04 Monaco Diplomat Brake light/ML issue

[gyoder]

I have a 2004 Monaco Diplomat and when I hit my brake the ML / Taillights come on as well, has anyone else had this to happen?

[8.3Oilbuner]

Hi Gyoder; Never had it happen to me, but it sounds like a grounding issue. Somehow you are getting a feed back thru the other lights. Check your grounds. Need to follow the ground wires out and see where they are attached. Rear end of these coaches get a lot of water & stuff thrown up into the back of the cap assembly. On my 01 Windsor I had to clean some grounds for another situation I had. Just my thoughts on your situation!

[YC1]

I agree with a bad ground. Grab a voltmeter and test the hot and and ground side of one of the lights in question. If you have full 12 volts on one side and a smaller voltage on the ground side, you have a ground issue and can chase it down or just build a new ground wire.