Baffled by the Technology.....

[Xantianut]

Ay up!!!!

Nowt new here eh?

Well, a lumpy parcel arrived today containing the replacement door locks, steering lock, transponder ring, ECU, fuse box and, interestingly, the passenger airbag switch.

Now, I know the fuse box is not computerised so no worries there. I was wondering what would happen if I switched the ECUs over? It is the same part No as the existing unit but I have read horror stories about the BSI not talking to a replacement and also refusing to recognize the original when refitted. Any advice? Or is the answer leave well alone? It would be nice to have one key for everything, but, if this causes problems, wil retain the 2 key system.

The other question Imhave is regarding programming the fobs. Their batteries are in rude health, returning just over 3v on my multimeter. I've read several different accounts of which buttons to push and for how long and this has given me a migraine!!! So, in terms that a Technophobe can understand, how should I do this? Or is the answer impossible to program a 2nd hand fob to the ECU?

Please help......

[Northern_Mike]

It is impossible to program a 2nd hand fob on a C5 MK1

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[citroenxm]

Its impossible without a lexia!!

You can only swap an ecu as long as you have the matching bsi to go with it and also matching keys as a whole matching kit if you don't have a lexia. Without a lexia with a c5 your rather stuffed its needed for everything

There is a section in lexia you can get it to match up keys. You need them all to hand though as it will do then one at a time.

[Northern_Mike]

Its impossible without a lexia!!

You cannot match a secondhand key fob to another C5 with or without a Lexia, unlike Xantia.

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[addo]

That's been my experience too. Once they stopped using the separate chip units and went to an integrated board, the immobiliser transponder became a "one shot" item.

[Xantianut]

Thanks, chaps.

I'll just use the locks then until I get myself a Lexia.

[Xantianut]

RHS lock fitted and amazingly I didn't need an extra joint in my forearm!

Now for the LHS......

[Xantianut]

Ay up!

OK - locks now fitted.

So, with Lexia, it is possible to program the plipper to the car, is it?

And, as for the transponder, where does the chip lurk and how do I get to it? I can't work out either!

[citroenxm]

The chip is in the large plastic part of the blade. Remove the key blade from the plipper and one of the sides will come off and the chip is in there.

[Xantianut]

Thanks for that.

Transponder chip located and now thinking up my next move here. How easy is it to program the car to a virgin transponder chip? I am wondering about doing a transponder by pass with all that entails but the insurance issues suggest it's a bad idea.

The chips are out there and cheap enough, about £4 each. Plenty of time before I get a Lexia.

Any ideas, folks? I'm all at sea with computers.