Boy did I screw up! I reversed the positive and negative when connecting the battery.The car is a 1984 300d.I noticed smoke coming from the red wires and quickly disconnected the battery.
After connecting it correctly the glow plugs work,engine starts and the oil pressure gauge functions.Nothing else works,no lights,radio,wipers etc..
I peeled open the rubber covering and see that two red wires are damaged.
Kind of burned to put it mildly.Can someone please advise me how to fix this?