jmurraywv

I have searched and have seen way too many issues with the service trailer brake system. I changed the relay and it "seemed" to fix my issue initially but it came back. What I have discovered is it seems fine for a variable period but what seems to trigger it is applying the brakes. It isn't necessarily right after I start the truck and drive it for a short distance but this morning it happened after about 20 minutes and coming to a stop off the interstate. I noticed it come on after I drove it after work coming down a hill from the parking lot so only a few minutes of driving. I hate to throw parts at a problem and hope it resolves it even if they aren't "expensive" but I'm thinking at this point it might be the brake pedal switch or the master cylinder sensor. I'm looking for someone who may have had the same condition or more knowledgeable than me who can give me something specific to test. Before I changed the relay, I checked the voltage from the master cylinder sensor and was getting decent voltage but I assume since it is variable, mine might be failing under heavier pressure? Also, this is all happening without a trailer connected.