Window Glass Dropping

The door glass on the 600 (and indeed the 570) has an absolute mind of it's own sometimes. However, all of the behaviours it exhibits can be traced to one of these 3 core features/reasons:

Quirk: Glass drops to 50% despite being asked to close

When: Often this happens either while driving, or while closing the door and it's trying to go up the last inch by itself. When happens then is it opens 50% automatically without you asking it to.

Why: This happens because the door controller thinks something is pushing back on the glass. It is a safety feature, to stop you beheading your children, or shortening your fingers. When stationary this will be due to the resistance of the glass moving, either in the runners, or as it pushes against the seal of the door. When driving, it's literally just the fact the car was hitting a bump at the time and the mass/inertia of the glass caused it to exceed the load-limit threshold on the motor.

How to avoid/fix: Ultimately if this happens all the time, then it needs the door controller to be re-calibrated (via MDS). Be aware though, that if this is mostly triggered by the door being closed, then this can also be a sign that the door hinge (or roof panel itself) is out of alignment. You can also check and lube/refresh the rubber glass seals at the top of the door, it can be enough to get them flexing again and they then accept the glass arriving a bit easier. Worst cage, the door hinge is cracked which has screwed up the alignment - unfortunately this is very common.

Quirk: Glass drops only 10%

When: Usually when you are nowhere near the car, and the keys are out of range. Thus, you come back to find it open by suprise.

Why: The glass is opening automatically as part of the battery-low safety feature. The 10% drop is enough to allow you to manually open the door if the battery is completely flat (well, in it's protection mode). This feature does not need the keys to be in range.

How to avoid/fix: When this happens, either your battery sensor module has failed, the battery is genuinely low, or the battery module needs recalibration. Get it on charge to get it out of that mode first and then investigate the battery and it's associated sensor.

Quirk: Glass drops all the way down by itself

When: This one happens only when the keys are in range and you didn't ask the glass to move at all.

Why: If you get this one (and the glass refuses to go back up) then there is water in the door switch itself.

How to avoid/fix: Short-term, leave the door(s) open and up. This will help drain the water out from the rear of the switch. Long-term you have a few options to mitigate it:

1. McLaren did come up with improved switches that have better seals. So first, get those (warranty fix).
2. Avoid power-jet-washing the crap out of the door bars above the switches (this was me, twice).
3. Add a strip of PPF along the upper edge of the door bar. It helps to prevent water getting into the void in the first place.