# How to build the ELEGOO Smart Robot Car V4, step by step The ELEGOO Smart Robot Car V4.0 is a four wheel camera car you drive from your phone. This guide breaks the build into small steps, each with its own drawing, the exact screws and the mistake most people make on that step. Updated 2026-10-27. HTML version with a drawing for every step: https://robotsforthat.com/robot-kits/elegoo-smart-robot-car-v4-build-guide/ Free step by step build tool with an AI photo coach: https://robotsforthat.com/lab/build/elegoo-car-v4/steps/ ## Short answer Plan for 2 to 3 hours. Build the motors, add the line sensor, mount the boards and battery, build the camera and eye tower, wire it up, close the frame and add the wheels. No soldering and no coding. ## Facts - Kit: ELEGOO Smart Robot Car Kit V4.0 - Price: About $66 to $80 - Build time: 2 to 3 hours - Steps: 29 - Difficulty: Beginner - Coding needed: None - Age: Maker says 12+. Younger kids build it great with a parent. ## What is in the box - Brain: UNO R3 board and expansion board. Runs the car. Its program comes already loaded. - Eyes: Camera and ultrasonic sensor on a servo. Streams video to your phone and spots walls. - Wheels: 4 motors and 4 tires. Four wheel drive on a two deck frame. - Senses: Line tracking and motion sensor. Follows a black line and knows when it tilts. - Power: Rechargeable battery box. Charges by USB. No AA batteries. - You add: A phone. For the EleRobot app. The remote works without it. ## Part 1: Get ready (2 steps, about 10 minutes) ### Step 1: Sort the parts by bag Open the box on a big table. Keep each small bag closed for now. Every bag has a label like FOR MOTOR or FOR CAMERA, and each step tells you which bag to open. Tip: Start charging the battery box now with the USB cable. It needs about 2 hours. Check: Bags laid out, still closed. Common mistake: Pouring every bag into one pile. The screws look alike and are hard to sort later. ### Step 2: Peel the film off both plates The two black plates have a thin protective film on each side. Peel it all off before you build. Parts: Bottom plate, Top plate Check: Both plates are shiny black, no film left. Common mistake: Leaving the film on. It traps screws and looks cloudy later. ## Part 2: Motors (2 steps, about 20 minutes) ### Step 3: Fix a block to each motor Open the bag FOR MOTOR. Put a small aluminium block against a motor and push two M3x30 screws through the motor and the block. Add an M3 nut on each. Do all four motors. Parts: 4 motors, 4 aluminium blocks, 8 M3x30 screws, 8 M3 nuts Check: 4 motors, each with a silver block. Common mistake: Using short screws. These are the long M3x30 ones. ### Step 4: Screw the motors onto the bottom plate Put the bottom plate flat. Fix each motor's block to a corner of the plate with two M3x10 screws from below. Point the motor shafts outward and the wires toward the middle. Parts: Bottom plate, 8 M3x10 screws Check: 4 motors under the plate corners. All shafts point outward. Common mistake: Pointing a shaft inward. The wheel will not fit. ## Part 3: Line sensor (1 steps, about 10 minutes) ### Step 5: Mount the line sensor under the front Open the bag FOR UNO, LINE TRACKING. Put four white spacer pillars between the plate and the black line tracking board, under the front of the bottom plate. Fix with four M3x14 screws and four M3 nuts. The three sensors face the floor. Parts: Line tracking board, 4 white spacer pillars, 4 M3x14 screws, 4 M3 nuts Check: Sensor board under the front, sensors facing down. Common mistake: Mounting it on top of the plate. It has to see the floor. ## Part 4: Brain and battery (4 steps, about 20 minutes) ### Step 6: Add the motion sensor to the board Open the bag FOR CELL BOX, TIRES, GY-521. Fix the small blue GY-521 sensor onto the expansion board with the M3x11 copper pillar and two M3x5 flat head screws. Parts: GY-521 sensor, Expansion board, 1 M3x11 copper pillar, 2 M3x5 screws Check: Small blue board standing on a gold pillar. Common mistake: Overtightening. The small board cracks easily. ### Step 7: Fix the UNO board to the top plate Fix the UNO board on the top plate with three white spacer pillars, three M3x14 screws and three M3 nuts. Parts: UNO board, Top plate, 3 white spacer pillars, 3 M3x14 screws, 3 M3 nuts Check: UNO board flat on its spacers. Common mistake: Skipping the white spacers. Metal parts under the board can cause a short. ### Step 8: Press the expansion board on top Line up every pin of the expansion board with the UNO sockets