Over the past few weeks my 4Runner will occasionally behave weirdly when pressing on its gas pedal. When it happens, it is usually when at a standstill and then pressing the gas pedal to move forward doesn’t do anything, not even rev the engine up. The vehicle just idles forward, which is very dangerous if you are in an intersection and can’t move anywhere! (Note that the 4Runner starts and idles just fine.) This can be due to two possible problems. Either the Vehicle Stability Control (VSC) system needs to be recalibrated (described in this post), or the throttle body is dirty and is sticking shut (I describe how to clean it in a different post).
If your vehicle has these same symptoms, then you can perform fixes for both of the issues I mentioned above. The VSC recalibration is free and I will describe it in this post. I found a solution to this problem at http://www.yotatech.com/f2/01-02-4runner-how-zero-point-calibrate-your-vsc-system-203498/, but their solution is not entirely correct so I’m writing this post to explain what I did. The solution to the throttle body cleaning can be found at http://www.top4runners.com/ja/cleantb.html.
The cause of the problem is that the Vehicle Stability Control (VSC), which is responsible for the traction control, needs to be calibrated. It can go out of calibration for various reasons – for example, from any vehicle repair, maintenance, modifications or aging that cause the vehicle to not sit level anymore. The result is that the 4Runner thinks that you are skidding or sliding when you really aren’t (because the non-level tilt of the vehicle doesn’t match what the wheels’ rotations should be for that tilt, or something like that I think).
Performing the Fix
This fix involves recalibrating the VSC system, so it is important to get your vehicle as level as you can make it. To do this, first make sure that your tires are all inflated to their proper level (I highly recommend the Viair 70P air compressor). Second, park the vehicle on a level surface. Third, open the driver-side window, get out of the vehicle, and close the door – you can’t be sitting in the vehicle or it won’t be level.
Next make sure that the vehicle is off. Open the hood. Locate the Diagnostic port on the driver’s side of the engine and open it (circled in green in picture at right). You will see a bunch of metal terminals. If you look in the lid you will see that it has labeled them for you. We will be using the E1 and TS terminals, but don’t do anything with them yet.
Reach in the driver’s window and turn the key to the "ON" position. (Do not actually start the vehicle, just turn it to "ON" so that the battery is running the vehicle’s electronics.) Look at the dash board and wait for the "VSC TRAC" light to go out.
Use the aforementioned piece of wire to repeatedly short together the E1 and TS terminals at least 4 times within 8 seconds. Remove the wire and look in the driver’s window again and you will see the "VSC TRAC" dash light on again. After 5 or 6 seconds it will turn off, and then if you wait a couple more seconds it will start blinking rapidly.
Now turn off the ignition.
Turn the key back to the "ON" position (but don’t start the car) and wait for the "VSC TRAC" light to go off.
HERE IS THE KEY PART missing from the other tutorial linked above. The last thing to do is:
- Turn off the ignition.
- Put the wire back in the E1 and TS terminals, but this time do not repeatedly short it, just put it in and leave it in.
- Turn the key back to "ON" and wait for the "VSC TRAC" light to start blinking very quickly.
- Turn off the ignition.
- Remove the wire.
- Start the car (you can get in it now).
The other tutorial that I previously linked to said that these steps I just mentioned were optional, but they are not – they must be performed. If you skip this step then when you start driving the vehicle then the "VSC OFF" light will turn on while you press on the gas and then the light won’t turn off. For some reason performing these steps prevents that.
You can now close the Diagnostic port lid, close the hood, get in the vehicle and take it for a drive. Make sure that neither the "VSC OFF" nor the "VSC TRAC" lights turn on during your short drive (unless you actually spin out somewhere or if you have locked your rear differential).
I just performed this fix, so I need a few days of driving before I will know for sure if it has actually fixed my problem. I’ll post back here with an update if it didn’t fix my problem (if I don’t put an update, then problem fixed!)