2006 f250 has electrical drain when ignition is turned on. You can see the lights flicker as the injectors cycle. Had alternator tested an it tested ok. Starter? Both batteries are good.

thanks for any help.

 

Time to start doing voltage drop testing on the power feeds. While your doing that you
also want to check all the connectors for crossion and any other damage.

The reason behind the voltage drop test is it will tell you how that section of cable is doing under stress.
The meter set to ohms may show a good reading even with a bad wire/cable. The voltage drop test checks
how well current will flow through the section your testing. The linked video will show you how to do the
test along with what the readings mean.

Here is a good How to video from Youtube. You can do this test on the ground side also.
If you don't have one now it a good time to pick up a DMM (Digital Multi Meter)

Please post back what you find. I am thinking that if the lights are doing funny things during the pre-start
when the injectors are chattering the issue may be between the battery and the engine bay fues block.
The name for that fuse box is BJB (Battery Junction Box).

 

Will do it’s my sons truck going over this morning to look at

 

So did some testing everything checked out then I remembered the remote crank on the truck cranked ( attempted to) and it drained all power from my battery. So assumption is starter. Replaced and does the same thing. Going to charge batteries and recheck. Left battery has nothing to do with starting? Had no bearing on tests when disconnected

 

The left battery, hoping you mean drivers side, is half the starting power. If it shows no voltage drop during stater engagement, then the cable between the two batteries positive terminals is broken, or one of the negative cables involved with the drivers battery is an issue. The primary negative cable goes from the battery to the drivers frame and the secondary cable goes from the passenger frame to the engine block.

 

Here is a diagram of power distribution and grounds along with a few other things.

 

Thank you all for the info will pos when I test again

 

Both batteries have the voltage drop when connected. The starter draws the voltage down when engaged after contacting the flywheel. M

 

Then what were you doing to make this statement? Engaging the starter with the passenger battery only?

 

yes I had just to see if there was any difference in the draw. Don’t really know what is was thinking I know it needs both batteries to start. Me having a brain fart 💨 🤪.

 

When you first turn the ignition on the glow plug draw can be up around 200a, and the injectors cycling through the check can also be up there initially. That drops to a lower value steadily as the amp demand by the glow plugs drops to about 85 and steady by the time the wait to start lamp goes off. Then you are going to add the starter demand. Initially to get the starter to move it will be up to around 1,500 amps for a millisecond, then be continuous at about 400-450 amps.

Lights dimming during those loads can show some voltage change, but from a subjective nature, that's a hard call. You need to observe the voltage during that time to better understand what's happening. You mentioned the batteries are good but have you had them tested for free at an auto parts store like Advance or Autozone? If so what were the values? Some will give you a printout, or you can just write down the valves at the time.

The condition all of the connections can have a dramatic effect on voltage drop as well. And it's not just at the battery terminals but where the battery cables are attached, negative and positive. But before you go down that path, battery capacity and voltage conditions need to be known.

Also, if you can take a picture of the tops of the batteries and post them here some the members can see if there is anything we've seen in the past would help the story.

 

Will do will be looking at it later this evening will post a pic or two . Again thanks

 

So charging the batteries got it started but the alternator has 13v in not running but on outs out 11 v. Have 13v one side of excite wires and 0 other side with key on

 

 

If at 11 volts during running, the alternator is not working or the main cable has blown its fusible links.

Excite wires, I assume you are talking about the multipin connector on the alternator. Yeah, key on should have voltage on both sides.

This connecting cable between the two batteries had broken and a lug installed on it. Hopefully well or that can be a big issue.




You do have the negative terminal on this side connected to the post when starting, right?




Here's a quick layout of the main circuit.





Your definition of the excite wires would be here? My connector and colors are an aftermarket replacement part.









You could put the multimeter on volts, with negative lead on the passenger battery and positive lead on the driver's battery, engage the starter and see what the voltage drop is. Or ohm across the positive posts (ONLY)


This video of mine might be of some help.