A wiring diagram is a streamlined standard pictorial depiction of an electric circuit. Answer: Of those 3 wires; one is on with your lights or always on - that's your running light. In most vehicles, the ground wires will be either brown or black. When you press the right button, a 12 V signal is fed to the TSSM on a W/BN wire or a W/V wire when you press the left button. Three wire setups allow the turn signal to operate as a running light when not active. Check the necessary things. If just one end is out, it's much more likely a feed wire is broken, or if both ends are out, a bad turn signal switch. Matt shows how to repair a broken or corroded ground wire for a 2007 Jeep Wrangler with a Horn and Right Turn Signal that has stopped working. JavaScript is disabled. Just picked up a 89 and I need help. If it still doesn’t work, you can also check to be sure if it’s a connection problem and not the wiri… The third wire is not crucial to the operation of your new turn signals if the original only has two wires. Mod links