the original XK140 flasher/Control relay in my XK140. Recently the fuse (15A) has kept blowing. The indicators are working but not the internal flashing liglit. The fuse seems to blow when the indicators and brake lights are on. So its my belief that the flasher/stop light relay has a short but I am not sure. Before I replace the unit and all the associated wiring connections I am wondering if anyone else has experienced a similar problem and whether it could be the flasher/stoplight relay. It is after all 68years old!
Hopefully the purists won’t shout: I had a similar problem and I had difficulty finding the nice silver Lucas relay. the transistorized units solds by SNG also blew. Otherwise, as you say, I had no wiring issues that I was aware of. Changing to an invisible modern 3-leg relay solved this many kilometers ago.
Welcome Duncan.
Your problem might be in this Lucas DB10 relay. This is what switches the rear bright light filaments between the brake and turn signal functions. You can pop off the cover and clean the contact points inside with sandpaper or a small file.
Otherwise it may be the flasher, although this does not normally operate with only brake lights on, it only works when the turn signals are on. Either a Tung-Sol 241 or 273 will work.
I can’t think of a relay (DB10) failure mode that will blow a fuse . however there might be a stray wire I guess. firstly can you confirm that the indicators work, including the repeaters in the cabin without the brake lights and they are not blowing the fuse? then please confirm the brake lights work (on their own) without blowing the fuse?
lastly has this fail just recently occurred or have you inherited the problem?
I must have been to sleepy to remember this last night, but about 15 or 20 years ago I had a fuse blow every time I signaled a left turn. It was the wires inside the steering column, one was worn through, where they pass over a sharp edge inside when you move the wheel in and out, and it was touching ground inside there. I pulled out the steering column wiring harness, wrapped the place in cloth electricians tape, and put it back. It’s been fine ever since.
Thanks all for your advice. I cleaned the relay points and replaced a tail light bulb (which was working) and cleaned the insides that were a bit rusty. I have checked all the wiring and can find nothing amiss. I put a new 15A fuse in and everything seems to be working so far. Its all very frustrating as I’m not completely sure I have solved the issue as I have found nothing obviously at fault . I have a long drive ahead of me so hopefully will find out if its properly fixed or not. many thanks to all.