Thanks for the guidance notes Colb.
The whole story runs something like this:
I bought the car in 2016 which came with two sets of keys. Needless to say, in my ignorance I used the one on the shiny Z4 keyring most, if not all the time until I was made aware of the importance of using both equally.
By which time the second key would no longer open or lock remotely so I bought a replacement battery, split the case, desoldered the old, put in the new, glued up the casings and….. key would still not work remotely.
So chucked it in a drawer where it lay for two or three years until I recently came across the thread on the Forum.
Which combination of button pressing made everything work in the end, I can not quite recall.
I started with method 1 which didn’t work but to my horror (at the time) disabled the remote action on my master key (shiny keyring).
Method 2 was not successful either.
As with the others, I tried method 3 one more time yesterday and had a partial result at first. The remote on the master still worked and the “back up” (new battery) would unlock but not lock remotely.
So I left it at that as I had a long-ish journey ahead of me (130 miles there & back).
When I arrived home I thought I’d try the back-up to lock the car, and hey presto it did! And it set the alarm as well. So now I have both keys working as they should. Maybe the trip fully charged the back-up battery?
So, to the best of my knowledge, and in my case:
The 15s interval mentioned in method 1 is not needed.
I did insert and turn both keys five times quickly to position 1 and also pressed the lock button three times (quickly) whilst holding the unlock, but did not release both buttons at the same time. Did the same with the second key quickly (within 30s). But, I can’t remember which key I did first.
I was inside the car, doors were locked but the windows were open when I did what turned out to be the successful procedure.
Also think what might have made a difference was turning on the engine to finalize which I don’t think I’d done before. But once again, which key or what order I did this I can’t remember. After countless efforts at trying to get things to work, I’d stopped being as methodical as I should have been but I got there in the end so thanks again.
Robert.