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Took me 4 hours to diag a bad ground on a 2015 F-150 that had me stumped for 2 days
I had this F-150 come in with intermittent crank no start. Spent all day Tuesday chasing sensors, swapped a crank sensor, even checked the fuel pump relay. Finally I just sat there for 20 minutes watching the voltage drop on the PCM ground with a test light while wiggling the harness. Found the ground bolt under the battery tray was loose, like finger tight. After rust and corrosion it barely made contact. Anyone else had a simple ground wire waste a whole afternoon?
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kim.nina3d ago
Dude idk I feel like you gotta check grounds first before you do anything else lol. I mean a loose ground bolt under the battery tray, that's like one of the top 3 things to look for on any Ford from that era. You spent 2 days on a crank sensor and fuel pump relay when a 5 minute wiggle test would've saved you all that time. I've seen so many techs go nuts chasing sensors when 9 times out of 10 it's a dirty or loose ground somewhere. You probably could've skipped the whole sensor swap and just started under the battery tray from the start. It's frustrating but sometimes you gotta learn the hard way that grounds come first on these trucks.
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the_max3d ago
Nah, I gotta push back a little here. Yeah grounds are important and definitely a common issue, but a loose bolt under the battery tray isn't always the magic fix. I've seen plenty of Fords from that era where the Crank sensor was legitimately bad and a new one fixed it right away. The wiggle test is a good first step for sure, but sometimes you're dealing with an intermittent failure in the sensor itself that won't show up until it's hot or under load. So chasing that for 2 days isn't necessarily wasted time if the grounds check out fine early on.
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phoenix5733d ago
Funny you mention that @kim.nina cause my buddy had a 2001 F-150 that would die randomly for weeks until he finally swapped the crank sensor and it never stalled again after that. Did the wiggle test first too and got nothing but a sore hand, so sometimes you just gotta trust the parts cannon over the bible of grounds right?
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