A light emitting diode, LED, running light, comprising: a plurality of series coupled LED block cells (402a..e, 404a..e); a current sink); each of the plurality of LED block cells (402a..e, 404a..e); comprising an LED; and a bypass circuit (404a..e) coupled between a cathode of the LED and the current sink, wherein the bypass circuit (404a..e) is configured to decouple the cathode of the LED from the current sink when a voltage at the anode of the LED is greater than a certain voltage value, wherein the bypass circuit (404a..e) comprises: a first transistor coupled between the cathode of the LED and the current sink; and characterised in that the bypass circuit (404a..e) further comprises: a zener diode coupled between the anode of the LED and one end of a first resistor having another end thereof coupled to a power supply common; and a second transistor having an input coupled to a junction of the zener diode and the first resistor, and an output coupled to an input of the first transistor, wherein a voltage across the first resistor turns on the second transistor which then turns off the first transistor, thereby decoupling the cathode of the LED from the current sink, wherein the first and second transistors (504, 514) are preferably selected from the group consisting of bipolar junction transistor and field effect transistor. a plurality of series coupled LED block cells (402a..e, 404a..e); a current sink); each of the plurality of LED block cells (402a..e, 404a..e); comprising an LED; and a bypass circuit (404a..e) coupled between a cathode of the LED and the current sink, wherein the bypass circuit (404a..e) is configured to decouple the cathode of the LED from the current sink when a voltage at the anode of the LED is greater than a certain voltage value, wherein the bypass circuit (404a..e) comprises: a first transistor coupled between the cathode of the LED and the current sink; and characterised in that the bypass circuit (404a..e) further comprises: a zener diode coupled between the anode of the LED and one end of a first resistor having another end thereof coupled to a power supply common; and a second transistor having an input coupled to a junction of the zener diode and the first resistor, and an output coupled to an input of the first transistor, wherein a voltage across the first resistor turns on the second transistor which then turns off the first transistor, thereby decoupling the cathode of the LED from the current sink, wherein the first and second transistors (504, 514) are preferably selected from the group consisting of bipolar junction transistor and field effect transistor. an LED; and a bypass circuit (404a..e) coupled between a cathode of the LED and the current sink, wherein the bypass circuit (404a..e) is configured to decouple the cathode of the LED from the current sink when a voltage at the anode of the LED is greater than a certain voltage value, wherein the bypass circuit (404a..e) comprises: a first transistor coupled between the cathode of the LED and the current sink; and characterised in that the bypass circuit (404a..e) further comprises: a zener diode coupled between the anode of the LED and one end of a first resistor having another end thereof coupled to a power supply common; and a second transistor having an input coupled to a junction of the zener diode and the first resistor, and an output coupled to an input of the first transistor, wherein a voltage across the first resistor turns on the second transistor which then turns off the first transistor, thereby decoupling the cathode of the LED from the current sink, wherein the first and second transistors (504, 514) are preferably selected from the group consisting of bipolar junction transistor and field effect transistor. a zener diode coupled between the anode of the LED and one end of a first resistor having another end thereof coupled to a power supply common; and a second transistor having an input coupled to a junction of the zener diode and the first resistor, and an output coupled to an input of the first transistor, wherein a voltage across the first resistor turns on the second transistor which then turns off the first transistor, thereby decoupling the cathode of the LED from the current sink, wherein the first and second transistors (504, 514) are preferably selected from the group consisting of bipolar junction transistor and field effect transistor.