Automatic Transmission: Maintenance Ford Focus I facelift

Transmission Fluid Temperature (TFT) Sensor

The transmission fluid temperature (TFT) sensor is located on the internal wiring harness to the solenoid valves in the fluid pan.

It is a resistor and measures the transmission fluid temperature.

The transmission fluid temperature is used by the PCM for the following functions

1. Applying the torque converter clutch is not permitted until the transmission fluid reaches a certain temperature.
2. Engagement of 4th gear is prevented in extreme sub-zero temperatures until the normal operating temperature is reached.
3. If the transmission fluid temperature is excessive, a pre-set fixed shift curve is selected and the torque converter lock-up clutch is closed in 2, 3 and 4, and the transmission warning indicator is activated. No substitute signal is available for the TFT sensor.

Scheme 41

The O/D switch transmits a signal to the PCM to select or suppress 4th gear in manual selector lever position D.

The signal of the O/D switch is used for the following functions

1. as an input signal to convey the driver's intent to the PCM.
2. to display the driver's intent with the O/D indicator in the instrument cluster.

No substitute signal is available for the O/D switch. If it should fail, it is always possible to shift into 4th gear in manual selector lever position D.

Scheme 42

When the ignition is switched on, the manual selector lever shift lock solenoid is actuated by depressing the brake (signal from the stoplamp switch). This retracts the locking pin so that the manual selector lever can be moved out of position P.

Scheme 43

Note. If P is selected again, the manual selector lever is locked again.

If the brake signal should fail due to a malfunction, manual unlocking is possible.

For this, the cover of the release mechanism must be removed and a suitable object (ignition key) pressed into the opening until the manual selector lever can be moved out of position P.

Check Transmission Fluid Level

Under normal conditions, there is no requirement to check the transmission fluid level. However, if the transaxle is not functioning correctly, the transaxle may slip, shift slowly or there may be some sign of transmission fluid leakage, the transmission fluid level should be checked.

The vehicle should not be driven if the transmission fluid level is below the bottom line on the transmission fluid level indicator and the ambient temperature is above 10°C (50°F).

Note. Transmission fluid expands when warmed. To obtain an accurate transmission fluid level check, drive the vehicle until normal operating temperature is reached, approximately 30 km (20 mi).

Note. If the vehicle has been operated for an extended period at high speeds, in city traffic, during hot weather or while pulling a trailer the vehicle should be turned OFF for approximately 30 minutes to allow the transmission fluid to cool before checking.

Note. Incorrect transmission fluid level may affect the transaxle operation and could result in transaxle damage.

1. Drive the vehicle 30 km (20 mi) or until the vehicle reaches normal operating temperature.
2. Park the vehicle on a level surface and engage the parking brake.
3. With foot on the brake, start the engine and move the selector lever through all the gear ranges. Allow sufficient time for each gear to engage.
4. Place the selector lever in PARK and leave the engine running.
5. Remove the transmission fluid level indicator and wipe it clean with a lint free cloth.
6. Install the transmission fluid level indicator, making sure that it is fully seated in the filler tube.
7. Remove the transmission fluid level indicator. The transmission fluid should be within the designated areas.

Scheme 44

High Transmission Fluid Level

A transmission fluid level that is too high may cause the transmission fluid to become aerated due to the churning action of the rotating internal parts. This will cause erratic control pressure, foaming, loss of transmission fluid from the vent tube and possible transaxle damage. If an overfill reading is indicated, adjust the transmission fluid to correct level.

Low Transmission Fluid Level

A low transmission fluid level could result in poor transaxle engagement, slipping or damage. This could also indicate a leak in one of the transaxle seals or gaskets.

Adding Transmission Fluid

The use of any other type of transmission fluid than specified could result in transaxle damage.

If transmission fluid needs to be added, add transmission fluid in 0.25L (1/2 pt) increments through the transmission filler tube. Do not overfill the transmission fluid. For transmission fluid type, refer to SPECIFICATIONS .

Check The Transmission Fluid Condition

1. Check the transmission fluid level.
2. Observe the color and the odor. The color under normal circumstances should be reddish, not brown or black.
3. Allow the transmission fluid to drip onto a facial tissue and examine the stain.
4. If evidence of solid material is found, the transmission fluid pan should be removed for further inspection.
5. If fluid contamination or transaxle failure is confirmed by the sediment in the bottom of the transmission fluid pan, the transaxle must be disassembled and completely cleaned.
6. Carry out diagnostic checks and adjustments. Refer to «Diagnosis By Symptom»(ref-278257-S14289017952008012400000) .

