 22 around here. The window can be cleaned and reassembled. The parts (display, mask and backlight) are keyed and won't go in the wrong way round. Incidentally the display is glass and doesn't look as if it's coated which, had I known before, might have led me to be more vigorous in cleaning the front.

It doesn't look as if you can get the keypad out of the front panel without breaking something.

All this may be useful to someone who has non-working electronics (or display) but a clean keypad. In this way you can swap and rebuild the electronics, the display and the keypad as integral units.