This 2002 GMC Sierra came in with the complaint that the battery had gone dead and that the voltmeter was reading low voltage at times. I opened the hood and the problem was quite evident to me but I decided to do some testing anyways. The following picture shows 14.32 volts at the alternator output stud. Engine running of course.
This is the obvious problem. A poor connection at the positive battery cable jump point.
Someone had wired in an electric cooling fan system and taken the mechanical fan assembly off.
While testing, I decided to check the temperature of the connection. The connection, as you can see was at 289 degrees F. The vehicle had only been running about 2 to 4 minutes at this time.
The voltage was only 9.98 volts.
The stud had melted loose of the insulating block assembly.
And there is the actual reason for all of this mess. Bare wire twisted around the stud with no terminal. On top of that the curve of the wire is even wrong for household wiring. See how the wire is hooked CCW. At bare minimum it should have been on there in a CW direction so that the loop would have tightened as the nut wast tightened. Didn’t we all learn that in high school electricity / science classes.
The plastic in the insulating block was badly melted however the cable eye terminal was just a little dirty.
A quick cleaning and it was good as new.
I checked locally, the fusible link from the alternator and the insulating block both had to be ordered. So I continued cleaning up the mess.
There sure has been a lot of heat on that stud. At least 289 degrees F, right.
I surely do love having a glass bead cabinet. I cleaned and tightened all of the connectors and epoxied the insulating block. The system is now operating properly and I will install the new parts when they arrive.
To see how to properly install a fused circuit on this and similar trucks please click here.