Hi all, I have a question about my '75 W200 with the 5.9. There is some kind of sensor/resistor thingy mounted on the drivers side fender up near the hood hinge. Its looks like a chunk a metal a few inches square. There are 2 wires connected to it with a square black plug. It must have something to do with the ignition coil because when it's unplugged the truck gets no spark.

The problem is that when the truck is running that little metal box gets EXTREMELY hot. I'm assuming thats not normal, right? Can someone tell me what it is so I can buy a new one? Thanks.

 

sounds like the ballast resistor. it is normal for it to get hot while the truck is running.

 

I cleaned up a spot on the firewall and mounted mine with some thermal paste stuff. Seemed to help it run cooler.