Morris Minor Owners Club

I lost all indicators on the Traveller (1970) checked the supply to the flasher unit and had good supply. Nothing out of the flasher unit. I replaced the unit - old one had B P and L on the end new one had X P and L
I made the following bold assumption :

P = P = Stalk warning light (lt Green wire)
B = x = Supply ( Dark Green)
L = L = Lights ( Green Brown trace)

All seemed to work

Did a short run to test another issue and started to notice irratic indicators and strong smell of 'something too hot', on investigation I find the flasher unit is cooked (I opened the can to see - also opened the old one and it is in the same state.)

I assume from the wiring diagram that it's all very simple and the most likely cause that I can think of is a grounded wire to one of the lamps (Bit odd as they all did flash when I checked them??) or rather improbably a bulb with an internal short.

It all got hot enough to make the rubber covers on the spade connectors melt. When I attempt to trace the fault (with a new flasher unit )should I include a temporary inline fuse in the circuit and remove later?

I assume that a check can be made of the circuits by 'injecting' 12v neg (positive earth car) down the various light supply / stalk wires and selecting the side of the car to test with the indicator switch.

Wisdom appreciated and apologies for long post!

Your wiring is correct, ref Workshop Manual P. N44
Try disconnecting the green and green/brown from the flasher unit and connecting them together. Turn the ign. on and try left & right indicators.
They won't flash but should stay on whilst you look for any wiring faults. If you don't find anything wrong then it looks as though you have a couple of dodgy flashers.

That's the advice I would give too - eliminate the flasher unit while you search for the fault. But it should have blown the fuse if there is a short - so inspect the fuse box to see if nails have been fitted inplace of fuses!

I assume that a check can be made of the circuits by 'injecting' 12v neg (positive earth car) down the various light supply / stalk wires and selecting the side of the car to test with the indicator switch.

Rather than wire it directly, you could hotwire the 2 terminals with a 5A fuse. The 2 bulbs on each side should draw less than 5A
2 x 20 =40
40/12 = ~3.4A

Thertefore if one side blows the 5A fuse they will likely be drawing twice (or more) current compared to normal.

Alternatively if you have a volt meter that includes a 10A current measure you could use this - but it won't help the meter if the current is over 10A!

Bulbs can go partial short circuit but my first guess would be a short in the bulb holder itself.

I once fitted a new stop/tail bulb after a major rebuild for the MOT. The tail lights worked and the stop lights worked so I didn't see a problem... The stop and tail were shorted insde the bulb so the stop lights activated the side lights - and I got an MOT fail
I spent an hour checking the wiring before I tried different bulbs