Rebuilding Corsa key fob

I have a Corsa keyfob which the rubber is perished and the push buttons
are shagged but electrically it is fine.

Looking on ebay I can get a spare fob for £5-10 so what I intend doing
is unsoldering the
push buttons from the new pcb and fitting then to the old fob along
with the new rubber parts
to avoid the need for programming.

The alternative idea I was playing with was removing the old eeprom and
fitting that in the new fob.
I suspect that the white chip is the eeprom and the black chip the
processor. This would also save any need to programme the fob.

Has anyone been down this road and can point me in the directions of
any problems that I might come across such as the buttons being glued
on the pcb or anything like that (I don't think they are)?

Thanks

 

yep should be ok
i'd be inclined though to give the old buttons a good dose of switch cleaner
[not wd40!!]
and resolder the joints too
as most people think that make remotes work better by pushing harder &
harder till is breaks the joints.
bit like shouting on the phone really..........

mike



I have a Corsa keyfob which the rubber is perished and the push buttons
are shagged but electrically it is fine.

Looking on ebay I can get a spare fob for £5-10 so what I intend doing
is unsoldering the
push buttons from the new pcb and fitting then to the old fob along
with the new rubber parts
to avoid the need for programming.

The alternative idea I was playing with was removing the old eeprom and
fitting that in the new fob.
I suspect that the white chip is the eeprom and the black chip the
processor. This would also save any need to programme the fob.

Has anyone been down this road and can point me in the directions of
any problems that I might come across such as the buttons being glued
on the pcb or anything like that (I don't think they are)?

Thanks

 

Why do people do this? They seem to have a lot of misplaced faith in
WD40! It is TERRIBLE stuff to put anywhere near electrics!!

The ONLY cleaner I would attempt to use is isopropyl alcohol although
really I don't think ANY liquid should be used unless it is a last
ditch attempt. The contacts of these buttons SHOULD be self cleaning
from friction of the plates in them.

Unfortunately the WD40 fan club seem to have beat me to this previously
and the rubber has disintegrated along with the buttons which are
partly rubber but the pcb is clean and functioning which is why I am
going to attempt the rebuild.

Interestingly the fob works fine as an ignition key without the fob
attached (i.e. the fob only controlls the CL) so I am not sure how
using the diagnostic adapter to programme the fob works anyway.

If a rebuild of the buttons is fairly straightforward then maybe it
might just be worthwhile offering a service, especially if the parts
could be sourced on their own. I suspect that they MIGHT be available
as a standard Siemens part.

Thanks for comments.

 

A hand held device is pluged into the diagnostic adapter socket and is used
to tell the cars computer to accept the 'new' key fob code. The keys code
stays the same. I know 'coz Vauxhall charged me £20 to do it, and it took
ooh maybe 20 seconds max.

 

It will, because the transponder that tells the car that the correct key is
inserted glued to the key shaft and is not powered. So you can start the
car without the battery in the key fob.

(i.e. the fob only controlls the CL) so I am not sure how

 

Thanks I wasn't very clear. I was saying that I don't understand how
the eeprom is read
and programmed and that it must be done over the rf link itself as
there is no direct
connection.

I mentioned this as not having a suitable rf set up to play with I am
also toying with the idea of stitching a few thin wires on and
attempting to read the eeprom and (what I assume is a )cpu with a pc.
The ignition transponder has its own code which the car must be
programmed to accept but I suspect that the remote part is the other
way around and is programmed FROM the car?

Just MAYBE cloning the remote part MIGHT be possible if this is
correct? I'm jumping the gun though.

I'd be very grateful if anyone who knows what they are doing in this
area could give me any pointers to URLs?

 

the key is linked to the immobiliser circuit
it is inductively powered (see the coil around the ignition barrel)#
the ECU is progged with the key number.

the alarm fobs [depending upon age] are the other way around as you guessed.

the same 'series' can be progged from the car when things are set correctly.

now these push buttons
they are very common
in lots of devices
and are often the same
infact [sad] i lookout for these at boot fairs they are in old tv/? remotes
they are also in maplin / or cpc
i use them often

you can quite easily 'clone' the eeproms [and all other proggable chips]
using boards available ebay and the fly lead clip

TBH its not worth it

you should find that by changing the tits it will work.

does it work manually? if you s/c the pins

mike

Thanks I wasn't very clear. I was saying that I don't understand how
the eeprom is read
and programmed and that it must be done over the rf link itself as
there is no direct
connection.

I mentioned this as not having a suitable rf set up to play with I am
also toying with the idea of stitching a few thin wires on and
attempting to read the eeprom and (what I assume is a )cpu with a pc.
The ignition transponder has its own code which the car must be
programmed to accept but I suspect that the remote part is the other
way around and is programmed FROM the car?

Just MAYBE cloning the remote part MIGHT be possible if this is
correct? I'm jumping the gun though.

I'd be very grateful if anyone who knows what they are doing in this
area could give me any pointers to URLs?

 

I'm getting SOMEWHERE slowly!.......... Any help welcome.

---------------------------------------------------------------

Two chips in Corsa/Siemens keyfob

EPCOS R750 SRPO

R750 seems to give fHz (433.9) is probably a resonator

http://www.epcos.com/web/generator/...__en.pdf;/Produktuebersicht_2006_Internet.pdf

Other chip has yet to source.

To29 M44C890C IM238006

 

44c890 is a static eeprom

yep the r750 is a ceramic resonator

you can clone the 44c890 code by using.
Willem EPROM Programmer



mike