Hello Helen and welcome to the forum.
It' s great to have a technical problem to consider so here I go:-
Handbrake warning light.
I' m on my second 944 and neither of them had/have working handbrake warning lights.
As Paull noted, there is a switch (the same as the door courtesy light switch) mounted under the handbrake wich is opened by the handbrake presseing down onto it. On my Lux, this switch was mounted on a particularly nasty pressed metal braket which bent. As a result the switch wouldn' t press on the underside of the handbrake lever, as it should, and the light stayed on constantly. To remedy this, the previous owner disconnected one of the wires from the switch.
I don' t know why it doesn' t work on my current 944, I haven' t realy looked.
In summary, the operation is fairly simple so try the following tests:-
a) Is there power getting to the switch?
b) Does the switch work properly if you fiddle with it?
c) Is the switch being depressed by the handbreak lever?
Self Raising Tailgate
There is significant debate as to wether the tailgate raises when you press the button or not. Some say it does, some say it does but only when you shut the door, some say it doesn' t.
First test - as Paul noted - do you hear a wirring sound from the motor in the boot?
No wirring, motor not working so you have an electrical fault.
Second test - If you unlock the boot with the key, does the tailgate rise by it' s self. If the tailgate is slow or doesn' t rise then the first port of call is new tailgate struts. These aren' t that expensive (in Porsche terms at least).
You indicate that sometimes your tailgate works. This could be that the struts are tired and could do with replacing. As they are presurised gas they work better when they are hot. Does the tailgate work better in hot weather?
Perhaps more quetsions than answers, but something to be going on with.
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