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10-19-2019, 01:03 PM
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#1
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Senior Member
Join Date: Feb 2014
Location: Young America MN
Posts: 372
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GMC or Keystone problem?
This is totally new for us. Have been towing this trailer (Alpine) with the same GMC 3500 for about 8 years. All of a sudden when I go to shut of the truck it keeps running even with the key removed from the ignition and does so until we disconnect the trailer plug and it shuts down. We discovered this while getting everything ready to head south for the winter.
Anyone have this happen or even have ideas what is feeding back to keep the ruck running? Hate to spend the whole winter having to unplug to shut the truck off but may not have the time to run it down.
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39 foot Forest River Vengeance dragged by GMC 3500.
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10-19-2019, 02:34 PM
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#2
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Senior Member
Join Date: Mar 2014
Location: Mountain Home, Idaho
Posts: 3,009
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You indicated your GMC is 8 years old so guessing it’s a 2011 model Duramax? If you’ve got the integrated brake control from the factory I’d be looking at the brake control module as suspect...
This has a constant signal voltage always back to 7 way wire harness plug ..
The Alpine is most likely not causing the issue and you could verify the total resistance seen at the Alpine male 7 way plug
An active voltage to the ECM is what’s keeping the engine running
All four brake magenta are in parallel and if you measure male 7 way plug on pins 1 and 2 you are looking for around 14 ish ohms
If this reads correctly then it eliminates any issues with brake and ground wires to Alpine
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2007 GMC Classic club cab 4x4 Duramax LBZ
2014 Alpine 3010 RE. 34 foot fifth wheel
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10-19-2019, 03:04 PM
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#3
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Senior Member
Join Date: Feb 2014
Location: Young America MN
Posts: 372
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Chuck, doesn't matter but it's a 2008 GMC Duramax that we have towed that particular trailer with for 8 years. Will have to take some readings and check into that module. Thanks.
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39 foot Forest River Vengeance dragged by GMC 3500.
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10-19-2019, 08:02 PM
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#4
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Senior Member
Join Date: Mar 2014
Location: Mountain Home, Idaho
Posts: 3,009
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Another suggestion is on the Alpine side... looking forward from rear of pinbox you should see a metal junction box. Take cover off that box and verify all connections in junction box are good.
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2007 GMC Classic club cab 4x4 Duramax LBZ
2014 Alpine 3010 RE. 34 foot fifth wheel
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10-19-2019, 08:15 PM
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#5
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Senior Member
Join Date: Mar 2014
Location: Mountain Home, Idaho
Posts: 3,009
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I’d also remove, clean, and reseat theses connections on control module and relay
__________________
2007 GMC Classic club cab 4x4 Duramax LBZ
2014 Alpine 3010 RE. 34 foot fifth wheel
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10-20-2019, 02:59 AM
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#6
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Senior Member
Join Date: Feb 2017
Location: Dade City
Posts: 1,039
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Does the whole truck stay alive when turning off the key or just the engine stay running and the dash and other things go dark (off)?
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10-20-2019, 10:09 AM
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#7
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Senior Member
Join Date: Mar 2015
Location: Southeastern Connectiut
Posts: 1,306
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For a quick check I'd hook up to a neighbors 7 way plug and see if the problem goes away. Lot quicker and easier than disturbing your wiring.
Good Luck,
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Pull Toy
Steve & Jan, Ava & Emma (Mini Schnauzers):
2016 F350 Lariat 4X4 Powerstroke CC/SB "PULLTOY V"
2013 Alpine 3535RE "MAGIC CARPET IV"
Proud Navy Vet!
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10-21-2019, 03:58 AM
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#8
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Senior Member
Join Date: Oct 2018
Location: Sacramento
Posts: 1,005
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Is your truck Diesel? I don't know about your model year, but I think I've read that when the engine needs to complete some cycle - I don't remember what they are called - the engine can remain running until complete. Perhaps it's a turbo cool-down cycle?
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2022 Cedar Creek Champagne 38EL - "Big Bertha"
2019 GMC Sierra 3500 Denali HD 6.6L Duramax TD, CC, 4WD, DRW - "Mr. Beefy"
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10-21-2019, 06:32 AM
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#9
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Senior Member
Join Date: Mar 2014
Location: Mountain Home, Idaho
Posts: 3,009
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No turbo cool down cycle on Duramax...Regen cycle on newer models with DEF system.
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2007 GMC Classic club cab 4x4 Duramax LBZ
2014 Alpine 3010 RE. 34 foot fifth wheel
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10-21-2019, 07:04 AM
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#10
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Site Team
Join Date: Oct 2011
Location: Joppa, MD
Posts: 11,741
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Quote:
Originally Posted by Pull Toy
For a quick check I'd hook up to a neighbors 7 way plug and see if the problem goes away. Lot quicker and easier than disturbing your wiring.
