ARRRRRRGGGGGGHHHHHHH!

Most irritating. I have been through my wiring and still can't find why my battery is draining over night. Alt is charging. Battery is new.

 

Just because the ALT is charging does not mean it is not the cause, bad diodes can cause it.


Ok a few test to see where to look for a cause.
Using a test light put it between batt and a batt lead. If it lights up bright you have a large drain. If really dim a little drain say like from a radio but this would not kill the batt.


Now if bright remove 1 fuse at a time till the test light goes out, that is the system to look at fro the drain.


Now if that does not find the drain remove all wires going to the ALT and do the test light test again.


I also take it you have looked at the truck at night to see if any lights may be on really dim and not be seen during the day.
Dave ----

 

Each morning when I tried to start it I have been where I did not have access to any tools. Today I was prepared. When it barely turned the engine and then failed, giving only a click, I tested the battery. I was surprised to find it fully charged. The j/y relay from the 90's was bad. I replaced it with the oem relay and boom! full power and started right up.

I have a lot of family visiting, and when they leave I'll be able to install a 175 amp mega fuse in the + line to starter, but until then it is how Ford ran it, live all the time and unfused, and that bothers me. It will change.

 

Today I finally had time to dive into the search for the problem. I checked all the wires not oem, and some that were, for a short open circuit. I found only one live when the key was off. The wire had been cut at some time, and was lying there in the engine compartment. I sealed it up and secured it.

I also found that I had zero ground on the block. Wow. It does spin the engine faster, but I'll see what happens in the morning. The first start is when it has trouble.

 

So is it fixed or the truck been parked all this time?
If still has a drain try the test light across the batt. cable and start pulling fuses.
Dave ----

 

The truck is fixed. Thanks for all the help. Electrical work is my weakest area of automotive work. I had a bad starter relay. I also went through and cleaned all my connections and installed a new ground to the block.