Sorry I haven't gotten back. My P3 will only apply the brakes a little bit even though I have the setting all the way up, unless I use the manual override. I have a 97 F350 Dually Powerstroke that I have checked and double checked all the wiring. I have the correct settings, walked thru the proper setting on the phone with them. I just sold my Travel Supreme and bought a Mobile Suites but haven't had a chance to try it out yet. I still have the last P3 they sent me and will give it a try on the Mobile Suites. It just didn't want to work very well on the Travel Supreme so I put a old Activator II in there. It worked very well, the higher the settings, the more brakes. Its not proportional like the P3 and can be very jerky if set to high. Thanks for all your reply's, when I finally run the Mobile Suites I'll report back. If it works good with that then the problem must have been in the Travel Supreme! Thanks again!