Replacing a motion sensor light switch with five terminals??

[Geoffwhite]

Hi, hoping someone can help with this. I have a bathroom light switch that's a ceiling mounted motion sensor. It's malfunctioning so I bought a replacement, but I've hit a snag.
The existing switch has five terminals, all of which have wires going into them (see photo): green&yellow, grey, brown, then a black cable that links two terminals together, then another black cable.
The replacement motion sensor light switch I bought only has 3 terminals (and I can't find a five terminal one for sale).
Can anyone help?
Thanks!

 

[Spoon]

Can you take a close-up pic of the terminals and just above them. Looks like they have idents on them but they are out of focus.
Do you know that make/model of the existing sensor?

 

[Largey762]

I would assume the brown will be the permanent live, if so, fit that to the outside live in, the black I assume is neutral (if so should be sleeved or taped blue and put in your middle connection) that would leave the grey as your switched live which should have a small sleeve of brown put on before putting into your 3rd connection. Your green/yellow goes into the stand alone earth terminal.

 

[westward10]

I would assume the brown will be the permanent live, if so, fit that to the outside live in, the black I assume is neutral (if so should be sleeved or taped blue and put in your middle connection) that would leave the grey as your switched live which should have a small sleeve of brown put on before putting into your 3rd connection. Your green/yellow goes into the stand alone earth terminal.

Never make assumptions that black would appear to be in an L terminal. As @Spoon says we need a better pic of the terminals.

 

[SparkyChick]

Looking at that picture I would say grey is actually the neutral and the black is the switched live return. The switch in the picture is probably a no volts contact so the short black provides the line input to the switch

 

[farmerspark]

I've fitted a few of these recently, can't remember the brand, as @SparkyChick says the grey is neutral, brown is permanent live, and black is switched live. The short black is a link over to volt free contacts.
There should be a cable clamp fitted ti the visible holes at the top of the picture.

 

[123]

It looks like a Timeguard PIR, albeit poorly installed.

 

[Geoffwhite]

Thanks for all your help!
It is indeed a Timeguard, thanks for identifying it.
I can order a replacement and fit it. But when you say it's poorly installed, can you be more specific please?