Electrical issue
 

I have a 1990 truck with later model carberated 454 engine with electric cooling fans. I was driving the truck and started smelling melting plastic. Then my volt Guage was all over the place. I took the alternator to a rebuild shop. He told me all the diodes were bad and something else was melted and that was what I was smelling. I reinstalled the alternator and no change. Then I disconnected the negative battery cable and truck shut off. If the alternator was working shouldn't the truck continued to run?????? I went back to the shop for a recheck on the alternator and it is making 14 volts. I have tried 3 different batteries and there has been no change.
Any advice????

Re: Electrical issue
 

Using a DVM measure the battery voltage not running and running. The place to start is with accurate measurements.
People will give different opinions on disconnecting the battery with the engine running, so I don't do this.
A charged battery is ~12.6V and with the engine running, you should have ~2V more.

Re: Electrical issue
 

When my truck is running there are 14v comming from alternator and 14 at battery. When it is not running battery is in the 13v range. When truck is running Guage on dash says 11.6v. When I turn everything I can on it drops to 9v batter and alternator still shows 14. There is a connector near the battery where several grounds are coming together before connecting to inside of fender behind battery. I will post a picture. This connector just got hot and started to melt

Re: Electrical issue
 

That connector is for a house not a car. Probably a bad ground, the other end of the negative cable.

Re: Electrical issue
 

truck is fixed. fixed my melted ground and got a 1 wire alternator. thanks