Electrical with intermittent starting issue

[jsf]

Question, I have a 1988 944 NA, 61,000 miles, and when I drive it, somewhere in-between one to twenty minutes of run time the red service light and check oil light comes on, temp gauge goes to the top and jumps around, alternator gauge drops below 12, oil pressure gauge drops from 4.8 to 2.0., if the car is turned off then back on the battery performs as if it is low (cranks as if it is drained). However, if the neg. battery cable is disconnected and then reconnected it resets. After the reset the battery/starting and gauges all perform as normal until the malfunctioning cycle begins again? The engine runs fine mechanically during these malfunctioning episodes and the battery test good. Has anyone experienced this or have any suggestions? Thanks.

[v2rocket_aka944]

Wiggly gauges means faulty ground connection.
Alternatively, reach under the dash and make sure all the connectors to the back of the gauge cluster are on solid.

[dgcantrell]

I agree. Definitely some grounding issues. Check the main ground on the rear of the engine behind the fuel rail. Loosen and retightening them usually fixes most of them. Also check the short ground wire from the negative terminal to the body next to the battery. There is also one large cluster of grounds up under the instrument panel on the left side just under the underside of the fuse panel. 10mm, I believe. Loosen it, wiggle the wires a bit and retighten it.