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GMC Forum: Check Trailer Wiring warning
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Old 06-03-2018, 09:08 PM
redenbacher redenbacher is offline
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Location: Indiana
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Default Check Trailer Wiring warning

In 2014, I ordered a 2015 GMC Sierra to be my main vehicle and tow my travel trailer. It was ordered with the trailer tow package with max towing, integrated trailer brake controller, trailer mirrors, etc. All was good for the first two years. In September 2017, we went on a long trip to South Dakota and Wyoming. During the trip, we encountered almost constant problems with the trailer brakes becoming non-functional. The issue was very intermittent (off, on, off, on, etc.). The warning that displays is "Check Trailer Wiring" and then when braking returns, it displays "Trailer Connected". In Custer, SD, we took it to a local RV repair facility and they failed to find an issue. The issue is very serious as we lose the ability to use the trailer brakes. When returning home, we took it to the local GMC dealer (still under warranty). They failed to locate an issue and could not replicate it. We took the trailer to a repair facility and they went from front to back and found no issues.

A few months ago, a slightly different issue occurred (no trailer connected). This warning said "Service Trailer Brake" and the dealer was able to find a service bulletin to replace the switch (in the dash). We thought the problem was solved. Now our first camping trip of the year and the original Check Trailer Wiring (with loss of brakes) is still there. We have checked fuses, 7-pin connector and the entire trailer for issues. We are at a loss. The truck in now out of warranty. Thoughts?
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Old 06-07-2018, 07:37 PM
98trck 98trck is offline
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Join Date: Feb 2011
Location: Chandler Az
Posts: 248

it sounds to me that the circuit breaker has become weak and needs replacing
is the circuit breaker in the system the correct amperage ?
if the amperage is too low the breaker will heat up and disconnect, cool off and reconnect and do it again and again ( off,on,off,on,etc)
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brake, sierra 1500, trailer, wiring
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