With so many potential reasons for your RC car not to respond to throttle, I’ve put this Top 10 list together which I hope will help identify your specific problem.
These are the most common causes of an unresponsive throttle. Advice for each individual cause follows throughout the article.
- Your basic set up is incorrect
- Transmitter/Radio failure
- Battery failure
- Throttle servo failure
- Damaged servo wires
- The ESC is not calibrated
- Motor failure
- Your gears are out of alignment
- Optidrive switched your throttle servo off
- Incompatible transmitter and receiver combination
So let’s start with the basics and move on from there, I’ve tried my best to list these possible causes in order from most common to least.
- Your Basic Set Up Is Incorrect
I know receiving this basic advice may feel a bit insulting but anyone can accidentally have their frequency on the wrong channel without noticing. The idea here is to double-check every basic aspect of your set-up before going through a whole lot of higher-level troubleshooting when it may be a simple, easy fix.
Check the basics:
- Make sure the transmitter and RC are both switched on and have power running through them.
- Check your battery health.
- When you turn on your radio, make sure you’re not touching the trigger in any way. This can change the neutral point and confuse the receiver.
- Check on the backside of your radio for the reverse function switch, your throttle is usually channel two and the switch should be in the forward position.
- Check your throttle trim position which should be in the neutral position or in the position in which you originally set it to be.
- Check your antennas and make sure to extend them to the max if they do extend. Make sure they’re not touching any metal parts of your RC. Check them for any damage.
- Check that your vehicle and transmitter are both on the correct frequency to match up with each other.
- Check your fuel level to make sure it’s sufficient. Check your fuel pipes for any problems like kinks or blockages.
Now that you’ve checked all the basics, let’s move on to other possible causes.
- Transmitter/Radio Failure
Try swapping the throttle and steering servo plugs around on the RC. If the RC now accelerates with no steering then you can identify the transmitter as the problem. If there is still no throttle control and you can activate steering with your trigger, your throttle servo has most likely failed.
(Links to Amazon)
See my guide to RC channels here
If you have another compatible transmitter or can borrow one from a friend you can check if the transmitter is at fault without swapping servo wires on the RC. If you still have no throttle response with a fully functional transmitter then you can check the other causes of throttle failure on this list. It’s not your radio.
- Battery Failure
Make sure that your batteries are properly charged or test your RC with different batteries to see if that solves the problem. You can have your batteries tested by a technician before replacing them just to be certain.
Here’s how you can make your new batteries last longer and perform optimally:
- Always keep an eye on your batteries while you’re charging them.
- If you have Low-Voltage Detection, when using your LiPo battery, always have it switched on.
- If your batteries are swollen, melted, or damaged in any way, stop using them and replace them.
- Don’t charge LiPo batteries using a NiMH charger.
- Make sure to disconnect the battery from the ESC after you’ve used your RC.
- Charge your batteries in a fireproof container and on a non-flammable surface like cement.
- Throttle Servo Failure
Your throttle servo might not be plugged in properly or the servo itself may be broken.
- Check the servo plugs on the RC and plug them into the correct channel if you find them to be loose.
- If both servo plugs in the receiver are plugged in correctly, swap the plugs around and check if the same servo still doesn’t work. If the throttle servo still doesn’t work with the plugs reversed and the steering servo works with your trigger, then the throttle servo probably needs to be replaced.
- Damaged Servo Wires
Corroded, damaged, or loose wires could stop your throttle from responding.
- Check to see if there’s any corrosion on your servo wiring, this is normally caused by water getting inside.
- Loose wires from the motor can stop your RC throttle from responding, check and make sure they’re plugged in firmly.
- Inspect the wiring and check for any physical damage.
The good news is, if the servo wires are corroded or damaged, they can be repaired or replaced very inexpensively.
- The Esc Is Not Calibrated
The calibration of your ESC is a process of telling your car where neutral, full throttle, and maximum breaks are in relation to your transmitter. Once this is done, your RC will know exactly how much to accelerate or brake according to how far you move the controls.
If the calibration is out the RC might think that your throttle is in neutral while it’s actually on full-throttle position on the radio.
Refer to your operating manual to perform an ESC calibration, in most cases the “all at once” calibration will work perfectly but if that doesn’t get your RC moving, you can follow the manual step-by-step instructions.
- Motor Failure
Your RC motor can fail due to overheating, exceeding the max RPM range, severe crashes, vibrations, and some other causes.
You can test the motor with a different ESC and see if it works to know if you need to replace the motor or not.
(Links to Amazon)
If you’re comfortable opening the motor up and checking the ball bearings and magnets, you can do this now.
- To check if your bearings are still ok, just feel them out by turning them manually. When rotating the bearing with your fingers, there shouldn’t be any scratching or irregular bumps. It should make smooth consistent rotations.
- Check to make sure there aren’t any cracked magnets inside your motor.
- Check your magnets to make sure none of them are out of alignment with the others. If any of the magnets are moving in position, they will need to be securely glued in again.
- Your Gears Are Out Of Alignment
You may need to tighten up your pinion gear and realign it with the spur gear. However, if the gears are stripped you will have to replace them. A sign that they’re stripped or not aligned is if you hear a rattling/grinding sound when accelerating but the car isn’t moving forward.
- Optidrive Switched Your Throttle Servo Off
A red light on the Optidrive indicates a fault, this can shut down power to your throttle servo.
A red light indicator will glow in your RC if the Optidrives failsafe is active. The Optidrive can cut power to the throttle servos if the connection with the transmitter is lost or if the batteries aren’t adequately charged. Check your manual to see which specific failsafe features apply to your Optidrive to try and identify the problem.
- Incompatible Transmitter And Receiver Combination
Your receiver may not be compatible with your transmitter/radio.
- Check your compatibilities on both units and if they’re incompatible, you’ll have to replace one.
- If you’re trying to power your brushless SCT with an all-in-one ESC, it won’t work because it’s a one-speed (full out) type for smaller brushed motors.
There’s definitely a lot of reasons why your RC car might not be responding to throttle but these were the most common in my opinion. Most RC enthusiasts enjoy going through troubleshooting steps like this to learn more about their hobby. If you aren’t one of those people that enjoy troubleshooting or if you are like most people who just don’t have the time, take your RC into a hobby shop and have them take a look at it. With years of experience, hobby shop technicians will identify the problems and come up with solutions much quicker than you can.
I hope this article helped you in some way, if it did, please have a look at some of my other content as well.