# Help 02 7.3 f550 starting problem



## 518Landscapes (Dec 1, 2010)

i HAVE A O2 F550 7.3 

This morning went to start to go on a salt run, and nothing wont start. only thing doing anything was the instrument cluster was flickering and making a buzzing grumbling noise, in the run position or start position. I drove this truck two days ago and parked it in the shop working fine:realmad:

check and charge battery's OK
Starter, new 2 months ago check OK
key on or off no head lights, turn signal, hi beams etc.
not getting power in cab it seems.

Some times When you pull the key out of the ignition the truck electrical will stays on if not totally in the off position. so I was thinking possible ignition switch failure. Or bad ground

If any one has any insight on a possible diagnosis it would be greatly appreciated


----------



## Greenery (Jun 23, 2007)

I know you said you checked your battery, but that's what sounds like the problem is to me.


----------



## 518Landscapes (Dec 1, 2010)

ya I know, I put new battery's in it from Napa today as well and the same result. Still no luck


----------



## fordtruck661 (Feb 26, 2011)

your cables running from your batteries may be bad. Check to see if they are all corroded


----------



## Plowtoy (Dec 15, 2001)

Clean both batteries connections. Even if there's not much visible corrosion, I would clean them and dielectric grease them.


----------



## dieselss (Jan 3, 2008)

Drivers inner fender behind the airbox. There's a junction box that powers the cab pwr. An 8 gauge wire, and 2-4 wires branching off it..start there


----------



## deicepro (Mar 24, 2009)

Mine does that, wiggle the battery cables....


----------



## fordsuvparts (Jan 7, 2008)

There is a wire that connects to the alternator that has a fusible link that goes bad and can cause some of those problems. I would check all the connections on the starter and the starter relay on the passenger side inner fender right behind the battery. The cables can be corroded but look fine, check each ground and power connection, especially the battery cables you need to clean them very very well.


----------



## dieselss (Jan 3, 2008)

Hey Ford,,I think you might be wrong. Not that I have seen a 550 in a long time,,but if its the same as my 350,,,there isn't a starter solenoid on the pass. Side fender. The truck gets its inside pwr from that pwr box on the drivers inner fender,,not the pass side.


----------



## Snowdog22 (Jan 11, 2007)

possibly the ECM which is located behind drivers front tire fender....mine did the same thing a few years ago. $300 at dealer and running again. Look for about 100 wires running into fire wall below and right of master cylinder


----------



## Milwaukee (Dec 28, 2007)

Before throw any $$ down drain

Find buddy with scanner that will work with powerstroke.


----------



## A.M.Canfora (Nov 2, 2011)

clean all the cables it is probably a ground issue. The dim blinking lights and the buzzers sounding like there sick is a good indication. When you go to crank the truck is there any clicking noises?


----------



## 518Landscapes (Dec 1, 2010)

OK, up date on the f550 after tracing the + wires from batteries. I found a bulk head connecting three wires behind the air box on the driver side inner fender, it is covered with a plastic cap upon removing the cap it was full of green corrosion this is a common problem on these trucks I guess. I Eliminated the box changed the terminals, bolted them together shrink tube and taped it good as new lights are brighter then ever had it running the same night.Thumbs Up Bad design in my opinion.

Thank you everyone for the help

dieselss you were right on the money with your diagnosis.



dieselss;1434668 said:


> Drivers inner fender behind the air-box. There's a junction box that powers the cab pwr. An 8 gauge wire, and 2-4 wires branching off it..start there


----------



## dfd9 (Aug 18, 2010)

fordtruck661;1434515 said:


> your cables running from your batteries may be bad. Check to see if they are all corroded





dieselss;1434668 said:


> Drivers inner fender behind the airbox. There's a junction box that powers the cab pwr. An 8 gauge wire, and 2-4 wires branching off it..start there





518Landscapes;1436664 said:


> OK, up date on the f550 after tracing the + wires from batteries. I found a bulk head connecting three wires behind the air box on the driver side inner fender, it is covered with a plastic cap upon removing the cap it was full of green corrosion this is a common problem on these trucks I guess. I Eliminated the box changed the terminals, bolted them together shrink tube and taped it good as new lights are brighter then ever had it running the same night.Thumbs Up Bad design in my opinion.
> 
> Thank you everyone for the help
> 
> dieselss you were right on the money with your diagnosis.


Too late, same thing I was going to suggest. Had this happen on 2 of mine last year. What a stupid location as well as totally unneeded connection for this thing.

Another Ford engineer with cranial rectal inversion.


----------



## dieselss (Jan 3, 2008)

No prob 518. Nice to share what I have found over the years. Glad ya got it fixed and working again...now,,,,just need snow


----------

