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Ford
F-250 Dome Lamp Dilemma
You don't know Jack.
Jack Andrews that is. He owns the finest car wash in town. About six months
ago, Jack brought his customer's 1994 Ford® F-250® pick-up into
my shop. The truck had been in for a wash and detail and ended up with a
major electrical problem.
As the
story goes, a local pumpkin farmer, Earl McClure, had won first place
in the "43rd Annual Giant Pumpkin Contest." The judging committee
asked Earl if he could tow the monstrous gourd on a trailer behind his
truck in the Harvest Day Parade.
Since
it had been at least three years since its last wash, Earl thought a parade
was a good excuse to get his truck cleaned-up. He dropped it off at Jack's
Car Wash for the "Turbo Tornado" complete wash and detail.and
there's where the problems started.
 After
the truck was washed and detailed, Jack decided to do Earl a favor and
deliver the truck back to Earl's ranch. But on the way there, he noticed
a long list of things had quit working. The dome, vanity, map and cargo
lights; engine and glove compartment lamps; power mirrors; remote keyless
entry system and the odometer all had stopped working at the same time.
Jack
brought the truck to my shop in hopes of finding a simple, logical and
inexpensive solution to his dilemma. Luckily, that's exactly what happened.
While reviewing the factory technical service bulletins on my ALLDATA®
automotive information system, I found one that outlined the problem perfectly.
The bulletin
stated that on 1994-95 Ford® Broncos®, F-Super Duty® and F-150®,
250® and 350® series trucks, two of the three screws required
to mount the map/dome lamp to the inner roof panel of the cab, are also
used to complete electrical circuits 53 and 54. Circuit 53 is after the
lamp switches and is "cold" (12 volts not present) and Circuit 54 is before
the lamp switches and is "hot" at all times (12 volts always present).
The screws
from the factory are approximately one inch long. When there is a sufficient
amount of downward force applied to the outer roof panel of the cab (example,
when the brushes and dryer pass over the roof of the truck during a car
wash), the roof panel contacts the screw, and causes a direct short-to-ground.
When this occurs, Fuse 8 will be overloaded and disable Circuit 54, which
powers every component listed above.
The fix
is easy. Replace existing dome mounting screws with new, shorter screws
or simply grind\cut a quarter inch off the old screws and reinstall them.
Replace fuse 8 and recheck all the effected components for normal operation.
I got
the truck in and out of the shop in less than an hour. Jack was extremely
relieved the problem wasn't terminal. He happily paid the bill, tipped
me and returned the truck to Earl. To this day, people are still talking
about Earl's giant pumpkin and Jack's still talking about how I must be
the smartest auto tech he's ever known.
©
2000 ALLDATA LLC
Written
by ALLDATA Technical Editor, Rich Diegle.
Rich is an Advanced Engine Performance Certified and ASE Master Technician with
an Associate of Arts degree in automotive technology and 22 years of dealership
and independent shop experience.
ALLDATAź
is a registered trademark of ALLDATA LLC
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