Found out today that my 72 cs is running on the battery. I replaced the alternator in january because the lights were running dim. Then 3 months later the truck would not start and acted like a dead battery. So I put in a new battery and a new voltage regulator. Battery still goes dead. After charging the battery up drove it to the auto parts where I bought the alternator and had them check the alternator. It showed that it was not charging the battery. While we were talking about the alternator he mentioned that the fuseable link from the alternator to the battery may be bad. He said to put power to one end and check current at the other end to verify the intergrety of the fuse link. Other than that I was thinking of taking the alternator bench tested. Any thoughts and ideas on this?

 

Hey 72, nobody ever told me about a fuseable link in all my years of wrenching. My cobra had the same damn problem and instead of buying batteries for my volt meter, I bought an alternator, then I bought a battery, then I went with a single wire alternator. After blowing all that money i finally broke down and put new batteries in my volt meter. Next, i pulled my entire dash and started doing some actual diagnosis with my volt meter. I found a wire that had a major voltage drop from the ignition to the starter. I noticed the wire had some writing on it. Turns out it was a fuse able link. I felt like I had been bent over. Not sure why these stupid things are necessary or used instead of a fuse cartridge but they are. Trace that wire with your meter. You'll find it. Good luck.

 

A fuse link is basically a " slow blow " fuse . They can take greater amps for a short period . A larger fuse that would take the amps could cause problems . Like melted wiring , burnt out components , Fire , ect . Had a guy replace his fuse link on a Dodge with a maxi fuse . When his wiring harness went up in flames , he found out it was not a good idea . While replacing his harness I found his short . It would have been much cheeper to fix than his fix turned out !

 

Thanks for the story and the encouragement. I feel like I am on the right track. Been working a lot of hours and may not get to it today maybe tomorrow.

 

How can a guy find a replacement for the fuseable link? I checked LMC and it looks llike I would have to get a whole new wiring harness.

 

don' confuse fusable link with the resistor wire(pink)

 

Fuse link can be bought in ready lengths or rolls . It can be bought at most parts stores .

 

Well I spent 5 hours yesterday unrapping the wires from the alternator to the battery and voltage regulator. Put power to the fuseable link wire and checked both sides, showed fuse was closed and working. Traced the other wires with power and seemed to be fine. So I removed the ground wires and cleaned where they attached and the connection on the wire to make sure I had a good ground. Checked to make sure the wires were connected to the alternator correctly and they were. I did notice a warning on the voltage regulator that it must be grounded before hooked up to battery. I am wondering if I shouldn't buy another regulator incase I did not have it grounded. Other than that I don't know why I can't get the alternator to charge the battery.

 

Do you have a meter to measure how much the alternator would be putting out if it was? I know you can jump the regulator connecting two of the terminals off said regulator. I dont remember which two, but that would be a Google thing. I suspect the alternator to be the problem. I have heard of aftermarket alternators that were built or rebuilt with solder that isn't high temp enough. More than once I've sold guys a Genuine Ford Reman alternator because they got tired of replacing the aftermarket one so often. I call those aftermarket ones "Spray-N-Pray".

 

A quick check is to put a metal object onto the rear bearing of the alternator to see if there is a magnetic attraction. If there is, it is producing voltage, but you need to check with a voltmeter like Jeff said. You can attach it right at the battery terminals. It should be in the 13.5-14V range, IIRC. If your battery was drained, you might have to get a new one. Charge it with a regular charger to be sure.