Brake Lights & Turn Signal Lights on when Brake Pedal is Pushed

[RC2018]

I have seen comments about this before but can't seem to get a firm handle on the root cause. In my 2003 Diplomat I am seeing both the Brake Lights and the Amber Turn Signal Lights every time I depress the Brake Pedal.
I assume its a ground problem but not sure. Can anyone offer their solution to this issue? Does anyone have a wiring diagram for 2003 Diplomat that would be willing to share?

I look forward to any help I can get.

[rmacdon61]

I would also assume a ground problem and start there.

[YC1]

Pull a tail light out so you can put a voltmeter on the wires.

On one side of the bulb you should see the highest voltage. That is, close to battery voltage when the pedal is pushed.

Then check the ground side of the bulb. You will likely see a small voltage.

Run a temporary ground wire for testing and connect it to that low voltage side. The light should get bright and your issue should go away unless you need to run more than one ground wire.

[clifford j]

I would not jump into a ground issue right away. I first would determine if any of the bulbs had an internal short (an internal cross )

CLIFFORD.

[CountryB]

This is a diagram for a 2005 Monaco. Might not be the exact same as your coach, but probably close.

When you say the amber turn signal lights are On with the brake lights - I assume your talking about the front turn signals (rear use the same bulbs as stop lights).

So the common place for a problem like this is in the Turn signal switch or in the Hazard warning switch.

What happens when you activate the Turn Signals (do both sides R & L flash when just one side should be on - or does that work normally)?

[vito.a]

Is your coach wired for trailer lights?
Another possibility is the trailer 3 to 2 tail light converter. Our coaches use separate turn signals from the brake lights, but most trailers use the brake light bulbs for both a turn signal and brake lights. To do this, they install a 3-2 converter. It may be bad or just wired incorrectly.
An example of a 3-2 converter.
https://www.amazon.com/56146-Powered...omotive&sr=1-6

[RC2018]

I will add a jumper to ground & see if that cures the issue. Thanks for the suggestion.
My coach is wired for a trailer so that also is something to look at. Thanks for the info. I'll reply after I investigate a little more.

Randy

[RC2018]

I have added ground wires and still not working correctly. I just ordered a new 3-2 wire converter. I assume the one on my coach has failed and is the root cause of the power feeding from the brake light circuit to the turn signal bulbs. Has anybody else had any experience with the 3-2 modulate converter going bad?