Integrated trailer brakes not producing output - Chevy and GMC Duramax Diesel Forum
07.5-10 LMM Duramax Powertrain Discussion of components that are directly involved in the power production and all that is needed to get and keep the truck moving . Engine , Transmission, Etc.

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post #1 of 3 (permalink) Old 11-25-2019, 01:06 PM Thread Starter
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Location: Lone Oak, TX
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Integrated trailer brakes not producing output

I have recently acquired a 2008 LMM dually and the integrated trailer brakes are not functioning. I have no fault message, which is what most of the research I have found says occurs when they are not functioning and I am able to adjust the gain on the brakes but when connected to the trailer, I have no output. I am not very skilled at tracking these types of issues down so I am looking into some insight. I have purchased the relay that is under the spare tire but have not replaced that as of yet, plan on that this evening. No wires I can see in the back near the trailer connector have been cut or spliced but I did find an old brake controller stuffed under the drivers side dash but the wires to it were not connected. Any insight would be appreciated. Thanks in advance.

2007 Classic LBZ 2500 LT 4x4 EC LB 244+k, 5" cat back exhaust, EFI Live, all illumination to LED, otherwise all stock

2008 LMM CC Dually LWB 3500 LTZ 4x4 154k, Rebuilt turbo, up pipe, EGR delete. H&S tune. No DPF or cat.
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post #2 of 3 (permalink) Old 11-25-2019, 01:40 PM
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Heard plenty of complaints on the initial ITB controller... My 2013 didn't work... I bypassed it w a Prodigy P3... Not entirely uncommon...

Easy and simple... Instructions and videos on youtube or E

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post #3 of 3 (permalink) Old 11-25-2019, 06:37 PM
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It could be a bad trailer Brake Control Relay, which is located above the spare tire on the drivers side of the frame. A relatively common, known issue.

Id certainly check that before I bought an after market controller.

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Also, since you just recently got the truck, this thread may be of interest and help:

2008 Silverado 2500HD CCSB LTZ Diesel
FASS 95 Lift Pump (with Baldwin filters), Edge Insight CTS Monitor on a Windshield Mount, Nicktane Fuel Filter Adapter w/ CAT 306-9199 UHE tertiary fuel filter, Bilstein 5100 Stock Height, Bushwacker Bed Rail Caps, AMP Research Bedstep, Fumoto oil drain valve, Dorman PS Oil cooler, Pioneer AVIC 7200NEX GPS/Stereo, Air Lift LoadLifter 5000 Air Bags.
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