Truck won't start, no dash lights, no theft light.
Hooked up to charger and it will crank, have dash lights, have theft light.
Using the engine start option on the charger we have weak dash lights, intermittent door open/key in ignition dingdingding.
Truck will not start.

We thought it was the starter, but with the immediate change in the juice flow with the charger on, why is it more active with the charger on and completely dead without it?

Same thing with the ignition. If it was the ignition module, why is there a marked change in it trying to start once the charger is hooked up?

Any ideas?

 

Welcome to the forum

A car Battery uses a chemical reaction to store and release voltage, so they do wear out, 5 to 6 years

And 12volt batteries have 6 separate cells with 2.1volts each, so 12.6volts is a good battery, NOT 12.0volts, thats a bad battery

So you need a volt meter first, test battery to see its volts, if 12.2v or lower its a failed battery

If one of the cells is shorted, common thing to happen after battery is 4 or 5 year old, then battery will be in the 10 or 11 volt range, and you can watch it go down just using volt meter, so toast

Booster/starter on recharger unit can't generate enough amps if the battery is bad, it can only be used with a good battery but with a low charge, i.e. you left the lights on or similar

Starter motor needs 60+ amps to crank engine, unless you spend about $200 on a booster it won't have that regardless of what the label says, and a bad battery will SUCK 1/2 the amps away when you try to boost it, so................check that battery

And always clean BOTH battery terminals at the first sign of slow or no crank

 

Original assembly line battery was replaced with new in July 2018 by Ford dealer.

 

Thats good but doesn't help, what its voltage now?

Should be 12.7v at least if less than a year old

Can't tell you how many "new" batteries I have had to take back after a few months to warranty exchange, lol, but I am old and worked on lots of cars

 

We'll be back in a couple weeks to keep trying. Will test for voltage on the new battery then and report back. At least we might be close to nailing it down. Need this truck for summer farm work.