2018 super duty strange electrical issue.
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Mountain Pass
Joined: Jul 2018
Posts: 243
Likes: 18
From: PA
2018 super duty strange electrical issue.
I have a 6.2l 2018 super-duty with around 50k miles. This weekend I was towing a camper, suddenly my air bag light would come on and make a click sound when braking. After dropping the trailer it continued but now also says “trailer battery not charging see manual,” while there is no trailer in addition to the air bag light coming on and off. Also, my directional will randomly speed up as they do when a bulb is out at the same time at a light. Googled all over and can’t find anyone with the similar problem. Anyone have any thoughts?
More Turbo
Joined: Feb 2017
Posts: 566
Likes: 105
I own a 2017 6.2 and from reading the forums in the past, when you get electrical glitches, the first thing you should check is the battery(ies). If they are not good, it can cause this type of thing. And from reading previously, really check them at a shop that knows batteries.
More Turbo
Joined: Feb 2017
Posts: 566
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Fleet Mechanic
Joined: Apr 2015
Posts: 1,641
Likes: 507
From: Phelan CA
I have a 6.2l 2018 super-duty with around 50k miles. This weekend I was towing a camper, suddenly my air bag light would come on and make a click sound when braking. After dropping the trailer it continued but now also says “trailer battery not charging see manual,” while there is no trailer in addition to the air bag light coming on and off. Also, my directional will randomly speed up as they do when a bulb is out at the same time at a light. Googled all over and can’t find anyone with the similar problem. Anyone have any thoughts?
Take a meter lead from the engine block to the frame with ignition off and make sure you get zero ohms as well as frame to batt negative and cab to frame etc. (DISCONNECT NEG LEAD OF BATT SO YOU DON'T BLOW YOUR METER FUSE!!!)
Repeat same test this time in volt scale and with ignition on, make sure there is no potential difference on each component.
It's also easy to check alternator charging voltage, make sure it's around 14.5 volts.
Lead Driver
Joined: Oct 2014
Posts: 5,943
Likes: 1,357
From: NY/Canada border
Mine was with a 2017 that was less than a year old. Dealer replaced under warranty.
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Mountain Pass
Joined: Jul 2018
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From: PA
Battery, alternator and ground all tested good. Nothing that I can see for moisture around the plug near the spare. Today I have more things starting to add to the mix. One being “check park system light” on dash going on and off with others and the hvac system staying on when in park, ignition off and key removed. Sounds like a trip to ford is in store.
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Lead Driver
Joined: Oct 2014
Posts: 5,943
Likes: 1,357
From: NY/Canada border
Battery, alternator and ground all tested good. Nothing that I can see for moisture around the plug near the spare. Today I have more things starting to add to the mix. One being “check park system light” on dash going on and off with others and the hvac system staying on when in park, ignition off and key removed. Sounds like a trip to ford is in store.
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Mountain Pass
Joined: Jul 2018
Posts: 243
Likes: 18
From: PA
Sure did. Went out and checked again. Dropping it off at Ford tonight. Luckily I did by an extended warranty from flood ford which has a year left.
Lead Driver
Joined: Oct 2014
Posts: 5,943
Likes: 1,357
From: NY/Canada border
You could tell then. They get black and nasty looking if there's water intrusion and corrosion. I hate trying to chase stuff like this.
Logistics Pro
Joined: Sep 2002
Posts: 4,411
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From: Central KY
My cousin just went through this on his 2020. The auto parts store "tested" his batteries and said they were good. The random issues continued. He finally took it to a dealership and they did a proper load test on the batteries and found that one of them was failing the load test. Two new batteries and all his issues went away.
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Mountain Pass
Joined: Jul 2018
Posts: 243
Likes: 18
From: PA
Time to trade in LOL
Fleet Mechanic
Joined: Apr 2015
Posts: 1,641
Likes: 507
From: Phelan CA
You have an issue with an intermittent short or poor ground. I don't think it's your ignition switch. The ignition switch can be easily checked with a scanner and live data, so it's easy for any mechanic worth their salt to do.
The HVAC module not sleeping is a key issue. Is it repeatable? Do you have remote start?
I'd do a visual inspection of the under hood wire looms.
Don't touch anything! This problem screams intermittent caused by insulation failure. Perhaps you can see the harness rubbing against the block, frame or a bolt.
If you go in there and start messing with wires, it may go away for a while.
You could try to get it to repeat and while the HVAC is running with key out, gently and systematically move specific parts of the harness, until the system shuts off.
Hopefully the dealer has a GOOD diagnostic technician. I would refuse any parts replacement unless it has been proven to be the cause of failure.
The HVAC module not sleeping is a key issue. Is it repeatable? Do you have remote start?
I'd do a visual inspection of the under hood wire looms.
Don't touch anything! This problem screams intermittent caused by insulation failure. Perhaps you can see the harness rubbing against the block, frame or a bolt.
If you go in there and start messing with wires, it may go away for a while.
You could try to get it to repeat and while the HVAC is running with key out, gently and systematically move specific parts of the harness, until the system shuts off.
Hopefully the dealer has a GOOD diagnostic technician. I would refuse any parts replacement unless it has been proven to be the cause of failure.