Automatic transmission diagnostics and testing

Diagnostic strategy

Troubleshooting an automatic transmission in an electronically controlled transaxle is simplified by using proven diagnostic techniques. One of the most important points is to remember that there are specific procedures that must be followed.

NOTE: Do not use so-called shortcuts or rely on the fact that crucial checks and adjustments have already been made.

Follow the procedures in the order they are presented. This will ensure that you do not miss any important diagnostic steps.

To properly diagnose the problem, the following publications are suggested:

• Engine Management/Emission Control (PCED) System Diagnostic Guide.
• TSB and OASIS messages.
• Electrical connection diagrams.

These publications provide information needed to diagnose problems in the transaxle. Use the diagnostic flow chart as a guide and follow the prescribed sequence of actions.

Preliminary inspection

• Knowing and understanding the client's problem.
• Verifying the validity of a customer complaint by performing a test drive/using the problematic vehicle system
• Checking the level and condition of the working fluid
• Check for non-factory installed accessories
• Checking the correct adjustment of the switching mechanisms
• Review TSB bulletins and OASIS messages relevant to the issue under consideration

Diagnostics

• Perform the ignition on-board diagnostic (KOEO) and ignition on-board diagnostic (KOER) procedures.
• Record all diagnostic trouble codes (DTCs).
• First, work on codes that are not related to the transmission.
• Then practice the codes related to the gearbox.
• Clear all permanent codes and try to reproduce them.
• Practice actions on permanent codes.
• If you receive only pass codes, go to the Symptom Diagnostic Index for additional information and diagnostic instructions.

Follow the diagnostic sequence to diagnose and fix the problem the first time.

Diagnostic flow chart

Examination	Result	Actions
Knowing and understanding the client's problem
Checking the level and condition of the working fluid
Verifying the validity of a customer complaint by performing a test drive/using the problematic vehicle system
Check for any non-factory installed accessories and verify proper installation
Checking the adjustment of the gear shift lever mechanism
Check technical service bulletins and OASIS messages for vehicle problem descriptions
Perform a quick check of both KOER and KOEO
Write down all the codes
1) Did you record any diagnostic trouble codes?	Yes	Perform the necessary actions for all serious diagnostic trouble codes. Perform pinpoint tests. Refer first to the PCED, then to the workshop manual.
	No	For more information, refer to Symptom Diagnosis in this section, then GO to step 5.
2) Are there any permanent codes in memory?	Yes	Clear codes and perform a drive cycle test.
	No	GO to step 4.
3) Are the permanent codes reappearing?	Yes	Practice the necessary actions for all permanent codes. Perform pinpoint tests. Refer to the PCED, then the Transaxle Manual, then the Shop Manual, then GO to step 4
	No	GO to step 4.
4) Is the problem resolved?	Yes	Perform a final quick check to ensure there are no diagnostic trouble codes. Clear the codes from memory. Return the vehicle to the customer.
	No	For more information, refer to Troubleshooting the Symptom in this section.
5) Are there any electrical problems?	Yes	Install a scan tool and perform an Output Condition Control test, then GO to step 6.
	No	Refer to the hydraulic and mechanical programs to diagnose and correct the problem, then GO to step 7.
6) Was the transaxle problem fixed after installing the scan tool?	Yes	Refer to the PCED Intermittent Failure Diagnostics section and use a scan tool to diagnose the cause of the problem in the processor, vehicle wiring harness, or external input devices (sensors or switches).
	No	Refer to the hydraulic and mechanical programs to diagnose and correct the problem, then GO to step 7.
7) Is the problem resolved?	Yes	Perform a final quick check to ensure there are no diagnostic trouble codes. Clear the codes from memory. Return the vehicle to the customer.
	No	Get help via the Technical Support Hotline.

Preliminary inspection

Before starting diagnostic procedures, the following points should be checked:

Knowledge and understanding of the problem

To properly diagnose a problem, first understand the customer complaint or problem condition. Direct contact with the customer may be necessary to begin to validate the customer complaint. Identify the conditions under which the problem occurs, such as:

• hot or cold vehicle units,
• high or low outside temperature,
• vehicle driving conditions,
• loaded or unloaded vehicle.

Once you have understood when and how the problem manifests itself, move on to checking the validity of the complaint.

Checking the status

This section provides information that should be used both in determining the actual cause of a customer complaint and in performing the appropriate procedures. The following procedures should be used when verifying the validity of a customer complaint about an engine.

Defining the client's problem

NOTE: Certain transaxle conditions may cause engine problems. Failure of the torque converter clutch to engage will cause the engine to stall.

