As I stumble through an uphill learning experience with a TF this topic is of interest. Has it been possible to find a means to renew the battery in this horn please? Also where do I find this horn and what is involved in removing it.
I ask because we think that the car alarm that woke us up at 4 AM two nights ago might have been our locked up TF in the locked garage. By the time I had got outside to check which car it was the horn had stopped. So all we have to go on was a slightly distant horn sound that was neither strident or with a deep note, but it had some similarities with the sound one hears when initiating the horn test prior to coding in key fobs using pscan.
I'm no expert but I can say with confidence that my 2004 MG TF with a Pektron system uses the vehicle horn as its alarm sounder. I've set it off enough times whilst trying to make the wretched EKA work. It is entirely possible that this could be a change from standard, carried out by a previous owner, I suppose.Well, what I can see fron electric diagrams mk1 MG TFs which have Lucas alarm system DO NOT have BBUS unit, but use horns.
Mk2 MG TFs which have Pektron alarm system DO have BBUS unit and use it instead of horns.