How to fix transmission slipping Toyota Corolla

Transmission slipping in a Toyota Corolla E170 (2013-2019) can manifest as delayed acceleration, engine revving without corresponding speed increase, or abrupt gear changes. Below is a detailed guide to diagnose and fix this issue.

Tools Required

• OBD-II Scanner
• Transmission Fluid Dipstick
• Clean Rags
• Jack and Jack Stands (if necessary)

Step 1: Check for Error Codes

1. Connect an OBD-II scanner to the diagnostic port beneath the dashboard.
2. Retrieve any stored codes related to transmission issues (e.g., P0700, P0730, etc.).
3. Note down these codes for further investigation.

Step 2: Inspect Transmission Fluid

1. Locate the Dipstick: With the engine running and the vehicle in park, locate the transmission fluid dipstick.
2. Check Fluid Level: Pull out the dipstick, wipe it clean, then reinsert and pull it out again to check the fluid level.
   • Low Fluid: Can cause slipping. If low, add the recommended type of transmission fluid (Toyota ATF WS).
   • Fluid Condition: Fluid should be bright red and not smell burnt. If dark or burnt, a fluid change is recommended.

Step 3: Examine for Leaks

1. Visual Inspection: Check under the vehicle and around the transmission for any signs of fluid leakage.
2. Inspect Seals and Gaskets: Look at common leak points like the transmission pan, axle seals, and cooler lines.

Step 4: Test Drive

1. Conduct a test drive to confirm the symptoms and note specific conditions under which slipping occurs (e.g., during acceleration, uphill, etc.).

Repair Instructions

Step 1: Transmission Fluid Replacement

1. Warm Up the Vehicle: Drive the car to warm up the transmission fluid.
2. Raise the Vehicle: Use a jack and jack stands to safely elevate the vehicle.
3. Drain Old Fluid: Place a drain pan under the transmission pan, remove the drain plug, and let the fluid drain completely.
4. Replace Transmission Filter: If applicable, remove the transmission pan, replace the filter, and reinstall the pan with a new gasket.
5. Refill Transmission Fluid: Add new fluid through the dipstick tube, matching the old fluid quantity or as specified in the owner’s manual.
6. Check Level: Start the engine, let it reach operating temperature, then check and adjust the fluid level as needed.

Step 2: Address Leaks

1. Seal Replacement: If leaks are identified, replace faulty seals or gaskets.
2. Tighten Connections: Ensure all connections and bolts are tightened to correct specifications.

Step 3: Reprogram or Replace Transmission Control Module (TCM)

1. If diagnostic codes indicate TCM issues, consider reprogramming or replacing the TCM following manufacturer guidelines.

Final Check

1. Re-check Fluid Levels: After a few days of driving, recheck fluid levels to ensure they remain stable.
2. Monitor Performance: Continue to monitor the vehicle’s performance for any further signs of slipping or issues.

If slipping persists after following these steps, further inspection by a professional may be necessary, as internal transmission components such as clutches or bands may be worn and require rebuilding or replacement.