Chadw90

Yes I have. Battery voltage at brakes with controller on 10. once the trailer battery was fully charged, the brake voltage remains the same, but amperage drops through the floor. I can pull 10 different models of new trailer out of the lineup (we sell trailers at my work) or 10 used trailers, all the same until i put the diode inline. try to explain voltage vs amperage to a dealership auto mechanic is like trying to explain colors of the leaves in fall to a color blind person. Just doesn’t resonate lol. Not sure why something like a trailer brake controller needs to be over engineered by running it through it’s own logic controller, what was wrong with 12V direct battery wire to brake controller to brakes.

Magnet brakes here too. Electric hydraulic discs would be cool though

Get what you pay for I guess. Should have bought the Denali Ultimate for $130,000k CAD. Shame on me for buying the poverty AT4 for $106,000 lol. I should have kept my 2017, enough technology to keep you happy and not enough to have little gremlins like this. Id be tempted to go back to a 2017-2019 if I could find some gem that was just a sunday truck and low miles.

My problem was/is different than yours i guess. Yours is disconnecting, mine is dropping amperage as it seeing the trailer battery reach almost 13v’s. Once I put the diode inline, it prevented back-feeding and tricked the truck. My symptoms were strong brakes at the start and once the battery got charged up, Id have to turn the brake controller to 10 to get it to slightly grab the brakes. Most people wouldnt notice as they dont periodically just check their brakes along the trip. The symptoms are same as brake fade, but it happens with every trailer of all configurations. Like you, Im not impressed. When I go to buy a new truck, if GM hasnt rectified this, I may entertain a Ford, possibly a (gulp) Dodge.

On the 12v wire. I bought a short extension cord, opened it up and installed a diode inline on the 12v wire

Bilstein 5100’s on my last two Duramax trucks(2017 silverado 2500 & 2023 sierra at4 2500). Night and day difference. Much more planted feeling. No dancing on washboard and no hopping on the highway.

Found that it is an aux fill port. The fitting is open on the bottom side. No straw/tube attached.

I am thinking probably not l, just due to the fact that it has a sealed cap on it. Not a vent of any sort. My dodge had an auxiliary pickup tube there so you didn’t have to install a draw tube. Was hoping thats what this is for but would like to know before dropping the tank or pulling the bed

Does anyone know what the third tube into the sending unit on the L5P is for? My truck is a 2023 GMC 2500. There is two quick connect lines (supply & return) and then a third one with a quick connect cap on it. I am looking to install a Webasto or Espar and am wondering if thats a draw straw into the tank Thanks

If thats your case, the tech running the alignment machine isnt doing it right. When they perform a wheel alignment, they have to align the front end to compensate for the crown in the road. 2% slope is an average for watershed. If they didnt dial in the front end to compensate for this, your truck would have a heavy pull to the shoulder. Either way, mine is clocked to the right at 1 o'clock in the right hand lane and about 2 o’clock in the left hand lane. When you let go of the steering wheel, ideally the truck should have a very very slight/gentle pull to the shoulder in the event of an unresponsive driver, the ditch is the safest. Everyone likes a straight driving truck, you usually have to ask for that, this one is straight like its on a set of train tracks, just the steering wheel off.

My 2023 gets an alignment every oil change due to the wheel being off center. Its like it is on a trip meter. At roughly 8000kms, its off to either the right at 1 o’clock or left at 11 o’clock. To and from work i have option A which is two different highways(one south, one east) or option B which is one east and then south. Doesnt matter which way i take there or back, same issue. let go of the steering wheel and it tracks perfectly, no pull to the right or left, just the steering wheel off. No abnormal tire wear, or vibrations. Does this regardless which tires are on(i have a set of winter tires on factory rims and my all terrains on factory rims). I even ditched the OEM Hankook MT2 tires that came on the truck stock. We have tried max tire pressure for the truck, bumped it down to 50psi, back up to 60 front 65 rear. Nothing helps. They do the alignment and its bang on for about 6-7000kms and by 8-9000kms its at 11 or 1. At 10,000kms, i take it in for oil change and alignment

I did my first two oil changes at 5000kms just to get any break in junk out. Didnt let my truck idle, and put a load behind it as often as i could. Even towed a skidsteer around when it wasnt needed. i just rolled over 40,000kms a few weeks ago and fuel economy has gotten better, even with winter diesel up here in Saskatchewan. I have a Banks idash for monitoring and regens have gone from 900kms-1000kms between regen to 1200kms - 1350kms now. might be a coincidence but seems like it all happened at 40,000kms. i also change my fuel filter at every 10,000kms regardless what the monitor says, engine oil and filter also at every 10,000kms with rotella t6 5w40. like anything, good maintenance yields a good truck.

