Check Your On/Off Switches.
Sure, it might be embarrassing, but sometimes the problem is something as simple as not turning on both the transmitter (if it has a switch - some toys might not) and the RC vehicle. On some RCs you might even need a flashlight to clearly see which direction is on and which is off. Always check this first. And if simply turning on the switch doesn't work, be sure you have the switches in the off position before poking around inside your RC.
Replace the Batteries
The batteries are often at the root of many RC problems. Not running at all, running very slowly, or even stopping suddenly can be battery-related.
- Missing batteries. Check the RC and transmitter.
- Installed wrong. Make sure the batteries are in the right slots, facing the right direction, and completely seated in their little slots.
- Old batteries. Try some fresh batteries. Or if you're using some cheap brand, try a different brand. If using a battery pack, make sure it is fully and properly charged.
- Corrosion. If the vehicle has been sitting for a long time or the battery compartment has been exposed to moisture and air there could be some corrosion. In addition to replacing the batteries, clean the battery contacts.
A nitro RC can be an intricate and finicky piece of equipment. Before you start messing with engine settings, check the fuel tank. Is there fuel? Is it fresh? Is there a kink in the fuel line? If a quick visual inspection doesn't reveal a simple solution, then you may need to do a complete fuel system check. It's not difficult but it takes more time.
Use the Right Transmitter and Frequency
If it's an RC toy, make sure you have the correct transmitter. If you have a lot of RCs it can be easy to mix them up. If you bought the RC second-hand, the seller might have given you the wrong transmitter. Look for the frequency label on both the transmitter and the vehicle (often somewhere on the bottom, perhaps near the on/off switch or near the battery compartment. They should both be the same (such as 27MHz or 49MHz, etc.). If you have the wrong transmitter, you'll need to obtain the correct one.
For hobby-grade RCs, check the crystal in the transmitter and in the receiver on the vehicle. Make sure you have matched set. If you have another set you can use, try them.
If the RC has a telescoping antenna on the transmitter (or vehicle), be sure it is fully extended. While this probably wouldn't keep the RC from running at all, it could limit your range or cause it to run erratically.
Make sure the receiver antenna on your RC is properly installed, not twisted or broken, not touching metal parts inside the RC, and not dragging on the ground.
Test Your Servos
One sign that the problem is in your servos is if the RC responds only to some commands from the transmitter but not others -- for example the wheels will turn but it won't move forward. Try unplugging your servos from the receiver and plugging them into a receiver that you know is working (be sure to match the frequency of the receiver and transmitter). If the RC still doesn't respond then your servos, not the receiver or transmitter, may need repair or replacement. If you don't feel comfortable messing with the internal parts or don't have a known working receiver handy, try taking the RC to a hobby shop or RC club and ask for a little testing help.
Reconnect Your Wiring
Loose or broken wires can result in a host of problems. If steering works but the RC won't move, it could be from a loose wire from the motor. Lack of steering could signal a loose wire to the steering servo. If the RC doesn't appear to be getting power at all and you know the batteries are good, it could be a loose or disconnected wire from the battery pack or battery compartment that's causing the problem. Reattaching loose connections or resoldering wires (a bit more involved) may fix the problem.
Reset Your Gears
Repair a Broken Steering Arm
If the RC runs but it wobbles you may have broken a steering arm. Look inside for a long strip of plastic (like the tie rods on a real car) near the front wheels. Is one broken? You could replace it with a piece of stiff wire (like a coat hanger).