Hey all. I figured I'd post this on here for those of you with 2015 Ram HD models.
Basically, some of use are having trouble get full power out of our trailer brakes. A pair of posters at http://www.ramforum.com/f119/brake_controller-71708/
ended up getting pushed into intersections by their trailers.
My tale is simpler. In August I borrowed my father's toy hauler. We hooked up and we're setting the gain on the brakes. He tows with a 2012 Ram 3500 and sets his gain to about 3.5. That was my starting point as well. Ended up at 6.5. He thought something was fishy because at 3.5 his grabs hard where at 6.5 mine was moderate. I just attributed this to my ITBM being set to light electric and his most have been on heavy.
So away I went. I didn't think much else of it... until I had my own trailer and was facing 10 miles of 5-8% downhill grade. I stop at the brake check area and set it to heavy electric 6, slide the bar over and give it some gas and I'm pulling the trailer without sliding the wheels. Cranked it up to 7.5 and they still didn't provide near enough resistance. Fortunately I'm a granny and just took it easy down the grade and didn't need them much.
I get back and start researching and find that other owners are having issues with their trailer brakes too. They work, just not real well. A few have been in to the dealer. Most run a quick diagnostic and say it's working as it should. One replaced the ITBM with no success. I got out my multimeter and checked voltages. On light electric on gain 10 and slider all the way over I was getting 8.3v at the 7pin. Heavy electric only 7.4v! I posted this and others had very similar results. This should be close to 12.5v!!!
Somebody found a thread on an airstream site with a 2015 Ram owner having the same issue. Dealer runs diagnostic and says it's ok. Customer insisted it is not, so they replaced the ITBM from a 2015 on the lot. Like the other guy, this did nothing to help. Dealer insists his trailer brakes are not set up properly so he calls the Airstream dealer and they have him bring in his truck. They too find around 8v at the pin. In minutes they isolated the problem to a connector from the wiring to the 7pin. A contact inside the connector was not making good contact. 5 min with a pick and some dielectric grease and he had over 11v and his trailer brakes work great now!!
IF you have 2015 Ram 2500 or 3500 check to see if you can lock up the trailer brakes with the slider at 20mph or so. If not, you likely have the same issue we are fighting.