I have a 2002 F350 dually with a 7.3 diesel. I had a windshield leak that dripped water all over the electronics left of the steering column. The alarm went off during a rain storm and I shut it off with the key fob as normal. When I re-set the alarm, it went off again a couple hours later. I turned it off and left it off. The next morning I went out to start the truck and it would not turn over. All other indications in the start sequence were normal except that the starter did not engage when the key was turned to the start position. I thought the alarm ignition lockout had been activated. All attempts to get around this failed. I went to the alarm manufacturer (Silencer) and they told me to disconnect the power plug from the alarm module at which time the truck would be returned to normal operation. It still did not start. I pulled the fuse panel off and found water in the cover. I pulled all the lower bank fuses, cleaned and dried them and put them back. I found one fuse blown # 113 which is listed as the starter motor and thought I had found the problem. I replaced the 30A fuse and tried to start but the fuse blew immediately. I then looked to the starter relay # 307 in the fuse box, pulled it and tested it for function and it checked out fine. Now I am at a loss. The wiring diagram I have in the Owners Guide, and in my after market maintenance manual does not detail this circuit that uses fuse #113 so I have no idea where else to look for the short. Can anyone provide suggestions, or a link to a wiring diagram so I can trace out this circuit and find the short? Thanks!

 

A common failure related to a 30A fuse is the fuel bowl heater. You can unplug that and see if it helps.

A leaking windshield usually takes the GEM out, but I believe your 2002 has a different module that takes the place of the GEM (VSM) I believe it's behind the fuse block... maybe somebody else can chime in. I do know that some have taken the GEM out and cleaned up the board after a soaking and that fixed the problem. You may be able to do the same.

You might try blowing air in the fuse block to clear whatever moisture may still be left in there.

I have no reference to a fuse 113 in my documents. Could the fuse be F1.13? I'm still looking at what suspects could possibly be by your left foot.

F2.50 is 30A and that powers your VSM. I wonder about that one.

 

Thanks Tugly,
I did dry out the fuse block and pulled all the lower fuses that were exposed to water in the lower row and cleaned them. The fuse designations I am using are the ones called out in the factory User's Guide and on the fuse box cover. The book says fuse #113 (30A) is "Ignition". Pretty vague. I do not have a wiring diagram and have not had any luck finding one on line un less I wanted to spend $75 for a complete set of schematics. (and I do not). Seems like there should be someone out there that knows what this circuit entails so I can trace it out and find the problem.

 

Quaint. There is no "Ignition" on a diesel. Have you downloaded the free owner manuals (including the diesel addendum) from owner.ford.com?

 

the VSM is located on the firewall behind the radio..

 

Spray the VSM and the fuse block with WD40. The "WD" in WD40 stands for Water Displacement. It will get rid of any residual moisture that may still be present. It will stink if you don't like he smell, but it will get all the moisture out.

 

Same thing happened to my rig but my issues were the interior courtesy lights and windows didn't work. Long story short my fuse block was shorted and had to be replaced. Unfortunately, the fuse box can't be opened or at least I couldn't open it without destroying it. I found one on Ebay for about $75.