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Discussion Starter · #1 ·
Guys,
I have a 2019 F250 that's been in shop for over a week now with a 5V reference drop and tech's can't find any short-to-grounds in wiring.
Truck is stuck in limp mode. Only has 9500 miles, deleted running GDP.
Any help/point in the right direction would be greatly appreciated, as shop seems to be at an impasse and I need truck back. They're talking new PCM possibly but thought I'd check here to see if anybody has dealt with any similar issues.
Dash light blinking with
1. Reduced Engine Power
2. Service Advance Trac
3. Hill Descent Control Fault
4. Hill Start Assist Not Available

Just happened randomly upon start-up in the morning, no issues at all prior to that.
Any ideas?
Thanks.
 

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If you have a voltage drop on the 5 volt line, then either a short in the harness or a bad sensor that uses that line

I do not have a diagram, but your mechanic should -- need to trace the line to all the sensors that use it and disconnect them

Does the voltage come back? if Yes, then reconnect the sensors one at a time and continue to measure
 

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Discussion Starter · #3 ·
If you have a voltage drop on the 5 volt line, then either a short in the harness or a bad sensor that uses that line

I do not have a diagram, but your mechanic should -- need to trace the line to all the sensors that use it and disconnect them

Does the voltage come back? if Yes, then reconnect the sensors one at a time and continue to measure
Thanks Hydro. Where would one go about getting a diagram for the wiring/sensor locations? I'm considering taking the truck back and doing this myself.
 

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You can either get the service manual from helminc.com or if you or you know someone who can get on the air force portal they have access to all the chilton manuals and they have all the wiring diagrams. I don't have my cac reader at home right now otherwise I would try to pull it up.

Sent from my moto z4 using Tapatalk
 

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Discussion Starter · #6 ·
Lemon or lemonade. Time to consider a buy back.
Yeah, was worried about that but not sure how I'd even approach it since I'm deleted. When this first happened I brought it into the local dealership because the service manager told me they were lenient with that sort of thing as long as the customizations weren't directly causing the issue, but when I brought it in they changed their tune -pardon the pun- and wouldn't even touch it. After I convinced them that I was okay with paying outside of warranty they made me sign a paper that their work wasn't guaranteed, they're not liable, blah, blah, blah. I just got the feeling that they still wanted nothing to do with it so I pulled it out of there and brought it to a reputable independent shop but so far they can't find the cause.
Been without my truck going on six weeks now because it just sat at the shop so long before anybody could look at it.
 

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My 2015 had a 5v problem. WAY different than your alerts, all mine were Fuel Pressure, Water In Fuel alerts. New PCM flashed with the "As built file"...good to go.

Yes, I had to return my "old" PCM back to stock, let the tech swap in the new PCM, he flashed it, I loaded up the tuning files. No cost to me as under warranty.
 

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The EPA threatens the shop with fines if they work on a vehicle that has been modified. The shop is supposed to return the system to the factory setup at the owners expense, or face sharp fines. Some shops overlook the regulations, but if they get caught it could mean the go out of business.
 

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Discussion Starter · #11 ·
The EPA threatens the shop with fines if they work on a vehicle that has been modified. The shop is supposed to return the system to the factory setup at the owners expense, or face sharp fines. Some shops overlook the regulations, but if they get caught it could mean the go out of business.
Yeah that makes sense, I get it. But I never would have brought it there in the first place if they hadn't told me they weren't as strict about it. Plus, I'm in SC which is pretty lax so didn't expect the push-back.
 

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Every "emissions training" I have went to has put emphasis on "you must return the system to factory" at the beginning of each class
I have the papers on the wall all the way to tier 4 final -- at least in Case-IH equipment
Cant wait until they require tier 5, ...LoL
 

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EPA should be disbanded, they have done good in the past, but no longer

look up the progression of the levels of "emissions" in engines

They are focused on NOx and that is way down in modern engines, but CO is way up
you can run your new diesel in your garage and not even smell the diesel stink
but you will die from CO poisoning
 

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Discussion Starter · #17 ·
Sooooo, after being down for six weeks, in limp mode, throwing P06A6, P0193, P0532 and P0335 codes, fuel pressure was spiking at 31,000 psi at idle, 5V Ref shorting out. Nobody could figure it out.
Turned out to be a bad crankshaft position sensor. A 20-minute fix after they spent a week crawling around chasing wires.
Hope this helps someone having the same issue. Per another forum, two other fellow 6.7 owners had the same issue and same codes. Theirs turned out to be a replacement of the fuel system from bad gas, and the other was a couple of weak batteries causing it, even though the batteries were testing fine. 🤷‍♂️
As always, thanks for the help Fellas.

Now just need to figure out how to set some time aside to replace the auxiliary water pump which they found to be bone-dry while under the hood.
Certainly seems to be a LOT of issues for a truck with only 9500 miles on her!
Stay safe out there.
 

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Glad you got it sorted

they should have started with disconnecting each sensor on the 5 volt line and watching the ref voltage
would have found the crank sensor a lot quicker -- I suppose maybe they will know better, next time
 

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Discussion Starter · #19 ·
Glad you got it sorted

they should have started with disconnecting each sensor on the 5 volt line and watching the ref voltage
would have found the crank sensor a lot quicker -- I suppose maybe they will know better, next time
I know, right. I've never had an issue with 5V before else I would have suggested the same thing, but, as you say...next time.
 

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Now just need to figure out how to set some time aside to replace the auxiliary water pump which they found to be bone-dry while under the hood.
Ummmm.....did you buy this truck brand new?? You do know there's a second degas bottle for the secondary coolant that is easily viewed to show the coolant level.
 
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