Indicators don't flash when locking car

[HPsauce]

Originally Posted by HPsauce

I now think that the interior mechanism was probably getting stuck in some interim position

I've found a possible reason for this, though I haven't yet had the latch off the car to verify.

This afternoon, to answer ainars question I had a close look at the spare latch I have - bought from A8parts last week.
I realised that it was rattling and looking closely I could see (through the hole where the release lever is) a piece of plastic moving around apparently not located onto anything.

So I popped the cover open and lifted the microswitch out, to find a small thin curved piece of nylon/plastic about 15mm by 5mm which just fell out.
Looking inside there's a long piece of the same plastic across the latch that is clearly part of the mechanism and which at the very least moves the microswitch lever.
The broken bit appeared to have come from one end, so I'm guessing it would not always work exactly as intended as it was loose and poorly located.
If the switch on my car has similar damage and loose bits in the mechanism that could explain the various failures, including non-detection of closure and not latching at all.

I've dropped A8parts an email with a photo of the parts; presumably they will be able to replace it easily enough.

[HPsauce]

Originally Posted by HPsauce

I've found a possible reason for this, though I haven't yet had the latch off the car to verify.

Possible is now definite.
Just swapped the latch over, actually leaving the existing microswitch in place - it was easier that way and it looked and worked perfectly fine.

The old latch has the same plastic piece inside, though it was made of dark purple-blue plastic not cloudy white nylon. And it was broken in exactly the same way. So, clearly a design weakness.

Looking at the way the latch is mounted it has space around it for water to drain out and the microswitch is "high and dry". So I think I just had the broken plastic problem, the water ingress was a red herring.

So, something for people to look out for. If your boot latch starts misbehaving it could just be a tiny piece of broken plastic inside.
You can, if you look very carefully, actually see the plastic piece by looking at the latch mounted on the car with a torch. If it's not visible it's broken off and you have, or will probably have, a problem. I'll try to post a photo if I can, but that may be difficult, so I'll describe it:

Open the boot, and with a bright light look closely at the latch in the lid, from end-on.
You should just be able to peer down the crack between the plastic latch cover and the boot lid metalwork on what (with the boot open) will be the underside (i.e. inside).
Slightly offset to the offside (towards the lock) you will see a yellowish metal arm (approx. 5mm wide) protruding from a slot in the latch body.
This arm has the lock release cable attached to it, though that won't be visible. If you operate the unlock button (e.g. on your remote) it will move slightly.
Through the open (lock) side of that slot you should see a small piece of plastic extending right across, at a bit of an angle. It also flexes very slightly when the arm moves.
If it's not there or appears loose that's your problem. But it is a very narrow gap so you might not see anything and need to dismantle it to check.

[HPsauce]

Just a (hopefully) final observation if you think you have this problem.
If you take the latch off the car and shake out the broken piece (which mainly causes problems by obstructing the mechanism) it is likely to work OK as long as it's all clean and well-lubricated.

The piece that breaks off is a sort of "return spring" but there is also a metal spring (on the metal release arm) that supplements it indirectly, along with gravity and the spring arm on the microswitch.
So the plastic piece that triggers the microswitch would normally stay in the right place, though it is not as positively located.

[ainarssems]

Well I found a fault on mine, it's the bonnet micro switch. £5.46 from dealer +£3.96 for rubber grommet. Will need to add to shopping list for next time I visit dealer as the only one on e-bay is £24.97 + £2.99 P&P for the used one.