I prefer a safety pin... hook yer probe on the loop in the wire, and wrap a piece of eelektrikal tape around the "latch" part to insulate it, and give you a place to hold the probe.

But, if you can't see any metal when you look inside, then you might have to pierce the insulation, but like Wayne sed, it'll seal back up, but a lil dab of RTV is a good idea. (IF you can even find the hole the pin made!)

C/YA!
Jeff
'88 Trooper
2DR LWB 4ZE1 5SP
bone stock DD