Trying to get to the bottom of my dead instrument cluster, I read various posts regarding the "hard reset". I am familiar with the concept from ownership of an old 7 series BMW, whereby, both battery terminals were disconnected and hooked togeher, for about 15 minutes. However, posts on here suggest that the negative - lead should be disconnected from the battery and then held onto the positive + battery terminal, with the ignition switched off. Is this correct? A definite answer please, from someone who has actually done this, without frying anything in the process. I am reluctant to send power to earth/ground using this method and want to be sure I have it right. Thanks in advance.

 

I use the "disconnect both cables" method. No problems.

Cheers
DD

 

Both methods achieve the same thing. If nothing is connected to the negative terminal of the battery, the positive terminal can't send any power anywhere.

 

It doesnt matter and its only seconds not minutes. Youre just discharging capacitors in modules which erases volatile memory.

 

Thanks for the replies folks. I will have a go at that on Monday when I get back to the car. Running out of options fast!

 

And , of course, if the trunk is open and the light is on, then you are almost SURE of discharging the caps without shorting the cables together. But is make you feel better to do it!

 

Well, I tried the hard reset as discussed ( Touch negative battery cable to positive battery trminal ) in an effort to get to the bottom of a dead instrument cluster. The reset didn't help matters, except that where my mileage would have been showing, there were just a series of "dashes". The mileage has reappeared, but is now showing at approximately only half of what the actual mileage is!

What gives?? Any thoughts appreciated.

 

Well, as a first rather obvious GUESS, I would say the instrument cluster might have crapped out. I have never seen the dashes, but then I have never been looking at the cluster as I reconnected the battery. And I am sure the divide the mileage in half thing is not a common occurance or someone would have mentioned it before. If the module wa dying, your symptoms could surely be the result.

 

FWIW, I get the dashes whenever I reconnect the battery....but never had the problem of the recorded mileage changing


Cheers
DD

 

Silly question, but it's not just defaulted to miles rather than km has it?!

 

I bet Ziggy has it!

 

Doesn't necessarily help much though - if the switch is still in the km position then something ain't right! But wouldn't hurt to try switching it to see what happens...

 

Not a model I know anything about but is this cluster in the range with a known (fixable) solder joint problem?

 

Not such a silly question, but my "mileage" was showing as Miles, so, if it switched, it would be showing Kms now, which would be showing more, not less. Thanks for all the replies. I have been studying wiring diagrams and am working my way through that particular minefield. I have yet to remove the instrument cluster to check the connector at the back and the earth. If the instruent cluster has died, I have one in a donor car, but will have to get the mileage reset, yes? The donor car has 165k on it as opposed to 97k on my daily driver!

Thanks again and watch this space.

 

I suspect there is no method to reset the mileage. You might be able to dig the memry chip out of the old one, but that is extremely risky in that it would seem the memory might very well be the problem. Goos luck.

 

I do remember reading somewhere about dash/instrument clusters being swapped and having the mileage reset at a mail dealer. But I don't know if it will come to that, as I noticed today that the mileage doesn't change. It's still showing the same mileage since the reset, so maybe it's not a permanent thing? I will know better when I go hunting tomorrow.

I intend to check the ignition swich/ wiring and connector beneath the steering column shroud, as an additional (new) situation has developed. The car tends to cut out when driving, if I brake any way hard at all. I still have no radio, which seems to be where my problem started, when it just froze up and refused to switch off, even with the ignition off and the key removed. Disconnecting the negative battery lead sorted that out, but left me with a dead dash. So, I supposer another look see at the relays wouldn't go astray. I also switched between miles and Kms with no effect.

Thanks again for the input, a problem isn't so bad with others chipping in!

Updates will follow.

 

sogood .... I can't offer any help with your problem but I just had to comment on something that you said/typed.
You typed .... Thanks again for the input, a problem isn't so bad with others chipping in!

When I ask for help with a tricky problem, it feels just like a dozen or more guys are leaning over my shoulder as I tinker with the engine. Not only stroking their own chins a d telling me what to do but getting info and hints from each other at the same time as well. It's like magic at times.