Having checked out the boards, they are, as far as I can tell, electrically identical for the CL relay, so I decided that as I have another N3 UCH on the way (which has arrived
and is a V5.2 but an A part number, not a B...) that I would go for gold and see if I could get the V5.5 working with the central locking in my car. After looking at the boards, I found that the biggest chip on there is helpfully printed with the version number, so I took a brave pill (aka a bacon and egg sandwich with a cup of tea) and decided to swap the chips over. Officially quite a fiddly job and not one that I would do again in a hurry without the potential of saving quite a few £££ or earning beer. Not only are they difficult to get off the coard without knocking some other component but soldering them back on was a bit of a 'mare and I had to use a scalpel to make sure that none of the contacts were bridged, as it was the only thing small enough.
Anyway, I put the updated UCH in the car and all the functions appear to work fine and more importantly, no clicking relays or flashing lights. Next step, I tried the keys but nothing happened, so I turned on the ignition, pressed the unlock button, had some beeps and flashes on the dash / indicatores and a few variations thereof and hey presto, the car locks and unlocks just fine on the key and the button.
Here are a few ideas as to why this may have worked:
- The chip on my board is configured to my car and if I had clip, I could have reconfigured the V5.5 one (I have a spare to test this theory on).
- The chip firmware / hardware are in fact different and should be swapped over.
- The CL on the cars are different (one has a +/- pulse, one is just a ground for the alarm?).
- It's just French so stop trying to understand it.
So far, I'd say that replacing a UCH for £30 and about an hour of my own time is a bit of a win. We'll ignore the 20+ hours of investigation when I thought it was the 40 way plug... Watch this space for it all to go wrong though, as 10 year old French electrics don't tend to play ball...