Crossed the battery cables and shorted electrical system?

JEFF VON HOENE

MEMBER
1998 FORD EXPEDITION
5.4L
V8
4WD
AUTOMATIC
170,000 MILES

Tested the primary battery fuses on the firewall and replaced a 175amp bar fuse. Tested the fuses in the engine fuse box -all good; then the interior fuse box, only 8 in the top left corner get power (1-4; 12-15). I can’t find the starter relay switch and have not tested the starter solenoid.

Sunday, December 4th, 2022 AT 9:06 AM

1 Reply

AL514

MECHANIC
5,265 POSTS

Hello, unfortunately when this happens one or more modules usually get damaged from the current flow on the ground circuit. I will cause some fuses to blow, but by the time the current flow gets to the fuse it has already taken a path through a module to get to the fuse. And a 175amp fuse is a huge fuse with a lot of current flow to damage that one. The first thing to concentrate on is the engine computer. It has 6 ground wires that I see so far that go directly to battery negative. As well as the security system module. Does anything happen when you turn the key to just the on position, no cranking? Do you see a Check engine light?
How long was the battery hooked up in reverse polarity as well?

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Sunday, December 4th, 2022 AT 12:39 PM