2002 F-250 7.3 wont crank when damp or raining

[snyda88]

After having the PCM replaced by ford my truck wont crank when damp or raining. My batteries and alternator are good as tested by the dealer and they put a new starter on because they broke the terminal off the old one. I have to unplug the wire under the hood and jump it to the positive post on my battery. the ford dealer told me it was a moisture related problem (no s*#t). IDK what else to check I cut the starter wire to install a remote start (since removed to be installed by a professional at a later date) which caused this whole fiasco requiring me to get a new PCM. I checked the starter wire on the ignition harness and even re-soldered it to ensure it had a good connection. Odd though once he truck is warm after "hot-wiring" it it starts/cranks with no issue. This will be the third straight week my truck has been at the dealer unless you guys have any ideas.

[kaya@bernhausen]

i would start by checking for power in the start position at the ignition switch

[NoRalPh]

First, define "crank"...

Does that mean, to you, it's turning over on the starter but doesn't "start"?

OR does not "cranking" mean it doesn't turn over on the starter at all (like it does to me)?

This has always confused me

[snyda88]

Originally Posted by NoRalPh

First, define "crank"...

Does that mean, to you, it's turning over on the starter but doesn't "start"?

OR does not "cranking" mean it doesn't turn over on the starter at all (like it does to me)?

This has always confused me

No crank for me is dead silence after the relay clicks. I.E.- no juice to the starter.

[NoRalPh]

Originally Posted by snyda88

No crank for me is dead silence after the relay clicks. I.E.- no juice to the starter.

Me too (but not everybody I've learned)

So, on an '02, the starter relay is in the fusebox and looks like all the others (303 maybe?) If you hear a "click" that means the Ign sw and NSSW are doing their job. I assume that click is the starters Bendix not the 30A "cube" relay right? What wire, under the hood, are you "unplugging"?

And this is about Water? That's a weird one... You don't have a GEM up there behind the fuses, it must be a "current" issue (like a partial connection) but one that water effects because it doesn't happen dry. The High Current side (battery cable connections) wouldn't be so "sensitive". I'd be thinking the Low Current side, the "coil" side of both the Bendix and the 30A relay. Maybe jump that one as a test next time? If not the easy one, crawl under the truck with a jumper and jump the Bendix (look for the sm - yellow maybe - wire that activates the starter. It can be bent close to the body and short)

You got a puzzler there!

[kaya@bernhausen]

Originally Posted by snyda88

No crank for me is dead silence after the relay clicks. I.E.- no juice to the starter.

if the relay is clicking, ignore my previous statement, as the ign. switch is operating.
if you have a wiring diagram for the starting circuit and a DVOM, the problem can be resolved fairly quickly
since jumping the solenoid wire under hood works, it will be something on the signal circuit, before the under hood connection. that also tells you that the starter, solenoid wire after the under hood connection, B+ cable to starter motor, and ground cable are all good. that narrows it down significantly. just need a diagram to see what's left in the circuit

[NoRalPh]

I'm confused....

An '02 has no starter solenoid under the hood.

[kaya@bernhausen]

not under hood. at the starter assy.
to me, it sounds like the water may be causing a short to ground. that SHOULD however blow a fuse. but that would depend on where in the circuit that short were. since the fuse is going to be close to the power source, that theory may not be as likely. but still possible. either that or a bad connection. need the diagram

[NoRalPh]

To me, that's the Bendix...

So, I wonder what the "I have to unplug the wire under the hood and jump it to the positive post on my battery" is all about?

[snyda88]

I think when ford was in there swapping the PCM they unbolted the fuse box and loosens the harness that goes to the starter. I heard a definite click and after I got it buttoned up the truck cranked- and it was raining so think I got rid of the gremlin!


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