ONE shot, One kill? How about ONE symptom, One guess??

[bamaboy473]

2000 F350 7.3L with 136K miles and runs fine for the 700 mile trip home.

Two days of cleaning it up and the truck sounds like a dead starter solenoid....either a Click or not even that. Two or three times trying it and then the truck turns over quick and starts like a champ. WTH?

Batteries clean and charged up to 12.63V+. nothing different. I swapped batteries with the Excursion, same thing. Finally got the truck running on the third try. Another clue: when I opened the door to try the starter, not even the dashboard lights came on. finally I started it, Then while it was running I checked voltage...TaDa!

Right side shows 14.18V while truck is running...good deal.

Left side shows 12.41...down from 12.62 at rest.

How can I have that happening? I'm checking the Pos cable that ties the two batteries together for continuity tomorrow, but other than a bad cable, how can that be?

What can cause a truck with two good batteries and all battery cables clean to have way different alternator inputs...and show signs of a failing or failed starter or solonoid?

[scott52575]

battery or cables going to poop

[willie59]

Just a guess, likely the ground cable on left battery. The two batteries share a common positive cable, but have their own respective ground cable. Take away the ground, battery won't get charge, it's disconnected from the circuit. Could still be the positive cable that joins them as well, can't count that out. Continuity test may not yeild useful info because your problem sounds like a break in the circuit under load. For example, I have seen nice clean moulded battery terminals that on the outside look perfectly fine. After determining the cable is faulty, and replacing it, cut apart the lead moulded terminal to find corrosion on the inside causing bad connection between moulded terminal and cable. A cable like this can test good for continuity because continuity impedance is low. It's under high amp load, like starting, then the corrosion and resulting bad connection can't carry the amps and breaks the circuit. Hope ya find ur gremlin.

[bamaboy473]

Thanks, Willie59, Trace the Pos cable and also trace the Ned cable. Come to think of it, when I removed and cleaned the Neg Left cable today, I noticed a crack between the battery clamp and the cable sheathing. Added a lot of baking soda/water mixture, but now I need to look harder at that cable.
On a boat, it would be a sure sign of bogus...why not a PSD?

[willie59]

Originally Posted by bamaboy473

Thanks, Willie59, Trace the Pos cable and also trace the Ned cable. Come to think of it, when I removed and cleaned the Neg Left cable today, I noticed a crack between the battery clamp and the cable sheathing. Added a lot of baking soda/water mixture, but now I need to look harder at that cable.
On a boat, it would be a sure sign of bogus...why not a PSD?

Your welcome bro, I hope that turns out to be your problem, something simple. Simple is good. The fact you switched batteries with the Excursion kinda eleminates a battery problem. Just sounds like a bad ground cable on left battery. Good luck.

[bamaboy473]

I'm going to McGuyver another ground strap for the left battery and see whether charging voltage changes. If it goes up, then that pretty much confirms that I'll be getting a new ground cable. Since yesterday was the day to clean/replace all bulbs and clean battery cable contacts, the act of moving that cable around might have just caused a weak point to finally break.

On the off chance that it isn't the cable (or isn't just the cable), what would be the symptoms of a CPS going bad?

[bamaboy473]

Well, back to the drawing board, I think. I took a piece of ground wire (the heavy type you use on a home) and ran it from the Neg post to one of the coil springs, and touching the body as well. NO change; right is charging @14.12 and left still at 12.43V.

Next I ran the wire from Right Pos to Left Pos. Clamped them, protected the engine compartment in case something came loose, and started the truck. I really expected to see charging voltage the same on both batteries this time. NO change.

First, by-passing first the ground strap and then the Pos cross-battery lead changed nothing.

Second, changing out the batteries did nothing.

Third, static voltage on the batteries is 12.62, and while running we're seeing 14+V on the right side battery, so we assume that the alternator works fine, can't we?

If it isn't alternator, isn't batteries, then was my testing with the ground wire enough? It didn't make .02 bits of difference in voltages. Installing new cables is an option, but let's figure out what I've missed, because right now I'm not convinced that the battery cables are the problem.

Just not getting charging voltage to the left-side battery.

[bamaboy473]

I found the problem.

Went and disconnected all the battery cables (again) to lightly sand each one again, then wipe with naphtha and wipe the posts, too.

Danged if I didn't see a good chunk of black tape inside the Pos connector that would have insulated the connector from the post. Tape came from the sheathing on the cable and it couldn't be seen from the topside. Hard to see with it off, too, what with the Corrosion X I'd sprayed on them.

Anyway, all the cables are good, batteries good, everything charging and I'm feeling like a clown.

Thanks for all the help, guys

[willie59]

Cool beans, glad to hear you found it.