Toyota Aqua problem

Lynlee from Sockburn

Help - can anyone troubleshoot this issue which my daughter ( in Auckland) is having with her Toyota Aqua? Ideas gratefully received! Here's her description below.

Car Details
Toyota Aqua 2014 110kms

Issue
- An unpredictable and sudden jamming of the brakes/wheels (unsure exactly) occurs when driving at speeds of between 60-80kmh around corners.
- It never happens driving uphill or on the flat, only while driving downhill.
- It doesn't occur when I am braking, only when my foot is sitting softly on the accelerator or when I am not accelerating at all.
- I feel a rattling under the accelerator (like a feeling of gravel rattling) and the traction control light flickers on and off intermittently. I also hear a slight electrical noise.

Further Detail
- The road conditions have never been wet or slippery when this issue occurs, and the road surface has always been even tarmac. I've also been driving within the recommended speed limit for the corners.
- The car drives with no issue around the city (speeds below 50kmh). The issue only occurs when driving on the open road out of town (higher speeds).
- Passengers notice the jamming, as it jolts the car when it happens.

Mechanic
- I took the car to Pitstop, as I originally attributed the issue to driving on a shingle road and possibly getting a little stone stuck underneath somewhere.
- They carried out a diagnostic scan which reported that everything was normal (no damage) and no stone / gravel stuck anywhere.

Summary
- The issue occurs infrequently, so is very unpredictable. This makes it difficult for a mechanic to just take it for a drive to experience the issue and assess whats wrong.

Possible issues
- Electrical issue or fault
- Traction control
- ABS
- Suspension
- Faulty wheel-speed sensors
- Tyres - size and condition
motoringmessageboard.com...