Identify the customer's vehicle-related problems that are dependent on driving conditions, paying attention to the following points:

• high or low operating temperature of the vehicle,
• high or low outside temperature,
• character of the terrain,
• loaded or unloaded vehicle,
• driving in the city or on the highway,
• shifting to a higher gear (up),
• switching to a lower gear (down),
• inertial motion,
• engagement,
• noise/vibration - check for dependence on either crankshaft speed, or vehicle speed, or gear shifting, or selected gear, or selected range, or temperature.

Checking the fluid level

Under normal conditions, there is no requirement to check the transaxle fluid level. However, if the transaxle is not operating properly, is slipping, shifting is slow, or there is any sign of fluid leakage, the fluid level should be checked.

CAUTION: Do not operate the vehicle if the transmission fluid level is below the lower line on the dipstick and the outside temperature is above 10°C (50°F).

NOTE: Transmission fluid expands when heated. To accurately check the fluid level, drive the vehicle until normal operating temperature is reached, approximately 30 km (20 miles).

NOTE: If the vehicle has been driven for an extended period at high speeds, in city traffic in hot weather, or towing a trailer, the vehicle should be turned off for approximately 30 minutes to allow the fluid to cool before checking.

NOTE: An incorrect level of transmission fluid may affect the operation of the transmission in the drive axle unit and as a result may cause damage to the transmission in the drive axle unit. To properly check the transmission fluid level in the drive axle unit and top it up, refer to the procedures described in this section.

1. Drive the vehicle for 30 km (20 miles) or until the vehicle reaches normal operating temperature.

2. Park the vehicle on a level, horizontal surface and apply the parking brake.

3. Place your foot on the brake pedal, start the engine and move the range selector lever through all gear ranges. Allow sufficient time for each gear to engage.

4. Set the range selector to the "P" (park) position and leave the engine running.

5. Remove the transmission fluid dipstick and wipe it with a clean, lint-free cloth.

6. Install the fluid level dipstick, making sure it is firmly seated in the filler tube.


7. Remove the fluid level dipstick. The fluid level should be within the designated area.

Position	Name
1	Maximum liquid level
2	Normal operating temperature for checking fluid level is 66°C-77°C (150°F-170°F)
3	Minimum liquid level

High liquid level

Too high a fluid level can cause the fluid to become saturated with air. This occurs due to the agitation action of the rotating internal parts. This leads to chaotic fluctuations in the control pressure, foaming, fluid leakage from the ventilation pipe and can cause damage to the transmission in the block with the driving axle. If overfilling occurs, correct the fluid level.

Low fluid level

A low fluid level as a result can lead to poor engagement in the gearbox in the drive axle unit, slipping or damage. This may also indicate that there are leaks through one of the gearbox seals or gaskets in the drive axle unit.

Topping up transmission fluid

WARNING: The use of any other type of transmission fluid in the drive axle unit other than the prescribed one may cause damage to the transmission in the drive axle unit.

If transmission fluid needs topping up, add 0.25 L (1/2 pint) at a time through the filler tube. Do not overfill. Refer to the General Specifications table in this section for transmission fluid type information.

Checking the condition of the transmission fluid

1. Check the fluid level. For more information, refer to the "Checking the Fluid Level" section in this section.

2. Check the color and smell. The color under normal conditions should be reddish, but not brown or black.

3. Let the liquid drip onto a paper towel and examine the stain.

4. If solid particles are found, the transmission oil pan in the block with the drive axle should be removed for a more detailed inspection.

5. If transmission fluid contamination or transaxle damage is confirmed by sediment at the bottom of the oil pan, the transaxle should be disassembled and completely cleaned.

6. Perform diagnostic checks and adjustments. For more information, refer to Symptom-Based Diagnostics in this section.

Road test of the car

NOTE: Always drive safely, based on traffic conditions and following the Road Traffic Regulations.

The road test shift check and torque converter clutch operation check provide diagnostic information about the transaxle shift controls and torque converter operation.

Checking gear shift timing during road testing

This test confirms that the gear shift control system is operating correctly.

• 1. Bring the engine and transmission in the block with the drive axle to normal operating temperature.
• 2. Drive the vehicle with the gear selector lever in position "D" (overdrive switch engaged).
• 3. Open the throttle valve minimally and observe the speeds at which upshifts occur and the torque converter engages. Refer to the following Full Shift Ratio (FDR) Chart for the appropriate final drive ratios. (Also refer to the Automatic Transaxle Specifications brochure.)
• 4. Stop the vehicle. Select position "D" (overdrive switch off). Repeat step 3. The transaxle will perform all upshifts except the third to fourth gear shift, and torque converter clutch engagement should occur at speeds above 80 km/h (50 mph).
• 5. Press the accelerator pedal to the floor - the wide-open throttle (WOT) condition. The transmission in the block with the driving axle should switch from third to second gear, or from third to first, depending on the speed of the car. The torque converter clutch should also release.
• 6. At vehicle speeds above 48 km/h (30 mph), move the gear selector lever from position "D" to position "1" and release the accelerator pedal. The transaxle should immediately downshift to second gear. When vehicle speed drops below 32 km/h (20 mph), the transaxle should downshift to first gear.
• 7. If the transaxle fails to upshift/downshift or the torque converter clutch fails to engage/disengage. For more information, refer to Symptom-Based Diagnosis in this section - possible causes.

