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 > New GMC 2500 Wont Engage Trailer Brakes

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BenK

SF BayArea

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Posted: 12/11/21 05:11pm Link  |  Quote  |  Print  |  Notify Moderator

Most manual lever actuation will bypass the logic circuit (controller) and send power to the trailer brake wire, but am assuming they are all the same in logic.

My P3 also bypasses the logic circuit and sends power to the trailer brake wire

Question: are the OEM integrated brake controllers manual lever variable or just on/off in function ?

Also, my P3 (stolen and have to purchase another soon) leads the TV brakes. Even in a panic jab at the TV brake pedal.

Once power has been sent to the trailer wire by the P3, the accelerometer in the P3 takes over to proportion the power sent to the trailer wire.

Of course factored by the preset, but if the accelerometer senses building G forces, it will meter out up to full power to the brake wire.

Can and have stopped the whole setup without ever pushing the TV brake pedal far enough to developer MC PSI (not freeway, but it could and take longer with just trailer brakes…which will have the P3’s accelerator send ever more power once it senses whatever G forces vs preset). Try that with any highly integrated brake controller that uses MC PSI as the determining sense.

If one of these integrated trailer brake controls also has a brake pedal light switch sense, then it might likewise be able to stop the whole setup without ever developing MC PSI, but to date, have not read of that

Nothing wrong with OEM integrated brake controllers. Just not for me and if I do purchase another TV and it has a highly integrated brake controller…I’ll continue to go with a P3


-Ben Picture of my rig
1996 GMC SLT Suburban 3/4 ton K3500/7.4L/4:1/+150Kmiles orig owner...
1980 Chevy Silverado C10/long bed/"BUILT" 5.7L/3:73/1 ton helper springs/+329Kmiles, bought it from dad...
1998 Mazda B2500 (1/2 ton) pickup, 2nd owner...
Praise Dyno Brake equiped and all have "nose bleed" braking!
Previous trucks/offroaders: 40's Jeep restored in mid 60's / 69 DuneBuggy (approx +1K lb: VW pan/200hpCorvair: eng, cam, dual carb'w velocity stacks'n 18" runners, 4spd transaxle) made myself from ground up / 1970 Toyota FJ40 / 1973 K5 Blazer (2dr Tahoe, 1 ton axles front/rear, +255K miles when sold it)...
Sold the boat (looking for another): Trophy with twin 150's...
51 cylinders in household, what's yours?...

MFL

Midwest

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Posted: 12/11/21 05:36pm Link  |  Quote  |  Print  |  Notify Moderator

Hey Ben, the P3 is a great unit, and I've used 4 different brake controllers, before having my current Ford IBC. All IBCs are not the same, and IMO, the Ford is top of heap.

To answer your question, my IBC manual lever is variable, from just a little, to locking the wheels. My IBC set on 5.5 of 10, will stop entire rig from towing speed, using manual lever, if I wanted, but no one wants heated trailer brakes, unnecessarily!

If you get a truck with IBC, especially a Ford, give the IBC a try Ben! Don't let old thinking hold you back! [emoticon]

Just don't ever throw away the P3!

Jerry





ktmrfs

Portland, Oregon

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Posted: 12/11/21 09:37pm Link  |  Quote  |  Print  |  Notify Moderator

BenK wrote:

Most manual lever actuation will bypass the logic circuit (controller) and send power to the trailer brake wire, but am assuming they are all the same in logic.

My P3 also bypasses the logic circuit and sends power to the trailer brake wire

Question: are the OEM integrated brake controllers manual lever variable or just on/off in function ?

Also, my P3 (stolen and have to purchase another soon) leads the TV brakes. Even in a panic jab at the TV brake pedal.

Once power has been sent to the trailer wire by the P3, the accelerometer in the P3 takes over to proportion the power sent to the trailer wire.

Of course factored by the preset, but if the accelerometer senses building G forces, it will meter out up to full power to the brake wire.

