It is a little 4 wire (I think it was still a 4 wire in 94) connector by the battery. It might have a black rubber cap on the end of it, or the cap might be loose. IIRC, you short the bottom 2 wires, when holding the plug with the tab up. It should tell you on the sticker under the hood, which wires to short for sure.
I set my samurais at 10* BTDC. No pinging on regular 87 grade gas.