Good Luck,
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This or find an RV dealer close by. Explain that you are having an issue and don't know if it's the trailer or not. Ask them if you can connect the plug from one of their units (doesn't matter which one) before you bring in the camper. They may let you.
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Marshall
2012 Laredo 303 TG
2010 F250 LT Super Cab, long bed, 4X4, 6.4 Turbo Diesel
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10-21-2019, 07:08 AM
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#11
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Senior Member
Join Date: Oct 2018
Location: Sacramento
Posts: 1,005
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For the OP: Is it true that you don't even have to tow the trailer? You can just plug in the trailer umbilical, start the truck and then turn off/remove the key and the truck will continue to run?
__________________
2022 Cedar Creek Champagne 38EL - "Big Bertha"
2019 GMC Sierra 3500 Denali HD 6.6L Duramax TD, CC, 4WD, DRW - "Mr. Beefy"
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10-21-2019, 09:20 AM
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#12
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Senior Member
Join Date: Dec 2017
Location: Calgary, Alberta, Canada
Posts: 306
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A quick question. If you leave it running without the key for around 20 seconds ish does it stop? Could be a short in the ignition switch between ignition and retained power? Usually if you shut off truck power stays on for a bout 10 or 20 seconds. Or until you open a door. If this was the case it could be feeding ignition power over to the ignition side? Hope that helps.
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2020 GMC 3500 Denali Dually Duramax 6.6
2013 Fuzion 342 ToyHauler (Ours)
2011 Harley Davidson Streetglide custom (Mine)
2012 Harley Davidson TriGlide (Trike) (Hers)
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10-21-2019, 09:26 AM
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#13
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Senior Member
Join Date: Dec 2017
Location: Calgary, Alberta, Canada
Posts: 306
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__________________
2020 GMC 3500 Denali Dually Duramax 6.6
2013 Fuzion 342 ToyHauler (Ours)
2011 Harley Davidson Streetglide custom (Mine)
2012 Harley Davidson TriGlide (Trike) (Hers)
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10-21-2019, 12:33 PM
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#14
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Senior Member
Join Date: Feb 2014
Location: Young America MN
Posts: 372
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Just an update without having done anything since the truck is in the shop for wheels and tires and getting it ready for winter travel.
I let it run for 5 minutes with ignition off and key out of the truck. At the end of 5 minutes pulled the 7 plug and truck stopped. Several times. 5th wheel was not hooked to the truck, just the wiring.
Truck back by Thursday and time for #1 son to get his Ice Castle out of storage so I'll hook to it and check it out as well as the other suggestions.
Thanks.
PS will certainly post when I actually find the problem.
__________________
39 foot Forest River Vengeance dragged by GMC 3500.
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10-30-2019, 03:00 PM
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#15
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Senior Member
Join Date: Feb 2014
Location: Young America MN
Posts: 372
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Don't have much so far. It's been in the 30s when average is mid 50s so not doing a lot of checking b4 traveling. Will have to unplug to stop the truck until we hit warm climates and have time. So far have only plugged into my son's ice castle and truck shut off just fine. Have not done more than that yet other than plugging the trailer in and it still runs until unplugged. Might be December or at least late November b4 i can check farther. Did shut of the 5th wheel 12v disconnect but did not disconnect the batteries completely.
__________________
39 foot Forest River Vengeance dragged by GMC 3500.
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11-18-2019, 03:34 PM
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#16
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Senior Member
Join Date: Feb 2014
Location: Young America MN
Posts: 372
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Not really an update BUT, tried at least 10 times while still in cold MN and it did the same thing. Tried my son's ice castle and it shut off just fine. Left for Biloxi keeping the problem. First stop still freezing Iowa weather and it had to be unplugged to turn off the truck. Missouri stop in cold still same. Next 2 stops in warmer weather and it's back to working right.
If I fund anything or it happens again I will post again.
????????????????
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11-19-2019, 08:44 AM
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#17
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Senior Member
Join Date: Mar 2014
Location: Mountain Home, Idaho
Posts: 3,009
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Great to hear an update. If I read your last right you plugged into sons RV and and shut off ok. Sounds like tis in your RV wiring and could be many things
I’d out an ohm meter on 7 way plug on RV end and measure total resistance of all 4 magnets from those two pins .. if it’s way over 13.5 ohms or way less than you’ve got an issue with a magnet
They are all wired in parallel and you will read total resistance of all 4 at once. Won’t isolate your issue to where but may point to area of issue.
I’d also recheck the junction box inside pin box compartment for lousy wire connections.
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