Shift flares and reverse issues
Scion tC and xB models that use a 4-speed automatic transmission, designated as U241E, can suffer from several different issues. In most cases, there will be severe slips or flares, with gear shifts between 2nd and 3rd gear being most noticeable.
This can also be accompanied by delays and failures when engaging in reverse or TCC lockup issues. None of these problems will trigger a check engine light.
- Excessive bore wear inside the solenoid modulator valve, which happens due to continuous movements of the valve itself and resulting side-load on the bore. This causes transmission fluid pressure spikes and leads to various shift issues. There are aftermarket kits with upgraded valve and sleeve assembly that allow the bore to be refurbished.
- Leaking O-rings at various end plugs, which causes leaks inside corresponding circuits. The resulting pressure losses will impact the control of various components and cause shift issues. Renewing end plugs eliminates leaks and restores proper function.
Grinding noise or vibrations while driving
Scions that use a 6-speed automatic transmission, being either a U760E inside a second-generation Scion tC or an A960E found in Scion FR-S, can develop a noticeable grinding noise coming from the engine bay while driving. This can sometimes be accompanied by a mild vibration.
Frequencies of both noise and vibration will become higher as the vehicle speeds up. In the initial phases, this will happen only when the vehicle is cold, but with time can become a constant issue.
- Worn or damaged rear cover bearing, which happens as a result of high mileage or poor maintenance. Situations like transmission fluid low level or skipped fluid changes will cause overheating, which results in bearing damage or excessive wear. Replacing the bearing is the only solution.
Harsh 2-3 shifts
Scion FR-S model that uses a 6-speed automatic transmission, designated as A960E, can have issues that affect 2-3 gear shifts.
This will either be a delayed and harsh upshift on accelerations or a harsh downshift from 3th to 2nd gear while coasting. In some cases, there will be a surge in engine speed. If severe enough, this may trigger a check engine light.
- Excessive wear inside the lockup control valve, which obstructs its movement and causes the Torque Converter Clutch to remain applied during gear changes, resulting in harsh shifts. If there is a leak and resulting pressure loss, this will prevent TCC lockup and cause surges and fluctuations of engine speed. Installing an upgraded and oversized lockup control valve kit restores controlled operation.
Scion FR-S model that uses a 6-speed automatic transmission, designated as A960E, can have various issues that range from shift flares to incorrect or harsh shift flares. Unlike TCC related issues, this can affect all gears and can even lead to burnt clutches if driving like that for a longer period of time.
- Excessive brake control valve bore and bodywear, which causes pressure losses or cross leaks to adjacent hydraulic circuits and upsets the delicate movement of the brake control valve. Refurbishing the bore and installing an oversized brake control valve kit will solve the issue.
Whining and rattling on acceleration
Several Scion models have a Continuously Variable Transmission version, which has several different designations, with all of them sharing the same issues. The most common one is a loud and severe whining noise while driving, which can be sometimes accompanied by a loud acceleration. There will be no other symptoms.
- Failed primary or secondary pulley bearing, which is a well-known issue that affects these transmissions and causes rattle and whining noise. Deciding on whether the primary or secondary bearing is the issue involves a test drive. If the tone and pitch of the noise change during downshifts, the fault is with the primary pulley bearing. If there is constant during shifts, the secondary pulley bearing is a probable fault. There are aftermarket upgraded bearings available on the market.