Operation Instruction: 1.Turn off the vehicle's engine. 2.Connect the black clip to the negative terminal of the vehicle battery, connect the red clip to the positive terminal of the battery. 3.Locate the fuel injector which you want to test, then remove the electrical cable from this injector and connect the tester's two pulse output terminals to the electrical connector of this injector. 4.Press the MODE SET key to select the desired pulse mode, the display shows the current pulse mode. Injector Tester Specification: Power Supply:12V vehicle battery Operation Environment:0-40C,relative humidity Less than 80% Storage Environment:-10C ~50C, relative humidity Less than 85% Test Cable Length: 41.5cm/ 16.3 inches Product Size:147x82x29mm Explanations for the 4 Modes: Mode1: the tester will output 1 pulse, whose pulse width is about 250ms. Mode 2: the tester will output 50 pulses, every pulse's pulse width is about 7ms. Mode 3: the tester will output 100 pulses, every pulse's pulse width is about 3.5ms. Mode 4: the tester will output continuously at the rate of 50 pulses per about 1450ms, every pulse's pulse width is about 7ms. At any time, you can press the PULSE key again to stop outputting pluse. 5. After you have the desired pulse mode, press the PULSE key. The tester outputs pulse(s) to the injector under test, the pulse signal indicator will light as indication. Material:ABS colour:black Package Contents: 1 * Injector Tester Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.