The battery is strong, but might as well be gone altogether. No lights, no open door signal, no gauges, NOTHING!! Is there some "kills everything" fuse on this thing? Thanks for any ideas.

 

Usually, that's a bad cable or connection, assuming the battery is actually good and is fully charged.

 

Cables are good and all connections are clean and tight.

 

Then do your voltage drop testing under load to find the fault.

Did you check the fuse links in the main feed from the battery to the connection on the starer relay?

 

I'm pretty green at this. Guess I'll search voltage drop test. Would the fuse links stop all power to everything??

 

Yes, if open.

 

Hang on a sec here...

Starter power is a straight line from battery positive, same with Starter relay terminal 30. Starter relay terminal 85 is from the ignition switch and goes through the main fuse box.

Pull the wire off starter relay 85 (the small wire) and see if it reads 12v when you put the key to start. If it reads fine, your cables are suspect. Not a big surprize if they're the original Ford factory crimped ones. Do yourself a favor and solder new ones yourself

 

He said he had no power, including lights, etc - "NOTHING" was the exact description used.

Except for the main power feed to the starter motor, ALL power for EVERYTHING else has to go through the fuse links. Checking the small terminal in START is a moot point since NOTHING has power, assuming that's actually the case.

BTW, I learned a long time ago that just because something "looked" good does not mean it actually is good.

 

I agree, but the point of checking the starter relay trigger wire by itself is to see if it is working WITHOUT the 100+ amp load of the starter dragging things down. A marginal battery will read 12v, but drop to 8v or less on cranking, making every other circuit fall off in the process. Found that out in the first startup of my 20B RX7. ECU kept shutting down because the voltage was being pulled down too low as a result of a crap Auto zone battery giving out. Swap in a new DeKa Intimidator AGM battery and she fired up easily and effortlessly.

Situations like this are why I keep a multimeter in my truck. My rule of thumb is that if it reads more than 0.6 ohms, it is bad. This is how I diagnosed corrosion inside the trailer battery charge wiring's insulation., it read a scary 2000+ ohms. When i cut it, all that was there was the blue powder called copper oxide.

When checking the starter relay trigger wire, observe if any of the same circuits fall off like before. If they do, follow Project SHO's advice. If not, examine the starter and cables. I suspect a bad cable.

 

He reported that there's absolutely no power anywhere....