Table of speeds at which gear shifting occurs

Throttle position	Gear shifting	Final drive ratio 3.67:1		Final drive ratio 3.90:1		Final drive ratio 4.15:1
		km/h	mph	km/h	mph	km/h	mph
Closed	4-3	35-19	22-12	35-19	22-12	30-20	48-32
Closed	3-2	19-3	12-2	19-3	12-2	35-19	22-12
Closed	2-1	19-3	12-2	19-3	12-2	51-35	32-22
Minimum voltage of PID monitoring TP = 1.25 V	1-2	12-28	8-18	11-27	7-17	11-27	7-17
Minimum voltage of PID monitoring TP = 1.25 V	2-3	27-43	17-27	24-40	15-25	24-40	15-25
Minimum voltage of PID monitoring TP = 1.25 V	3-4	43-59	27-37	37-53	23-33	31-51	22-32
Wide open	1-2	41-57	26-36	45-61	28-38	43-59	27-37
Wide open	2-3	88-104	55-65	96-112	60-70	88-104	55-65
Wide open	3-4	123-140	77-87	135-151	84-94	138-154	86-96

Diagnostics of the torque converter

Before installing a new torque converter, all diagnostic procedures should be performed. This is necessary to avoid unjustified installation of new or remanufactured torque converters. Only after a complete diagnostic evaluation can a decision be made to install a new torque converter. Start with the usual diagnostic procedures, such as:

1. Preliminary inspection

2. Knowledge and understanding of the client's problem

3. Check the validity of the complaint - perform a torque converter clutch operation test; refer to the "Checking the Torque Converter Operation" section in this section.

4. Perform diagnostic procedures.

• Perform on-board diagnostics, refer to the chapter "On-board diagnostics using diagnostic equipment" in this section.
• Perform a line pressure test; refer to the "Checking Line Pressure" section in this section.
• Perform an engine speed limit check; refer to the "Checking the Engine Speed Limit" section in this section.
  • First, troubleshoot all DTC codes that are not related to the transmission in the drive axle unit.
  • Troubleshoot all DTC codes associated with the gearbox in the drive axle unit.
  • Perform on-board diagnostics to verify the repair performed.
• Perform symptom checklist diagnostics. For more information, refer to Symptom Checklist Diagnostics in this section.
  • Use the index to find the appropriate program that best describes the symptom(s) of the problem. The program will list all possible items that could be the cause of the problem or contribute to it. Check each item listed and perform the necessary diagnostics and repairs before replacing the torque converter.

Checking the operation of the torque converter

This test verifies that the torque converter clutch and torque converter control system are operating correctly.

1. Perform an on-line check, refer to "On-Board Diagnostics Using Diagnostic Equipment" in this section. Check for DTCs. Refer to the Diagnostic Trouble Code Table.

2. Connect a tachometer to the engine.

3. Bring the engine to normal operating temperature by driving the vehicle for approximately 15 minutes at highway speed with the transmission in the O/D position.

4. After reaching normal operating temperature, maintain a constant vehicle speed of approximately 80 km/h (50 mph) and lightly depress the brake pedal with your left foot.

5. When you lightly tap the brake pedal, the engine speed should increase, and then decrease five seconds after releasing the brake pedal. If this does not happen, refer to the section "Torque Converter Operation Problems" in the chapter "Diagnostics Based on the List of Malfunction Symptoms".

6. If the engine stalls in the O/D position or in the manual 2 position at idle with the vehicle stationary, move the selector lever to the manual 1 position. If the engine stalls, refer to "Torque Converter Operation Problems" in the "Symptom Diagnosis" section. Repair as necessary. If the engine does not stall in the O/D position. For more information, refer to Symptom Diagnosis in this section.

Visual inspection

This inspection identifies any changes or additions made to the vehicle systems that may affect diagnostics. Inspect the vehicle for any additional devices not installed at the Ford factory. These include:

Additional electronic elements:

• air conditioning system,
• generator,
• engine turbocharger,
• cell phone,
• cruise control,
• CB radio,
• linear amplifier,
• reversing alarm,
• computer.

Car modification:

These components, if installed incorrectly, will affect the operation of the powertrain control module (PCM) or transaxle. Pay particular attention to extra connections in the PCM or transaxle wiring harnesses, abnormal tire size, or changes in the transaxle gear ratio.

Leaks; refer to "Inspecting for Leaks" in this section.

Correct adjustment of the lever mechanism; refer to Section 307-05.