Interesting. This makes sense. One bad rotor out of four could definitely be the issue here and honestly a relief. I was thinking if one brake line or caliper had a defect sending too much fluid to the right rear or something like that. Try to explain or have that diagnosed by the dealer lol. I will just toss a set of new rotors on if the dealer wont under warranty being this has been an ongoing issue

I have a pulsating when braking too. They turned my rotors at 26,000kms free of charge due to my trailer brake module taking since new to diagnose. Just figured rotors warped due to not having any trailer brakes and big loads. but just put my winter wheels on tonight and right rear has 39 thou runout, left rear 4 thou. Didnt bother measuring the front as the right rear is enough to cause it. No steering wheel shake. Calipers slide nicely on the pins, pads are worn evenly. I will ask the dealer tomorrow but i would imagine a new set of rotors are going to be on my dime. But curious on why they warped again. I do not brake hard like the OP lol. I use my exhaust brake and drive as conservative as possible, Im always on the quest for the best mileage possible.

Ya i get what you’re meaning here. My big trailer, i have a truck end plug wired to a solar panel to keep the batteries topped up while its parked, so my brake fault is immediate when i hook up. My small enclosed has a trailer brake battery maintainer, my truck runs at 14ish volts when driving, so 13.3 with a diode in line, still enough to trickle charge that little battery. Brakes work great when i first hook up and within 15mins, they are weak. It mimics brake fade. I unplugged the battery today and they worked 100% all day. All other trailers that i tow for work, i dont care if they get a rapid charge or not. I could tow work trailers 5 times a week and it be different trailers each time. We just grab one out of the new line up and toss a dealer plate on it. this is where i plan to get a 3’ extension cable and put a diode in line, just for those trailer that I dont own. what DC to DC converter did you use. Id put one on each of my personal trailers.

BG DFC Plus here. 4oz per 100L. We use it in our bulk tanks. Also use their other products in our fuel system cleaner tool. Ive heard Hotshots is good stuff. Seeing is believing, and the ball bearing test is the true test. Ive seen what I thought were great products, do absolutely nothing. BG, stanadyne and hotshots all passed the test. BUT you can overdose with these. We have seen too much conditioner cause a jelly in the tank and filters. As mentioned in above post, a little goes a long ways.

Same here. Installed the diode on my big enclosed trailer, works great. But have the issue on my small trailer. I can install a diode here too but this isnt the solution. I often pull different trailers for work. I cant be installing diodes in every trailer. After a couple months of observing, my trailer brakes work as expected for the first little bit. It is until the trailer battery gets fully charged from the truck that it is causing an issue backfeeding to the truck. Can go from having aggressive lock up braking at gain 6 to just a slight hardly noticeable drag on gain 10. im thinking about an extension cable and dissecting it and installing a diode in it. Then my diode would be in the cable that i can use on every trailer. Ultimately there needs to be a diode on the truck side.

Mine were warped just as you described. Started to notice it at 20,000kms. I had trailer brake issues and after in/out of the dealer over the course of a couple months, they replaced some modules and machined my rotors at 26,000kms, we figured this was due to the truck having to do all the braking. But im starting to notice the pulsating again at 35,000kms. My fuel mileage is too good to have brakes dragging. Im convinced that it is just poor quality rotors. this is my 26th vehicle, first with warped rotors.

I had air lift bags w/compressor in my 2017. I thought they were the best thing since sliced bread….until i tool them out and drove it to the dealer to trade it in. Couldn’t believe how much smoother it was with the bags out. I ran the minimum of 5psi with them in. i put timbren’s in this new truck. They work great. 10,500lb skidsteer on a bumper hitch and the truck sits level. Ride unloaded and loaded are both great. Cheap and easy install.

That would leave you with essentially like a .65 to 9.5 gain setting in relation to the voltage drop? That would work fine with me. Im now on gain setting 6 for my camper. Will just need to bump it up a half or so to be relatable to what it was before.

Same…diode is the answer. BUT, lets get crafty and put it on the back side of the connector and then its a fix for every trailer rather than just the ones you own. I pull fleet trailers from work often and we rotate them out of the fleet as early as every week or two(pending the salesmen are kicking a$$). Just need to find the time to put the truck up on the lift and get it done. should we the consumers have to do this though, hard no. GM should utilize some AI and gather information from these forums to come up with a fix. if it weren’t for people like all of you, there would be very little solutions out there. Hats off to the wealth of knowledge on this forum.

