Rebuilding Corsa key fob

[No One At All]

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

 

[mikeFNB]

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

 

[No One At All]

yep should be ok
i'd be inclined though to give the old buttons a good dose of switch cleaner [not wd40!!]

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.

 

[Chris (archive)]

yep should be ok
i'd be inclined though to give the old buttons a good dose of switch cleaner [not wd40!!]

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.

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.

 

[Chris (archive)]

yep should be ok
i'd be inclined though to give the old buttons a good dose of switch cleaner [not wd40!!]

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

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

 

[No One At All]

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.

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?

 

[mikeFNB]

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

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.

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?

 

[No One At All]

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

 

[mikeFNB]

44c890 is a static eeprom

yep the r750 is a ceramic resonator

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

mike