and press it straight down. Parts: Expansion board Tip: Look along the side before pressing. Check: No pins showing outside the sockets. Common mistake: Pressing at an angle. One bent pin stops the car working. ### Step 9: Fix the battery box Fix the black battery box on the top plate behind the boards with two M3x12 screws and two M3 nuts. Parts: Battery box, 2 M3x12 screws, 2 M3 nuts Check: Battery box held firm at the back. Common mistake: Putting the box over the board. Its power switch must stay easy to reach. ## Part 5: Camera and eyes (5 steps, about 35 minutes) ### Step 10: Fix the camera to its bracket Open the bag FOR CAMERA. Screw two M2x6 copper pillars to the black camera bracket with M2x4 screws, then fix the camera board on the pillars with two more M2x4 screws. Plug in one 4 wire cable. Parts: Camera board, Camera bracket, 2 M2x6 copper pillars, 4 M2x4 screws, 4 wire cable Check: Camera board on the bracket, lens facing out. 4 wire cable plugged in. Common mistake: Mounting the camera upside down. The lens goes at the top. ### Step 11: Fix the servo to the small plate Open the bag FOR ULTRASONIC. Put the blue servo with its white holder through the small black plate. Fix it with two M2x10 screws and two M2 nuts. Parts: Servo with white holder, Small black plate, 2 M2x10 screws, 2 M2 nuts Check: Servo held under the holder plate. Common mistake: Twisting the servo arm by hand. It sets the eyes straight later. ### Step 12: Fix the ultrasonic eyes Fix the blue ultrasonic sensor (the part with two round eyes) to the front of the white holder with two M1.6x8 screws and two M1.6 nuts. Parts: Ultrasonic sensor, 2 M1.6x8 screws, 2 M1.6 nuts Check: Two eyes facing forward. Common mistake: Using the long M1.6x16 screws. Those are for the next step. ### Step 13: Add the camera behind the eyes Fix the camera bracket to the back of the white holder with two M2x6 copper pillars, two M1.6x16 screws and two M1.6 nuts. Parts: 2 M2x6 copper pillars, 2 M1.6x16 screws, 2 M1.6 nuts Check: Camera stands above the eyes, both face forward. Common mistake: Facing the camera backward. Lens and eyes must look the same way. ### Step 14: Mount the sensor tower at the front Fix the whole tower to the front of the top plate with three M3x10 screws and three M3 nuts. Parts: 3 M3x10 screws, 3 M3 nuts Check: Tower stands straight at the front. Common mistake: Mounting it at the back. The eyes go over the narrow front. ## Part 6: Wiring and frame (6 steps, about 35 minutes) ### Step 15: Plug in the servo Plug the servo's 3 wire plug into the port marked Servo1 on the expansion board. Brown wire to GND. Parts: Servo cable Check: Servo plug in Servo1. Brown wire on GND. Common mistake: Plugging it in backwards. Check the wire colors match the pin labels. ### Step 16: Plug in the eyes and the camera Connect the ultrasonic sensor to its port with a 4 wire cable, then plug the camera cable into the camera port. Parts: 4 wire cable Check: Both 4 wire cables clicked in. Common mistake: Swapping the two plugs. Check the port labels on the board. ### Step 17: Add the six tall posts Open the bag FOR ACRYLIC BASEPLATE. Screw six tall M3x40 gold pillars onto the bottom plate with six M3x10 screws from below. Parts: 6 M3x40 gold pillars, 6 M3x10 screws Check: Six posts standing straight. Common mistake: Mixing up pillar sizes. These are the tallest gold ones. ### Step 18: Plug in the four motors Plug each motor into its port: left front M1, right front M2, right rear M3, left rear M4. Parts: Motor cables Tip: Front means the end with the eyes. Check: All 4 motor plugs in the right ports. Common mistake: Plugging a motor into the wrong port. The car spins or drives backward. ### Step 19: Plug in the line sensor Connect the line tracking board under the car to its port with the 5 wire cable. Parts: 5 wire cable Check: 5 wire cable clicked in at both ends. Common mistake: Letting the cable hang low. It will drag on the floor. ### Step 20: Close the car Place the top plate on the six posts and fix it with six M3x10 screws. Parts: 6 M3x10 screws Check: Top plate firm on all six posts. No wire pinched between plates. Common mistake: Trapping a wire between the posts and the plate. ## Part 7: Wheels (1 steps, about 10 minutes) ### Step 21: Put on the four wheels Push a wheel onto each motor shaft, then fix it with an M2x25 self tapping screw through the center. Parts: 4 tires, 4 M2x25 screws Check: 4 wheels on, each spins freely. Common mistake: Forcing the wheel at an angle. Line