Automatic Transmission Slipping in 3rd Gear: Troubleshooting Guide

Toyota Prado 150 Series
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Introduction

This guide addresses the issue of an automatic transmission slipping specifically in 3rd gear. It covers potential causes and troubleshooting steps.

Problem

The automatic transmission occasionally slips when shifting into 3rd gear. The issue is intermittent, occurring a few times a day. The vehicle has approximately 145,000 km on the odometer.

Potential Causes

  • Software/Firmware Issue: A software update may be available for the transmission control unit (TCU) addressing this specific issue, especially for 6-speed transmissions. Consult a dealer to check for available updates.
  • Solenoid Malfunction: Intermittent slipping can be attributed to a faulty valve or solenoid within the transmission.
  • Mechanical Wear: Although less likely given the intermittent nature of the problem, worn clutch packs can cause slippage.

Solution

  1. Check for TCU Software Updates: Contact a dealer to inquire about software updates for the transmission control unit (TCU).
  2. Investigate Solenoids: If a software update doesn’t resolve the issue, further diagnostics are needed to test individual solenoids.

Notes

  • A recent transmission service (fluid and filter change) did not resolve the slipping issue.
  • The transmission fluid appeared to be in good condition during the service, with no excessive debris on the magnet.

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