Let me see if I have this straight: You installed lights on the SIDE of the rig, which you wish to flash to indicate that you are considering a turn or lane change?
Is this right (Yes Read on, No, skip to next reply)
The REAR turn signals, on most vehicles made in the USA (Euro imports are different) are also the brake lights, so they will come on with the brakes, 100% of the time so long as everything is working.. EURO style has 3 lights on each side on the rear, Tail light (red) Stop (Bright red) and turn (usually amber) but US uses just the two, brake/turn are the same bulb
Solution.. if that is your problem... Is to power the side turn signals off the FRONT turn signals. These normally ONLY flash when the vehicle is signaling a turn.
NOTE: on many vehicles (I think my Damon is one of 'em but I"m not sure) there are marker/turn signals on the front.. These are neat, and you may find LED's won't replace them. Here is why
LED's (Depending on how they are built) are polarity sensitive, that is if you take the standard bayonet type base, like a 1156, the TIP must be POSITIVE or no light (You could for a few cents, add a full wave bridge to the assembly and fix that) (You can do it outboard too, if you need part numbers and diagrams ask)
But the marker/turn lamps hook between the PARKING LIGHT hot and the TURN SIGNAL hot on the front bulbs
IF you have the parking lights on, they "Ground" via the turn signals and glow
If you then signal a turn, when the flasher sends power to the lamps, the side light shuts off (since both leads are now hot)
IF you have the parking lights OFF, then they ground the other way, through the parking light elements, and when you send power to the turn signal they glow.
Real neat, and easy to hook up too, but LED's may not work without help there.
Home is where I park it!