Toyota ECU Repair - Shift Issues

Toyota ECU Repair - Shift Issues Troubleshooting Guide

Important: Use this guide if you reinstalled your repaired Toyota ECU/ECM and the problem is still happening.

Important: Please do not open/disassemble the module. This can damage the unit and may void warranty coverage.

Step 1: Confirm the basics

• Fully charge the battery (low voltage can trigger shift/solenoid codes)
• Clear codes, then recheck after a short drive
  Step 2: Check transmission fluid (ATF)
• Verify ATF level is correct (check procedure varies by model)
• If fluid is burnt/dark or smells burnt, address fluid/service first
  Step 3: Check related fuses and power feeds
• Check EFI/ECM/IGN fuses (engine bay + interior)
• If any fuse is blown, find the cause before replacing again
  Step 4: Inspect transmission connectors and harness
• Key OFF
• Inspect the transmission external connector for:
• Fluid wicking into the connector
• Bent/pushed pins, corrosion, loose fit
• Harness rubbing/chafing near the trans, radiator, and battery tray
  Step 5: Verify solenoid circuit health (common cause of these codes)
• Have a shop measure solenoid resistance at the transmission connector
• If resistance is out of spec or open/shorted:
• Solenoid, internal trans harness, or valve body repair is typically needed
  Step 6: Check wiring continuity (if solenoids test OK)
• Verify continuity from ECU/ECM to transmission connector
• Check for shorts to ground/power on solenoid control wires
• Confirm engine/trans grounds are clean and tight
  Step 7: If P1760 returns specifically
• This often points to a pressure control / solenoid control circuit issue
• Common causes include valve body/solenoid faults, internal trans harness, or wiring problems
  Step 8: If symptoms continue with no codes
• Harsh shifts/slipping with no solenoid codes may be mechanical or valve body related
• A transmission specialist should confirm line pressure and valve body operation before replacing electronics
  If this guide doesn’t resolve the issue, contact UpFix for next-step help with your VIN, full code list, and what was found during the solenoid/wiring checks.