Section 102(2) in The Central Motor Vehicles Rules, 1989
(2)[ On all vehicles other than motor cycles, [the intention to stop the vehicle (other than construction equipment [and the combined harvester] [Sub-Rule (2) substituted by GSR 214(E), dated 18.3.1999 (w.e.f. 18.3.1999).] vehicle having hydrostatic brakes)] shall be indicated by two electrical stop lamps which shall be red in colour and shall be fitted one on each left and right-hand sides at the rear of the vehicle. The stop lamps shall light up on the actuation of the service brake control. In the case of motor cycle, the intention to stop the vehicle shall be indicated by one stop lamp at the rear which shall light up on the actuation of the control operating the brakes on the rear wheels.]