Can and have stopped the whole setup without ever pushing the TV brake pedal far enough to developer MC PSI (not freeway, but it could and take longer with just trailer brakes…which will have the P3’s accelerator send ever more power once it senses whatever G forces vs preset). Try that with any highly integrated brake controller that uses MC PSI as the determining sense.

If one of these integrated trailer brake controls also has a brake pedal light switch sense, then it might likewise be able to stop the whole setup without ever developing MC PSI, but to date, have not read of that

Nothing wrong with OEM integrated brake controllers. Just not for me and if I do purchase another TV and it has a highly integrated brake controller…I’ll continue to go with a P3


I had a P3 on my 2004 silverado. IMHO the GM IBC on our 2015 Denali is light years ahead and orders of magnitude better than the P3.
smoother, quicker acting, better modulation

As I mentioned in an earlier post I had to do a panic stop from 60mph ABS on full, truck and trailer stayed absolutely straight and trailer braking compared to the P3 was way better.


2011 Keystone Outback 295RE
2004 14' bikehauler with full living quarters
2015.5 Denali 4x4 CC/SB Duramax/Allison
2004.5 Silverado 4x4 CC/SB Duramax/Allison passed on to our Son!


aftermath

Washington State

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Posted: 12/12/21 08:31am Link  |  Quote  |  Print  |  Notify Moderator

Paroled, I have been where you are and I feel for you. Since the GMC crowd say their controlers are very good, I would fight with the company for a solution. You can even ask for a new truck if it gets to that point.

That said, I had a P2 controller on my first Tundra and it was great. I moved up(?) to a 2017 Tundra with a built in controller and it was terrible. It was a timed controller and after meeting with Toyota, writing letters and making phone calls they told me it had been tested and that it was performing to standards which was all true. I still had my controller, found an in dash bracket and You Tube video and installed it myself. It is still working and working well.


2017 Toyota Tundra, Double Cab, 5.7L V8
2006 Airstream 25 FB SE
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Grit dog

Black Diamond, WA

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Posted: 12/12/21 09:38am Link  |  Quote  |  Print  |  Notify Moderator

BenK wrote:

Most manual lever actuation will bypass the logic circuit (controller) and send power to the trailer brake wire, but am assuming they are all the same in logic.

My P3 also bypasses the logic circuit and sends power to the trailer brake wire

Question: are the OEM integrated brake controllers manual lever variable or just on/off in function ?

Also, my P3 (stolen and have to purchase another soon) leads the TV brakes. Even in a panic jab at the TV brake pedal.

Once power has been sent to the trailer wire by the P3, the accelerometer in the P3 takes over to proportion the power sent to the trailer wire.

Of course factored by the preset, but if the accelerometer senses building G forces, it will meter out up to full power to the brake wire.

Can and have stopped the whole setup without ever pushing the TV brake pedal far enough to developer MC PSI (not freeway, but it could and take longer with just trailer brakes…which will have the P3’s accelerator send ever more power once it senses whatever G forces vs preset). Try that with any highly integrated brake controller that uses MC PSI as the determining sense.

If one of these integrated trailer brake controls also has a brake pedal light switch sense, then it might likewise be able to stop the whole setup without ever developing MC PSI, but to date, have not read of that

Nothing wrong with OEM integrated brake controllers. Just not for me and if I do purchase another TV and it has a highly integrated brake controller…I’ll continue to go with a P3


I sometimes have to lol at statements like the last one! Such conviction!


2016 Ram 2500, MotorOps.ca EFIlive tuned, 5” turbo back, 6" lift on 37s
2017 Heartland Torque T29

Grit dog

Black Diamond, WA

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Posted: 12/12/21 09:43am Link  |  Quote  |  Print  |  Notify Moderator

OP, of course you can spend the time and money and get an aftermarket controller. It’s the easy thing to do if you’re the type who is afraid of confrontation.
Otherwise, it appears you have a lemon law case ripe for the picking or continue to demand it be repaired.
You have a bigger hammer in your hand than you think. You have a “safety” issue that is unresolved by a billion dollar company and their “defective” product.
Use all the ammo in your bin brotha. Don’t puss out and give in!