Checking the gear shift lever mechanism

Check the adjustment of the gear shift linkage by aligning the marks on the gearbox range selector lever with the marks on the gearbox. If the marks match, the fault is in the indicator. Do not adjust the gear shift linkage.

Hydraulic leakage in the mechanical control valve area can cause delayed engagement and slippage during operation if the linkage is not adjusted correctly; refer to Section 307-05 for shift linkage adjustment.

Checking TSB bulletins and OASIS messages

Refer to all technical service bulletins and OASIS messages that address transaxle problems and follow the prescribed procedure.

Perform on-board diagnostics (KOEO, KOER)

After road testing, with vehicle warmed up and before disconnecting any connectors, perform a quick scan check using a scan tool. Refer to PCED for powertrain management system diagnosis and testing.

Diagnostics

Special tool:

418-F224 Worldwide Diagnostic System (WDS) or equivalent scanner

Diagnosing an electronically controlled automatic transmission is made easier by using the following procedures. It is important to remember that there is a specific procedure that must be followed. Do not skip any steps or assume that important checks or adjustments have already been made. Perform the procedures in the order they are described. This will ensure that critical diagnostic steps are not missed. By following the diagnostic procedure sequence, the mechanic will be able to diagnose and fix the problem the first time.

On-board diagnostics using diagnostic equipment

NOTE: For detailed instructions and other diagnostic methods using the scanner, please contact the tester and PCED.

These operational tests should be used to diagnose the powertrain control module and should be performed in order.

• Operational check 1.0 - Visual inspection
• Operational Check 2.0 - Setup
• Operational check 3.0 - Ignition on, engine off
• Operational Check 4.0 - Permanent Memory
• Operational check 5.0 - Ignition on, engine running
• Special check mode
  • Deviation Check Mode
  • Output check mode
• PCM Reset Mode
• Clearing DTC
• OBD II Driving Cycle
• Other scanner resources

For more information on other diagnostic testing resources using the scanner, please refer to PCED. Other diagnostic methods include:

• Parameter Identification (PID) Access Mode
• Freeze Frame Data Access Mode"
• Oxygen sensor monitoring mode

Checking the gearbox movement cycle in the block with the driving axle

NOTE: Always drive safely, based on traffic conditions and obey traffic laws.

NOTE: The transaxle drive cycle test must be followed precisely. The transaxle failure must occur four times in a row to set a Shift Malfunction DTC, and five times in a row to set a Torque Converter Clutch Continuous Code.

NOTE: When performing the transaxle drive cycle check, refer to the solenoid activation table for proper solenoid operation.

After performing the operational test, use the transaxle drive cycle test to check for continuous codes.

1. Write down and then erase the operational verification codes.

2. Warm up the engine to normal operating temperature.

3. Make sure that the transmission fluid level in the transaxle is correct.

4. With the transaxle in the "O/D" position, accelerate at a moderate speed from a standstill to 80 km/h (50 mph). This will allow the transaxle to shift into fourth gear. Maintain a constant speed and a steady open throttle for at least 15 seconds.

NOTE: PCA, EPC and VFS are all solenoids. PCA is preferred for this transmission because PCA will show up on the scan tool display.

5. With the transaxle in fourth gear and the speed and throttle position stable, lightly depress and release the brake pedal to turn on the brake lights. Then keep the speed constant and the throttle position stable for at least 5 seconds.

6. Brake to a complete stop and leave the vehicle stationary for at least 20 seconds.

7. Repeat steps 4 at least 6 times.

8. Perform a quick check and record continuous DTCs.

After on-board diagnostics

NOTE: Vehicle wiring harnesses, powertrain control module, and sensors not related to the transaxle may affect transaxle operation. Correct these conditions first.

After performing all on-board diagnostic procedures, repair all DTCs. Start with non-transaxle related DTCs, then troubleshoot any transaxle related DTCs. Refer to the Diagnostic Trouble Code (DTC) chart for conditions and symptoms. This chart will be helpful in referring you to the correct manuals and in diagnosing internal transaxle faults and external non-transaxle related inputs. Pinpoint tests are used to diagnose electrical faults. Make sure to also diagnose the vehicle wiring harnesses and the PCM. The PCED will help diagnose non-transaxle related electronic components.

Before pinpoint tests

NOTE: Before entering pinpoint tests, inspect the powertrain control module wiring harnesses for proper connections, bent or broken pins, corrosion, loose wires, proper routing, proper sealing, and overall condition. Inspect the PCM, sensors, and actuators for damage.. Please contact PCED.

NOTE: If the fault is not corrected after diagnosing the electrical components, refer to Symptom-Based Diagnosis in this section for more information.

If DTCs are displayed while running OBD, refer to the Diagnostic Trouble Code (DTC) table for the appropriate repair procedure. Refer to any TSBs and OASIS messages for information on transaxle faults before entering pinpoint tests.