I have a 98 XK8 where the oil pressure gauge just went off completely to the right. I have no oil pressure light warning and I checked the oil in the engine, which is fine. I replaced the gauge but the same happened with the new gauge, simply no movement in the gauge at all. Any ideas?

 

See figure 8.1 here: http://jagrepair.com/images/AutoRepa.../jagxk1998.pdf on the upper right.

Check the 4 wires labeled 'oil pressure' between the main instrument cluster and the minor 3-gauge cluster for an open or a connector pin that may have fallen out.

If all is OK with the wiring, then the problem may be the main instrument cluster that provides the signals that move the stepper motor in the gauge.

BTW, this is a 'fake' gauge, an only moves to 0 and to mid-scale, so it really does not provide any more information than the red idiot light.