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pcm1959's avatar
pcm1959
Explorer II
Sep 06, 2017

GM Duramax - NO Trailer Brakes

I have a 2013 HD with the factory integrated trailer brake controller. Today when I plugged in the fiver, NO brakes.
The DIC shows nothing but the the gain set point. I can adjust the gain up and down. No messages such as "trailer connected or trailer disconnect" nor any chimes.
There has been an occasion when I plug-in in the umbilical cord that I have had to jiggle it or unplug it and re-plug it to get a connection but that is rare. Once its connected I have never had an issue. In addition I do have the in-bed plug as well as the one near the bumper but neither would work today. I looked underneath but all the wiring looks fine.
All of the trailer lights work - turn signals and brake lights.
I connected a tester to the vehicle end plug to test the function of each blade. When I tested the brake blade, there was a very, very slight pulsing of the test meter needle even without pushing the brake pedal OR the manual brake control on the ITBC. Pressing the brake pedal or manual control made no change.
I do have e/h Dexter disc brakes on the fiver with the HBA-Cam adapter for the disc brakes. I checked all the wiring connections and they all looked fine.
I pulled the trailer on Friday with no issue. The trailer and truck were parked until today and now in 3 days, now no brakes.
Am I correct in that this issue is on the truck end since I am not getting any output with the test meter when testing the "brake Blade" on the vehicle end?
I checked 3 fuses......number 19 ITBC, 58 Stud 2, and 63 Stud 1. Number 19 is ok. The other 2 are fuses I'm not familiar with, however, compared to the others like it there was no difference in their appearance.
I plugged-in the RV again and no change. No messages at all on the DIC. Plugging and un-plugging the umbilical cord creates no messages or chimes.
Thanks, Phil
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  • 2003silverado's avatar
    2003silverado
    Explorer II
    Sep 07, 2017
    KD4UPL Makes a really good point. I have a trailer with bad brake wiring and all lights work but the truck won't recognize the trailer as being connected. When my fuse 63 blew, I had a continual "service trailer brake message" on my dic whether or not the trailer was connected. When you get through Irma if you have access to a friends truck you might plug your trailer into it and at that point you could determine which is the problem.

    Our best wishes and prayers are with you and the state of Florida.
  • KD4UPL's avatar
    KD4UPL
    Explorer II
    Sep 07, 2017
    I would guess an open connection somewhere. It could be on the truck but I would suspect the trailer first. Trailer wiring I've seen is usually not as tidy and well supported and fastened as most new truck wiring.
    On my '15 Chevy the display says trailer connected and trailer disconnected when you plug and unplug IF the trailer brakes are functional. If they aren't then it doesn't know. If the trailer brake wiring develops a short it gives me the message "Service trailer brakes". Since you don't have that I suspect an open, not a short.
  • pcm1959's avatar
    pcm1959
    Explorer II
    Sep 07, 2017
    2003silverado wrote:
    When my fuse 63 blew it exhibited the same symptoms as yours, to my eyes it looked good but when I put an ohm meter on it, it was no good. When I looked through a magnifying glass I could see the crack in the copper.

    I'm not trying to beat a dead horse, but the naked eye can't always determine a failed fuse


    I appreciate that. As I mentioned, not being familiar with that type of fuse, It appeared normal. I will check it more carefully or perhaps just replace it.
    I have To deal with Irma now but will post what my results are.
    Thanks! Phil
  • 2003silverado's avatar
    2003silverado
    Explorer II
    Sep 07, 2017
    When my fuse 63 blew it exhibited the same symptoms as yours, to my eyes it looked good but when I put an ohm meter on it, it was no good. When I looked through a magnifying glass I could see the crack in the copper.

    I'm not trying to beat a dead horse, but the naked eye can't always determine a failed fuse.

    My truck is a 2012. You could swap fuses with a similar one to see if it makes a difference..
  • pcm1959's avatar
    pcm1959
    Explorer II
    Sep 07, 2017
    2003silverado wrote:
    Check fuse number 63 in your under hood fuse box. It is a 30 amp large square fuse.


    "I checked 3 fuses......number 19 ITBC, 58 Stud 2, and 63 Stud 1. Number 19 is ok. The other 2 are fuses I'm not familiar with, however, compared to the others like it there was no difference in their appearance".

    Thanks....did that already.
  • 2003silverado's avatar
    2003silverado
    Explorer II
    Sep 07, 2017
    Check fuse number 63 in your under hood fuse box. It is a 30 amp large square fuse.
  • pcm1959's avatar
    pcm1959
    Explorer II
    Sep 06, 2017
    salem wrote:
    IIRC, my '16 Chevy doesn't show a connect icon on the DIC. It just shows the gain. It moves when I step on the brake. I'm assuming yours is the same. If it wasn't connected you would not be showing that. It's too darned hot to run out and hook up the 5'er and verify that so maybe someone else can jump in.:) On my old truck, which had a Tekonsha unit in it, a large "C" would show in the window when hooked up.


    Must have changed on the 2016. My 2011 and this 2013 gives messages anytime its connected OR disconnected. In addition, a graph is displayed in the DIC as the brakes are applied either with the pedal or manually.
    I am getting nothing just as if its never been connected. All functions of the plug are working (all functions of lights including brake lights) except the brakes.
  • pcm1959's avatar
    pcm1959
    Explorer II
    Sep 06, 2017
    Mine says "Trailer connected or Trailer disconnected anytime you plug it in or unplug it. Doing either also produces a chime. I am getting no message or chime when I plug in the trailer OR unplug it.
    Pressing the pedal or using the manual lever produces nothing on the display like it normally would not does it produce any output to the brake blade on the truck end plug.
  • salem's avatar
    salem
    Explorer
    Sep 06, 2017
    IIRC, my '16 Chevy doesn't show a connect icon on the DIC. It just shows the gain. It moves when I step on the brake. I'm assuming yours is the same. If it wasn't connected you would not be showing that. It's too darned hot to run out and hook up the 5'er and verify that so maybe someone else can jump in.:) On my old truck, which had a Tekonsha unit in it, a large "C" would show in the window when hooked up.
  • ScottG's avatar
    ScottG
    Nomad
    Sep 06, 2017
    The signal you get with no trailer connected is normal for a brake controllers output. It doesn't allow power flow unless it detects a load.

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