Hello, Long-time lurker around here and I finally had an issues that many web searches could not solve. (Read: this site has been super helpful for many, many things!)

I have a 2001 Ford Excursion 7.3 w/ 248K, a few mild mods but nothing crazy.

I had a no start issue that continually perplexes me, hopefully someone one here has seen something like it.

Truck never has any real issues starting so this was out of nowhere, After driving in the rain and sitting for a few hours, I went to start it up. Everything normal, WTS comes on and goes away as normal. I go to crank it over and the truck instantly looses all power. It never tried to crank, no "click" from the relay, nothing.. No dome lights, no head lights, nothing. It was as if the batteries were physically disconnected at that moment. Power doesn't come back until maybe 10 mins. I try again, same thing. All is normal until I crank. Then nothing, lights out. It got to the point where I remember just putting the key in and it would just all die. The batteries had a fine charge (jumping didn't help), after 10 mins or so the headlights were bright and domes & all electronic would return.

Called a tow truck the next day (had to get a ride home 1.5 hr drive!) Back at the truck the next day-same thing. I brought tools to fix it, but couldn't figure anything out! Before the tow truck arrived, I tired again and it fired right up. Haven't had a problem since, but I am worried! And in the mean time I'm scarred to drive far again! Help!

Other notes; since this issue, the truck has sat more (still scared to drive too far!) and will occasionally crank slowly after sitting, developing a P1670 code, which I feel is similar to how 6.0Ls blow out the FICM upon weak batteries. P1670 relates to the IDM IIRC, and other than the code, the truck is fine. Replaced w/ two new Interstate Megatrons as I figured the previous ones might have been somehow defective after 2 yrs. Who knows. Could a starter cause an intermittent excessive draw? What circuit is on a timed-reset fuse? To cut all power it has to be close to the battery on the wiring diagram, but I am lost.

Any insight is awesome!

Oh, and lastly, the Ford Stealership had no clue, and charge me $70 for nothing!

 

check fuse box for corrosion from a leaking windscreen. Also pull the IDM relay and clean the terminals. I had the second problem which cause a no start.

 

I will look up IDM relay, and try that. This happened a while ago, but I am driving the truck around town increasingly and it seems to start great.. Any way your idea coincides with intermittency? Cleared the code so I assume it would have returned it the p1670/ idm was a pressing issue.

 

Not sure if your truck has the same junction but see if this thread helps
https://www.ford-trucks.com/forums/1...l-failure.html

 

X2 on what he said! ^^^^^

 

Thanks a bunch for the replies, I have just read over that thread twice, it sure seems like a similar problem! I have a 2001, which means I don't have that specific junction, but Maybe its worth poking around the engine bad and following the main battery leads to see where I end up. Too bad EVERYTHING is buried deep within the harnesses!

The only other issue btwn that and mine is that mine was so ignition tied. I cant figure out what type of starting circuit has a "timer" or what is able to interrupt all power

Grounds at the starter were healthy.. Originally an AZ truck and Im from MI, so its cleaner than average around here.

 

After originally reading that thread, everytime I remove battery box I look at it.

 

I did not see where you removed and cleaned the battery terminals. Terminal corrosion can cause the symptoms you describe.

Since jumping did not work, you could have a bad engine ground connection. It is located on the back of the passenger side head.

I don't think it is the batteries, because you said jumping made no difference.