Water in Transmission Fluid

To correctly repair an automatic transmission or transaxle that has had water or coolant introduced into the system, completely disassemble, clean and replace the following parts

1. All internal and external seals
2. All friction material; clutches and bands
3. Torque converter
4. All parts with bonded seals
5. All solenoids
6. All transmission fluid filters

Prior to installing the transmission or transaxle, the transmission fluid cooler(s), transmission fluid cooler tubes and transmission fluid cooler hoses need to be flushed and cleaned.

Transmission Fluid Cooler

Whenever the transaxle has been disassembled to install new parts, clean and backflush the transmission fluid cooler or contaminants in the transaxle cooling system can cause failure of the transaxle.

Note. Cleaning and backflushing the transmission fluid cooling system along with normal cleaning and inspection procedures as outlined in this article during disassembly and reassembly will keep contamination from reentering the transaxle and causing a repeat repair.

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

Transmission Fluid Cooler Backflushing and Cleaning

Material

MERCON®V, MERCON®SP, Motorcraft Premium Automatic Transmission Fluid and Motorcraft Continuously Variable Chain Type Transmission Fluid are not interchangeable transmission fluids. The use of any transmission fluid other than what is recommended for this transaxle will cause transaxle damage. Refer to Material table for the correct fluid.

Do not use water-based cleaners, mineral spirits, brake cleaner or solvents that may contain acetone, xylene or heptane to clean and/or flush the transaxle assembly, transaxle components or the torque converter, transaxle damage will occur. Use only clean transmission fluid designated for the transmission/converter being serviced.

1. Carry out backflushing with a suitable torque converter/transmission fluid cooler cleaner. Test equipment to make sure that a vigorous transmission fluid flow is present before proceeding. Install a new system filter if flow is weak or contaminated.
2. Remove the transmission fluid cooler tubes. For additional information, refer to «TRANSAXLE/TRANSMISSION COOLING»(ref-278310) article.
3. To aid in attaching the cleaner to the transmission fluid cooler, install rubber hoses on the metal inlet and outlet tubes on the transmission fluid cooler. Install the cleaner on the rubber hoses as follows: Connect the cleaner tank pressure tube to the transmission fluid cooler return tube. Connect a tank return hose to the transmission fluid cooler pressure tube. Place the outlet end of this hose in the transmission fluid tank reservoir.
4. Turn on the transmission fluid pump and allow the transmission fluid to circulate a minimum of 5 minutes (cycling switch on and off will help dislodge contaminants in cooling system).
5. Switch off the cleaner and disconnect the pressure hose from the transmission fluid cooler return tube.
6. Clean the transmission fluid cooler tubes by hand.
7. Use compressed air to blow out the cooler(s) and tubes (blow air into the transmission fluid cooler return tube) until all fluid is removed.
8. Remove the rubber hoses from the transmission fluid cooler and install the transmission fluid cooler tubes. For additional information, refer to «TRANSAXLE/TRANSMISSION COOLING»(ref-278310) article.
9. Check the transmission fluid level.

Transmission Fluid Drain and Refill

Material

1. With the vehicle in NEUTRAL, position it on a hoist. For additional information, refer to «JACKING AND LIFTING»(ref-278237) article.
2. Disconnect the return hose from the transmission fluid cooler. Push the connector fitting into the cooler line. Press the yellow release button. Pull the connector fitting off the cooler line.
3. Attach a length of suitable drain hose to the transmission fluid cooler return tube.
4. Lower the vehicle.
5. Insert the drain hose into a calibrated 10 liter (10.5 quarts) container.
6. Run the engine at idle and pump out 3L (3.17 qt) of automatic transmission fluid.
7. Switch OFF the engine.
8. Remove the fluid level indicator from the fluid level indicator tube.
9. Add 3 liters of automatic transmission fluid to the transaxle.
10. Run the engine at idle and pump out 3L (3.17 qt) of automatic transmission fluid.
11. Switch OFF the engine.
12. Add 3L (3.17 qt) of automatic transmission fluid to the transaxle.
13. Run the engine at idle and pump out 3L (3.17 qt) of automatic transmission fluid.
14. Switch OFF the engine.
15. Raise the vehicle.
16. Remove the length of suitable drain hose from the transmission fluid return hose.
17. Connect the return hose to the transmission fluid cooler.
18. Lower the vehicle.
19. Add 3L (3.17 qt) of automatic transmission fluid to the transaxle.
20. Install the fluid level indicator to the fluid level indicator tube.
21. Run the engine.
22. Check the automatic transmission fluid level and fill if necessary.

Transmission Fluid Pan

Material

Scheme 45