Erratic left turn indicator

[tonyfeline]

Car is 2013 Multispace XTR with 122,000 miles. Operation of left turn indicator is completely erratic, most commonly it gives a few flashs then stops, sometimes works properly, sometimes not at all.  I have even seen the right green arrow warning light operate today when I tried to test the left indicator in a car park, not sure what the orange outside indicators were doing at this point.  Right hand indicator works reliably thus far.

In attempting to narrow down the problem I have replaced all four main indicator bulbs with new. No sign of any corrosion on contacts.  Front earth points near headlights on inner wings are corrosion free. 

That seems to leave as possible causes -

1  Rear earth point - where are they?  I'm guessing under plastic trim cover either side of boot.

2 Side repeater lights on front wings

3 Steering column switch

4 BSI

Has anyone any useful ideas. I'm fairly competent with multimeter.

Thanks

[saskak]

I would venture a guess that the fault lies within the switch or the COM2000 unit. Quite a few metal contacts within the rotary indicator switch and or a cable contact somewhere from the switch. They are very encapsulated these, so difficult to open them, but not impossible. You could probably get a second hand com2000 unit and replace the whole thing, but they have to be the same numbers.

[Gadgetman]

Definitely sounds like the switch.

I have a similar issue with the righthand turns on my old M49.
Sometimes it 'ticks' faster than normal, indicating a poor connection, and if I force the switch a little bit, ticks change to normal rate and blinks happens outside.

[magoo1]

A very similar problem for me,

Started a couple of years back. Had to get to an emergency pharmacist and a blizzard was blowing with plummeting temperatures and the heater blower decided to pack up on all 4 settings. the inside of the car froze and was like that for a day or two. I replaced the blower relay iirc and all working.

However I started to get similar problems to the OP with a few additions dipped headlights choose to not come on and when turning them off they stay on or come back on but eventually they turn off.

The indicator problem is for both left and rich. but left is the worse. indicate right and the left one comes on.

All totally intermittent and no noticeable pattern.

Have suited contact cleaner and as said a sealed unit so didn't achieve much.