Friday, December 4, 2020

Alternator Not Charging Due to a Broken Terminal

Not long ago I had to repair a broken wire from a fusible link. And this time, the alternator-and-battery plug from the alternator called it quits.

Above: Decades-old wiring and connectors eventually fail.

However, I was very fortunate that this malfunction took place in the comfort and safety of my garage.

Since my car needed gas, I decided a quick trip to the station was in order. But, as I cranked the Vette, the sluggishness of the starter immediately indicated there was a problem. The car started, but the ammeter needle was reading into the negative, so my first thought that was my fairly new alternator had failed.

I turned the car off and opened the hood, and as I was looking around to determine what bolts would have to be loosened to remove the alternator, I tried to unplug the connector shown above, but as I removed it, one of the wires popped off, and from its looks, it was easy to see that the connector and not the alternator itself had failed.

Out of the two wires, the brown one and its connector were fine, so I disconnected the battery and removed the old and brittle plug to do a temporary repair to get the car running and charging properly.

With the original alternator plug housing on the workbench, it was easy to see that the best course of action would be to simply replace it.

Above: From the looks of it, it appears old connectors were made out of copper.

These connectors are quite common, and most auto parts stores will have them in stock. However, I wanted one that looked close to the original, and Amazon had one in stock for around $7.50 including 2-day Prime shipping.



The ones available from the local auto parts stores were either solid white or black. Not a big deal, but I wanted the translucent white plug.

While I waited for the new plug to arrive, I cut off the remnants of the original connector and stripped the 10AWG wire to accept a new female spade connector, which I crimped in place.

Above: Notice the nice and strong factory double crimp.


Above: I added a piece of heat-shrink tubing for good measure.

My repair does not allow me to use the old connector housing, which is okay for the time being since this is just a temporary fix.

And while it does not look OEM or even pretty, the repair worked as intended which allowed me to test-drive my Corvette to fully recharge the battery.

I could've stopped at this point and my Corvette's alternator would have charged the battery just fine, but repairs such as these, look like a band-aid and that's not okay with me.

The replacement alternator pigtail arrived a couple of days later and I immediately got it ready to be installed in the car.

For all intents and purposes, it was identical to the original except for a couple of small details. First, the factory connector housing had A and B stamped on the plug, A for Alternator, and B for Battery. The replacement part read Made In Taiwan instead.


The second difference was the Battery wire was white instead of brown, but that was easily corrected since the one in my car was in great condition and easily swapped. The red wire (I had to use that one since the terminal on mine was broken), appeared to be a 12AWG instead of the 10AWG wire in the car. Again, a small and probably inconsequential detail.

Above: 1976 Corvette wiring diagram showing the alternator wires.

Above: Keep Your GM Car All GM.


With the replacement wire out of the housing, I determined where I would need to splice the wires and I also removed a small piece of the wiring harness tape from the area.


With both wires cut to size and stripped, I proceeded to "fan" the wire strands to weave them inline for a nice and clean soldered joint.


I also cut a 10-gage terminal to use the ring to help hold the two wires together. I only crimped the terminal ring enough to provide a good hold but not too much as to deform or flatten it.


I used a welding blanket to protect components nearby and soldered the two wires. I used paste flux to ensure good solder flow and a solid connection.



I also used two pieces of heat-shrink tubing to weatherproof the splice.



And as the two pictures above show, I also wrapped a portion of the wires with cloth harness tape for a cleaner look.

Like I mentioned earlier, I could've just left the first repair alone and it would have sufficed, but sometimes you just have to go the extra mile to make a repair look like it never happened, and for under $10 and less than an hour, I chose to do it right.

You will need a soldering gun, solder wire, and soldering flux past (always use flux), to get the job done properly. You could use a Solder Seal waterproof connector, but as much as I like them, I don't really recommend using one in this case.

Forty-year-old wiring can fail—and probably will—at some point, so having the tools and know-how to fix issues as they come up is a good idea. In most cases, these are projects most do-it-yourselfers can handle quickly and without trouble.

I hope you find this article helpful.


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