2015 Toyota Land Cruiser - Rough Shifting and VSC Lights

Exactly what @wqshaider said. That combination of lights is the car's way of telling you a major fault has been logged. Until you get the codes, it's just guessing, but common causes for this in the GCC region are: Faulty Wheel Speed Sensor: A damaged sensor or its wiring can confuse the ABS, VSC, and transmission systems. Throttle Body Issues: Carbon buildup or a failing throttle position sensor. Mass Air Flow (MAF) Sensor: If it's dirty or failing, it sends incorrect air intake data. But don't throw parts at it yet! Get the codes. It will save you time and money.

Thanks, @wqshaider and @qatmech. I borrowed a scanner from a neighbor. It's showing two codes: P0120 - Throttle/Pedal Position Sensor/Switch "A" Circuit Malfunction C1241 - Open in ABS Speed Sensor RL Circuit (or something similar for the rear left wheel) So it seems I have two problems at once? Could the throttle sensor code be causing the rough shifting and the ABS code the VSC lights?

@johncarguy, excellent! Now we have a clear path. You are correct in your thinking. The P0120 (Throttle Position Sensor) is very likely the cause of your rough shifting. The transmission control module uses throttle position data to decide how and when to shift. Bad data = bad, harsh shifts. The C1241 (Rear Left Wheel Speed Sensor) is the direct cause of the VSC/Trac lights, as those systems need data from all four wheels to function. I would focus on the P0120 first, as it's affecting drivability more critically.

Great diagnosis, @wqshaider. @johncarguy, for the P0120, don't immediately buy a new throttle body. It's often a wiring or connector issue. First, locate the throttle body on the engine. Disconnect the battery, then unplug the electrical connector to the throttle body. Inspect it very carefully for any loose, bent, or corroded pins. The dust and heat here can cause connection problems. Clean the connector with some electrical contact cleaner, plug it back in firmly, and see if the code returns after a drive.

Update: I followed your advice, @qatmech. I disconnected the battery and cleaned the throttle body connector. The pins looked okay. I reconnected everything, but the P0120 code came back after about 10 minutes of driving, and the rough shifting returned immediately. It seems the sensor itself might be faulty. The connector seemed fine.

That narrows it down perfectly, @johncarguy. Since the wiring and connector are good, the throttle position sensor (which is part of the throttle body assembly) is likely faulty. Replacement is the only fix. For the Land Cruiser, I strongly recommend an OEM part. Aftermarket ones can sometimes cause more issues. While you're in there, it's a good time to clean the throttle body bore with a throttle body cleaner and a soft cloth, but be careful not to damage the delicate throttle plate.

I agree with @wqshaider. Go OEM for the throttle body. As for the C1241 (wheel speed sensor), that's likely a separate, simpler fix. Once you have the P0120 sorted, get that one looked at. It could be a broken wire near the wheel (common from off-roading or just wear and tear) or a failed sensor. A mechanic can easily test it with a multimeter to confirm.