Your first line of this comment says enough about your knowledge of the most modern diesel engine. FT4 = Final Tier 4 Emissions. Aka, DEF And camper, are you on the right post? Or maybe Im mistaken and the OP camper is full of lead? Combined GVW of 34,640lbs would be like a 26,000lb camper. Keep in mind a run of the mill bumper hitch 35’ camper is 8500lbs. Anyways. Back to school… what does it have to do with working a diesel hard? your claim of more diesel burnt = more DEF. This is false. DEF consumption isnt a direct correlation to fuel consumption. A 20mpg truck is not going to burn half as much DEF as a 10mpg truck. It is all relative to load and temp A truck sitting on site at idle all day long is going to sip fuel and chug DEF. Theres a measurable line to obtain optimal DEF and fuel consumption. Extreme light load and low exhaust temp will result in extremely high DEF consumption and frequent regens. Medium load and exhaust temps result in a favourable fuel and DEF consumption with fewer regens Extremely high load and higher exhaust temps result in moderate DEF consumption and fewer regens. distance/mpg mean absolutely nothing when measuring DEF consumption. Exhaust temp and load is all that matters. Light load is <600F Medium load >600F but <1050F High load >1050F Melting holes in pistons is >1600F To the OP, your DEF consumption is fine for what you are pulling. You are not using 3x the rated spec of DEF as to what the above post is referencing of 2% and 7.5%. These percentages are dismissible as you are not using the truck in an “as per spec” application. Loaded, you are using EVERYTHING that truck has, which is awesome and very rarely seen. Some would say that is big d!ckin it for sure. A new vehicle purchase is going to yield you the same results and a pissed off pocket book. the Ford uses marginally less DEF, but not worth the ick of owning a Ford.

I would have to disagree to some extent here. In R&D yes you are correct, but R&D does not replicate real world customer applications. Reality is that there is a large volume of customers that should not own a FT4 diesel. Short commutes, lots of stop and go, idling, aborted regens due to short commutes etc will contribute to more DEF consumption than light-medium load long distance driving. New FT4 diesel like to be hot and worked. When I am trying to explain to someone how the adverse effects of city driving has on a diesel, i reference a tuned up 24v pre emissions Cummins. Every green light, every corner, every start up, that thing gives a huff of black smoke. Now add an exhaust filter in there that has a job to trap that soot, every time you accelerate, it is soot loading that filter. In the SCR, more DEF is now required to keep the chemical reaction up to keep the exiting nox levels down. if you are cruising down the highway with a light to medium load and achieving 14mpg, you are going to burn less DEF and experience fewer passive regens and active regens than you will driving around town or those short commutes and achieving that same 14mpg. BUT in the R&D world where they fold the mirrors in on road tests for optimal fuel economy, yes you are very correct. More diesel = more def. But hell, park the truck in the garage and you will use zero diesel, zero def. It’s not much of a theory. I have a customer that is in landscaping and snow removal. The owner runs one skidsteer and son runs another. Identical twin machines. Same parking lots moving snow. The owner burns less fuel, more DEF and has more frequent parked regens. Many complaints and service calls and I finally went and pulled load profiles on the units myself thinking we have an issue Owners unit’s RPM graph is like a roller coaster. He operates with the fixed rpm dial off and utilizes the foot throttle for his RPM and rarely sees 80% RPM or higher. He “baby’s” his unit. Son runs his fixed throttle WFO all the time. Burns more fuel, less DEF and has almost zero parked regens. The dad complains that the boy is hard on iron, but he is running that unit in the most efficient way. Hot and hard. Keeps the exhaust system clean as a whistle. Owner now runs his at 90% ish RPM and has alleviated all of his problems. No more idle to hard acceleration has solves his emissions complaints.

When I pull my 30’ deck over enclosed on our mountain trip, over the 1650 miles, i burn 165 gal of fuel and use about 7.5 gal of DEF. How much do these DEF tanks hold? i put 1 jug in when I get to 1/4 tank. I always run on the bottom half just because Im from Saskatchewan and subject to 6 or more months of freezing temps. Half a tank is easier to thaw out than a full tank. 6.2 mpg out of nearly 35,000lbs running down the highway is quite impressive i must say. I still dont agree with the towing capacity of a pickup towing an electric brake trailer. Electric brakes fail “off”, so in the event of an emergency and brakes are not working, that truck with 4 disc brakes must be able to stop that load…its not happening. At least with a semi, failure on the brake circuit locks brakes on. Just my opinion though. But by the looks of it, my DEF usage is similar to yours? Im not concerned in the least bit. I prefer to use DEF and less frequent hard regens. i have a Banks I Dash monitor and when towing, i get 700 miles between active regens. When empty, im getting 500 miles between active regens. The truck isnt getting hot enough to keep a clean filter with DEF injection when empty.

Handle still functions fine. This is the first time i lifted it from the stowed position anyways lol