Component Tests and General Diagnostics

Transmission Fluid Cooler





Special Tool(s)





Material

CAUTION: Whenever a transmission has been disassembled to install new parts or a new or remanufactured transmission has been installed, a new transmission fluid coolers (either in-tank, auxiliary or OTA) if equipped will need to be installed. Using a suitable torque converter/fluid cooler cleaner, clean and backflush the transmission fluid cooler tubes.

CAUTION: Use only clean automatic transmission fluid specified for this transmission. Do not use supplemental fluid additives, treatments or cleaning agent. The use of these materials may affect transmission operation and result in internal damage to the transmission

When internal wear or damage has occurred in the transmission, metal particles, clutch plate material or band material may have been carried into the transmission fluid cooler. These contaminants are a major cause of recurring transmission concerns and must be removed from the system before the transmission is put back in use.

When evidence of transmission fluid contamination (i.e., metal particles, clutch plate material or band material) is found in the cooling system, the transmission fluid cooler flow test should be carried out.

If the transmission cooling system fails the transmission fluid cooler flow test install a new transmission fluid cooler and flush out the fluid cooler lines. If installing a new transmission fluid cooler, use only factory approved components.

Transmission Fluid Cooler Flow Test

NOTE: The following components should be checked and should be within specification prior to carrying out this test:
^ Engine idle; refer to Computers and Control Systems.
^ Transmission fluid level; refer to Transmission Fluid Level Check Testing and Inspection
^ Line pressure; refer to Special Testing Procedures Special Testing Procedures
^ Transmission fluid must be at normal operating temperature, 66°C - 77°C (150°F - 170°F)

1. Place the transmission range selector lever into PARK.
2. Position the vehicle on a hoist.





3. Prior to carrying out this test, check to see if the vehicle is equipped with a transmission fluid in-line fluid filter. If the vehicle is equipped with a transmission fluid in-line fluid filter, it must be removed and discarded.





4. Using a 3/16 inch Allen key, hold the large drain plug with a wrench and remove the small (center) fluid level indicating plug.





5. Install the special tool into the pan.





6. Remove the cooler return line (upper line) from the fitting on the transmission case.
7. Connect one end of a clear hose to the cooler return line and route the other end of the hose to the special tool in the pan.
8. Lower the vehicle.
9. Start the engine and run it at idle.
10. With the engine running, place the vehicle in PARK and position the vehicle on a hoist.
11. Once a steady flow of fluid (without air bubbles) is observed, remove the hose from the special tool and place the hose in a measuring container for 15 seconds. After 15 seconds, place the hose back onto the special tool. Lower the vehicle and turn the engine off. Measure the amount of fluid in the container. If adequate flow is observed, approximately 208 ml (7 oz) will be in the measuring container. The test is now complete. Reconnect the cooler line and install the fluid fill plug.
12. If the flow is not adequate 208 ml (7 oz) in 15 seconds, disconnect the hose from the cooler return line and connect the hose to the cooler inlet (lower fitting) on the transmission case. Reconnect the cooler return line to the case (upper fitting) and continue with this procedure.
13. Repeat Steps 10-11 to see if the flow is now adequate.
^ If the flow is now approximately 208 ml (7 oz) in 15 seconds, install a new transmission fluid cooler and flush out the fluid cooler tubes. Test is complete.
^ If the flow is still not adequate 208 ml (7 oz) in 15 seconds the pump and/or torque converter may be at fault. Carry out the following procedures and checks:
- Carry out the torque converter diagnosis.
- Carry out the main control valve body procedure.
- Carry out the fluid pump procedure.
14. Once the procedure has been completed and adequate flow has been established, a new transmission in-line filter will need to be installed.