I have a 1988 944 NA, 61000 miles, the service light comes, gauges (oil pressure, temp and alt.) begin malfunctioning, however the car continues to run fine until it's turned off and you go to restart it (acts as if the battery is drained). When I disconnect the negative battery cable and reconnect it the car starts normal, gauges are fine and the service light is off (this process seems to act as reset????) until the cycle begins again after being driven again for approximately 5 to 20 mins.. Has anyone experienced this? Suggestions appreciated. Thanks.

 

Maybe the battery has a bad connection? Closely inspect both battery cable terminals, the ground cable to the clutch bellhousing, the power cables at the starter, and the power cable at the back of the alternator. Make sure there's no corrosion, and just clean metal contact.

Also, one thing I just learned after using it wrong for years: dielectric grease should not be used on electrical contact surfaces, because it is an insulator. It should only be smeared on the outside as a corrosion barrier.