Initial Inspection and Diagnostic Overview

Inspection and Verification

CAUTION: When internal wear/damage occurs in the transmission, metal particles, clutch plate material and band material can travel into the torque converter, the transmission fluid cooler tubes, the in-tank transmission fluid cooler and the oil-to-air (OTA) auxiliary transmission fluid cooler, if so equipped. These contaminants are a major cause of recurring transmission concerns. To prevent future concerns, remove these contaminants from the cooling system before placing the transmission back into use. Refer to Automatic Transaxle/Transmission - 4R70E/4R75E or Automatic Transaxle/Transmission - TorqShift for transmission fluid cooler flow testing, backflushing and cleaning, torque converter cleaning and inspection, and flushing.

1. Visually inspect for obvious signs of mechanical damage, incorrect component installation and system leaks. Repair as necessary.
^ Install a new or remanufactured radiator when transmission fluid is found leaking from the in-tank transmission fluid cooler. Refer to Cooling System.
^ Install a new O-ring seal when transmission fluid is found leaking between the radiator transmission fluid cooler and the transmission fluid cooler fitting (not the cooler tube into the fitting). Refer to Component Test. Component Tests and General Diagnostics
^ Install a new oil-to-air (OTA) auxiliary transmission fluid cooler if there is leakage from the auxiliary transmission fluid cooler, and always as part of a transmission overhaul or exchange. Refer to Auxiliary Transmission Fluid Cooler.
2. If the fault is not visually evident, GO to Symptom Chart. Symptom Related Diagnostic Procedures