Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Fail-Safe Chart
- FAIL-SAFE
This function minimizes the loss of the ECT functions when any malfunction occurs in each sensor or solenoid.
- Vehicle speed signal (SPD):
When there are problems with vehicle speed signals, 4th upshift is prohibited.
- Input turbine speed sensor NT (Speed sensor NT):
When the input turbine speed sensor has a malfunction, 4th upshift is prohibited.
- ATF (Automatic Transmission Fluid) temperature sensor:
When the ATF temperature sensor has a malfunction, 4th upshift is prohibited.
- Shift solenoid valve SLU:
If the ECM detects a malfunction in the solenoid valve SLU, it turns the valve off.
- Shift solenoid valve SLT:
When the solenoid valve SLT has a malfunction, 4th upshift is prohibited.
- Engine coolant temperature sensor:
When the engine coolant temperature sensor has a malfunction, 4th upshift is prohibited.
- Knock sensor:
When the knock sensor has a malfunction, 4th upshift is prohibited.
- Throttle position sensor:
When the throttle position sensor has a malfunction, 4th upshift is prohibited.
- Shift solenoid valve S1 and S2:
Fail-safe function:
If either of the shift solenoid valve circuits develops an open or short, the ECM turns the other shift solenoid "ON" and "OFF" in order to shift into the gear positions shown in the table below.
The ECM also turns the shift solenoid valve ST OFF at the same time. If both solenoids malfunction, hydraulic control cannot be performed electronically and must be done manually.
Manual shifting as shown in the following table must be done (In case of a short circuit, the ECM stops sending current to the short circuit solenoid).
Even if starting the engine in the fail-safe mode, the gear position remains in the same position.
Position NORMAL SHIFT SOLENOID S1 MALFUNCTIONING Solenoid valve Gear Solenoid valve Gear S1 S2 S1 S2 D ON ON 1st X ON → OFF 3rd ON OFF 2nd X OFF 3rd OFF OFF 3rd X OFF 3rd OFF ON 4th X ON 4th 3 ON ON 1st X ON → OFF 3rd ON OFF 2nd X OFF 3rd OFF OFF 3rd X OFF 3rd 2 ON ON 1st X ON → OFF 3rd ON OFF 2nd X OFF 3rd L ON ON 1st X ON → OFF 3rd Position SHIFT SOLENOID S2 MALFUNCTIONING BOTH SOLENOIDS MALFUNCTIONING Solenoid valve Gear Gear when shift selector is manually operated S1 S2 D ON X 2nd 3rd ON X 2nd 3rd OFF X 3rd 3rd OFF X 3rd 3rd 3 ON X 2nd 3rd ON X 2nd 3rd OFF X 3rd 3rd 2 ON X 2nd 3rd ON X 2nd 3rd L ON X 2nd 3rd - X: OFF (the ECM stops sending current to a malfunctioning solenoid valve)
- →: Condition in the electrical malfunction is shown on the left of "→".
Condition in the fail-safe mode is shown on the right of "→".
- Vehicle speed signal (SPD):
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.