BenK

SF BayArea

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Posted: 12/12/21 11:11am Link  |  Quote  |  Print  |  Notify Moderator

MFL...Thanks for you comments and yup, at 73 and am older than most on this forum, but control logic isn't much different from when was designing controllers decades ago.

Yes, lots of the components are faster, more sensitive, and CHEAPER nowadays, but the logic/truth tables are about the same...albeit with many more variables tossed into the fray by having to integrate with everything.

Why know that some of these issues are founded in the time-outs designed into the logic tables. Also question how 'real-time' these OEM's software is and that is part of the time-outs know is happening in a real-time environment

So which did the designers/architects decide should have a higher order flag? The ABS? The traction control? The IBC? "Real-time" meaning that the computer deals with a high order flag before doing anything in the queue. 1st, 2nd, 3rd, etc flags are dealt with in that order. Then within 1st order flags, there are other hierarchical levels

Akin to the age-old relay race issues of my day.

IMHO, too close to a Rube Goldberg these IBC's. Simplicity of a separate controller appeals to me. If it flakes out, replacement is around $150 bucks and is a plug and play. Vs IBC requiring an engineer to diag properly with tooling that costs in the tens of thousand of bucks. Even then, they resort to replace & cross fingers it works.

IMHO, most folks who didn't like their P2/P3 didn't have them setup well and/or their TV's brake pedal switch isn't as sensitive as GM's, which only takes about <0.03" movement to 'click' on the TV's brake circuit.

Bottom line: found some rust on the roof of my 1996 Suburban, right next to the top windshield edge. Must have had something hit it & compromised the paint/galvanized coating. That might cost more than I'll wish to...but stuck wanting to build a HO 7.4L (miss the C2/L88). Stuff has been chipping away at that, as found out that GearVendors does NOT fit in a 1996 4x4 Suburban because the tranny tail housing is gone & replaced by the Xfr case.

Me Again

Sunbird(Wa)/snowbird(Az)

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Posted: 12/13/21 06:40am Link  |  Quote  |  Print  |  Notify Moderator

The engineer that redesigned the RAM IBC in 2015(maybe it was 2014) must have moved to GM. RAM had a good IBC however most users in around 2015 started complaining about these pulse width controllers verses older current varied ones. RAM's decreased braking as the vehicle slowed. I found running mine in Heavy Electric over hydraulic on my drum brake trailer worked better.


2021 F150 2.7 Ecoboost - Summer Home 2017 Bighorn 3575el. Can Am Spyder RT-L Chrome, Kawasaki KRX1000. Retired and enjoying it! RIP DW 07-05-2021


mkirsch

Rochester, NY

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Posted: 12/15/21 06:29am Link  |  Quote  |  Print  |  Notify Moderator

I agree. This is a warranty issue, a safety issue, a liability issue. Don't let them off the hook.

Heck I would not have taken the truck back when they said "can't fix it." I would say keep it until you fix it and give me a loaner in the meantime.

Maybe this is a myth and I'm too lazy to go look it up, but I think they're on strike two of the three strikes that the lemon law allows. If you bring the concern to them once more and they are unable/refuse to fix it, you've got a case.

Even these "highly integrated brake controllers" use an accelerometer to sense the deceleration of the vehicle and apply trailer brakes to match. It sounds to me like this part is faulty in your new truck.


Putting 10-ply tires on half ton trucks since aught-four.

mkirsch

Rochester, NY

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Posted: 12/15/21 06:31am Link  |  Quote  |  Print  |  Notify Moderator

Okay, I got less lazy and did a quick google. Here's a website that explains California lemon law:

https://www.lemonlaw.com/california-lemon-law.html

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