There’s nothing in the manual about this light, and nobody seems to even know what it’s called, which makes it hard to explain to people what the problem is. Part of the problem is that it flashes all the time, whether the car is locked or unlocked, and when it’s being driven. That’s a problem because it’s clearly visible at night if you stand in front of the car and, at least in the UK, it’s an offence against the lighting regulations for a motor vehicle to show a red light to the front. That makes it technically illegal to drive.
The digital operations were converted into a Boolean logic map, and subsequently implemented using diodes and SPDT switching relays. The advantages of this approach are manifold, as standard automotive five-pin micro relays are readily available at any auto-shop and the diode assemblies used to create ‘OR’ gates, although custom, are small, cheap, easy to carry as spares, and are fitted to plugs, making the LRU of the unit a fuse, relay, or a diode gate, any of which can be replaced in a few moments without tools as a roadside fix.
My VW Transporter T25 DG series engine had started developing white and green residue, especially underneath and around the black rubber gaskets either side of the cylinder heads. At some point it also began using water.
To fix it you’ll have to take the cylinder heads off and do some work on them. With a bit of effort, and if you’re careful, you can do this with the engine in situ.