up the flat side of the shaft first. ## Part 8: Drive it (8 steps, about 20 minutes) ### Step 22: Check every plug Compare your car with the finished car. Every cable plugged in, nothing touching the wheels. Check: No loose cables. Wheels spin without touching wires. Common mistake: Skipping this check. A loose plug is the top reason a part does not work. ### Step 23: Switch it on Slide the power switch on the battery box to ON. The status light on the board comes on. Check: Status light is on. Common mistake: Battery not charged. A red light means it is low. ### Step 24: Drive with the remote Pull the plastic tab out of the remote. Use the arrows to drive. Press 1 for line following, 2 for obstacle avoiding, 3 for follow me. Parts: Remote control Check: The car drives with the arrows. Common mistake: Leaving the plastic tab in the remote. Nothing happens. ### Step 25: Get the app On your phone, install the EleRobot app from the App Store or Google Play. Check: EleRobot app installed. Common mistake: Installing an old Elegoo app. Look for EleRobot. ### Step 26: Switch to camera mode On the expansion board, slide the small switch from upload to cam. Check: Switch is on cam. Common mistake: Leaving it on upload. The app cannot connect. ### Step 27: Join the car's Wi-Fi In your phone's Wi-Fi settings, join the network named ELEGOO followed by numbers. When the phone says No internet, stay connected. Check: Phone shows ELEGOO Wi-Fi connected. Common mistake: Letting the phone switch back to home Wi-Fi. ### Step 28: Drive from your phone Open EleRobot, pick Smart Robot Car, tap Remote Control and OK. Use the round joystick, then try FPV mode to drive using the camera view. Check: The car moves with the joystick. You can see the camera view. Common mistake: Pushing the joystick all the way. Start with small pushes. ### Step 29: Let it drive itself In the app, try Obstacle Avoidance: put it on the floor and watch it turn away from walls. Then try Line Tracking on a black tape line. Tip: If it misses the line, use keys 4, 5 and 6 on the remote to tune the sensor. Check: It turns away from walls on its own. Common mistake: Testing line tracking on a dark floor. Use black tape on a light floor. ## Troubleshooting ### The app will not connect Why: The board switch is on upload, or the phone left the car's Wi-Fi. 1. Slide the small switch on the expansion board to cam. 2. Join the ELEGOO Wi-Fi again and stay connected when it says No internet. 3. In the app, tap the link icon in the top right. Comes from step 26. ### No camera picture Why: The camera cable is loose or the camera board is upside down. 1. Check the 4 wire camera cable is clicked in at both ends. 2. Check the lens sits at the top of the bracket. 3. Switch off, switch on and reconnect. Comes from step 16. ### The car spins in circles or drives backward Why: Motor plugs are in the wrong ports. 1. Left front M1, right front M2, right rear M3, left rear M4. 2. Front is the end with the eyes. Comes from step 18. ### The remote does nothing Why: The plastic tab is still in the remote, or the battery is low. 1. Pull the clear plastic tab out of the remote. 2. Point it at the car from close up. 3. Charge the car if the status light is red. Comes from step 24. ### It misses the line Why: The line sensor needs contrast and the right threshold. 1. Use black tape on a light floor. 2. Press 4 or 6 on the remote to tune the sensor, 5 to reset. 3. Check the 5 wire cable is in at both ends. Comes from step 29. ### Nothing turns on Why: The battery is flat or switched off. 1. Slide the battery box switch to ON. 2. Charge it with USB for about 2 hours. The light is green while charging. Comes from step 23. ### A wheel wobbles or falls off Why: The wheel went on at an angle or the screw is missing. 1. Pull the wheel off and line up the flat side of the shaft. 2. Fix it with the M2x25 screw through the center. Comes from step 21. ### The eyes point sideways Why: The servo plug is backwards or the servo arm was turned by hand. 1. Check the servo plug is in Servo1 with brown on GND. 2. Switch off and on so the servo centers itself. Comes from step 15. ## Sources - [ELEGOO Smart Robot Car V4.0 assembly tutorial (PDF)](https://drive.google.com/drive/folders/1hACczXN-CzxTFHsO3yrLW7QJ1HhHiZJJ) - [ELEGOO Smart Robot Car V4.0 downloads](https://www.elegoo.com/blogs/arduino-projects/elegoo-smart-robot-car-kit-v4-0-tutorial) ELEGOO Smart Robot Car V4 is a trademark of ELEGOO. robotsforthat is not affiliated with ELEGOO.