Volvo Owners Club Forum - "Immobiliser- Refer To Manual"...familiar??

This problem has driven me to distraction for the last few months, and after a few breakdowns and recoveries I had lost faith completely in my car to go anywhere in it, and getting in it to it to see if it would start was a hold your breath moment.
The problem was that that, seemingly for no reason I had the intermittent reading above "Immobiliser See Manual"-on IgnitionII, and on ignition III I would get "Brake Failure Stop Safely"... There was nothing on the key at all. No breakdown mechanic could sort it out and I had a new battery on their recommendation thinking this was the fault. No it wasnt..and again today I got stuck on the drive in freezing weather.

BUT-joy of joys!- Today I found the answer myself! AND even better it took just 30 seconds tool-free time to sort!

I had read a lot of posts on forums and elsewhere, and it seems to me that it narrows down to just THREE possibilities...I tried the first 2 without success but will list them in case they are yours:

1) The ring antenna behind the ignition key entry has lost connection with your key chip. To sort this press the door lock on the fob on and off between 5 and 10 times -this may connect them. If not, try holding the key on Ign III and tapping firmly the head of the key..... It is common for some oxidisation of the antenna terminals to cause the problem and this may just free up the clag and connect again.

2) Starter motor trigger cable. This apparently is also likely to corrode and especially at the terminal connections- a clean up can resolve. This also results in the messages above surprisingly

3) My final answer!- the 2 connectors to the ECM become jolted loose or even dislodged by feet! If you look right at the back of the passenger side footwell (move the carpet out of the way) you will see just 2 multi cabled entries into the ECM which is located there.
These apparently are easily loosened and they are on like a simple buckle lever securing system. Quite simply, check that this is clipped in on both the cables- in fact its worth, as I did, clipping and unclipping several times so as to ensure proper connection. There is actually a video on Youtube where I got this from, but its so simple you wont need it Im sure.
The clues for me that this was MY problem was that the windscreen wipers would go mental, the indicators similar, and the specific reference to the brake failure. Also I had weird readings from the temperature readout. I have also been having my "Return Home" headlights stay on and off depending how they felt after turning off-maybe this has resolved too I hope? lol

So...good luck! Hope this manages to help out at least one person who also must have suffered the sheer frustration I have experienced on this..let me know if it has!