Powertrain Control Module (PCM) - 66RFE
P0733-GEAR RATIO ERROR IN 3RD
Special Tools:
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The transmission system uses two speed sensors, one to measure input rpm and one to measure output rpm. These inputs are essential for proper transmission operation. Therefore the integrity of this data is verified through the following checks:
NOTE: Various Gear Ratio Error DTCs will set only if the transmission slips after first achieving the correct ratio. Therefore, a transmission with no drive (or reverse) may not set any Gear Ratio Error DTC because it never achieves a correct gear ratio.
1) When in gear, if the gear ratio does not compare to a known gear ratio the corresponding in-gear DTCs P0729 and P0731-36 is set.
2) An excessive change in input or output speeds indicating an intermittent signal which results in DTCs P0716 and/or P0721 setting.
3) If the common speed sensor ground circuit is lost, both sensor inputs will read the signal from the input speed sensor at idle in neutral. Since the input speed sensor reads 60 teeth from the input clutch hub and the output speed sensor reads 30 teeth from the park gear, the result is an apparent speed ratio of 1:2 and may cause DTC P1794 to set when at a stop.
- When Monitored:
Continuously with the ignition on, engine running, and after the transmission achieves the correct gear ratio.
- Set Condition:
If the ratio of the Input rpm to the Output rpm does not match the current gear ratio then DTC P0733 will set. This DTC can take up to five minutes of problem identification before illuminating the MIL
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.
1. DETERMINING IF RELATED DTCs ARE PRESENT
1. With the scan tool, check for other transmission DTCs.
Are any Transmission solenoid, line pressure, speed sensor or loss of prime DTCs present?
Yes
- Perform the test for P0944-LOSS OF PRIME first if it is present. P0944.
No
- Go To 2
2. CHECK EVENT DATA
1. With the scan tool, read and record the Event Data.
NOTE: Make sure to record all Event Data stored in the scan tool for future reference in this test procedure.
Does the Event Data display information for DTC P0733?
Yes
- Go To 3
No
- Go To 6
3. CHECK RPM IN THE EVENT DATA
In the Event Data recorded earlier, does the Input rpm read zero?
Yes
- Check the input speed sensor and wiring. Refer to test P0716 and diagnose as if that DTC is current. P0716.
No
- Go To 4
4. CHECK LINE PRESSURE READING
In the Event Data recorded earlier, is the line pressure reading more than 10 psi below the desired line pressure?
Yes
- Go To 5
No
- Go To 6
5. PLUGGED TRANSMISSION OIL FILTER
1. Turn the ignition off to the lock position.
2. Remove and inspect the Transmission Oil Pan for excessive debris.
3. Remove and inspect the Primary Oil Filter.
NOTE: Make sure the Primary Transmission Oil Filter and/or seal is not cracked or split.
Does the Oil Pan contain excessive debris and/or is the Primary Oil Filter cracked or plugged?
Yes
- Repair the plugged, cracked, or split Primary Transmission Oil Filter and/or seal. If the Primary Transmission Oil Filter is plugged, refer to the Service Information for the proper hydraulic clutch repair procedure.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
No
- Remove the Transmission Oil Pump. Check the main Regulator Valve for sticking in its bore, scoring and/or damage and clean and repair as necessary. If no problem is found, replace the Transmission Solenoid/TRS Assembly.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
6. CHECK TO SEE IF DTC P0733 IS CURRENT
1. With the scan tool, perform the 3rd Gear Clutch Test. Follow the scan tool instructions.
2. Increase the throttle angle, TPS Degree to 30° for no more than a few seconds.
CAUTION: Do not overheat the transmission.
NOTE: If the 4C clutch is faulty, the overrunning clutch will hold and the slip test will pass. The 3rd Gear Clutch Test will not detect a faulty 4C clutch. However, it will detect a faulty UD clutch.
Did the clutch test pass, did the Input Speed remain at zero?
Yes
- Go To 7
No
- Go To 9
7. CHECK FOR INTERMITTENT OPERATION
1. Check the Shifter adjustment.
2. Intermittent gear ratio DTCs can set by problems in the Input and Output Speed Sensor circuits and/or Speed Sensor Ground circuit.
3. Check the Speed Sensor wiring and connectors for good connection then perform a wiggle test using the Transmission Simulator.
Were there any problems found?
Yes
- Repair as necessary.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
No
- Go To 8
8. CHECK FOR SLIPPAGE
1. With the scan tool, erase Transmission DTCs.
2. Road test the vehicle.
3. Check the Transmission is Reverse and all forward gears.
Is there an obvious slippage noted in any gear?
Yes
- Go To 11
No
- Go To 14
9. UD CLUTCH HYDRAULIC CIRCUIT
1. Remove Transmission Oil Pan and check for excessive debris.
2. Remove the Valve Body and air check the UD clutch hydraulic circuit (in the case).
NOTE: The UD clutch passage contains a small bleed orifice and a small amount of air leakage is normal.
Were there any problems found, excessive debris and/or excessive air leakage in the UD clutch hydraulic circuit?
Yes
- Repair as necessary. Check the UD clutch piston seals and the dribbler assembly, reaction shaft support seal rings and the flatness of the pump valve body and pump housing faces. Check main regulator valve for sticking in the bore.
NOTE: If the UD clutch has failed but no obvious cause is found (such as a cut piston seal, broken seal ring, stuck regulator valve, etc.) replace the Transmission Solenoid/TRS Assembly in addition to any necessary internal repairs.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test.
No
- Go To 10
10. UD ACCUMULATOR PISTON
1. Check the UD bleed orifice, accumulator piston and accumulator piston seal in the main valve body.
Were any problems found?
Yes
- Repair as necessary. Refer to the proper repair procedures.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
No
- Go To 11
11. EXCESSIVE DEBRIS
1. Remove the Transmission Oil Pan and check for excessive debris.
2. Remove the valve body and air check the 4C clutch hydraulic circuit.
NOTE: The 4C clutch passage contains a small bleed orifice and a small amount of air leakage is normal.
Were any problems found, excessive debris, improperly assembled 4C clutch and/or excessive air leakage in the 4C clutch hydraulic circuit?
Yes
- Repair as necessary. Refer to the proper repair procedures. Note: Check the 4C piston seals and bleed orifice.
NOTE: If the 4C clutch has failed but no obvious cause is found (such as a cut piston seal, broken seal ring, low line pressure in Event Data, etc.) replace the Transmission Solenoid/TRS Assembly in addition to any necessary internal repairs.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
No
- Go To 12
12. 4C ACCUMULATOR
1. Check the 4C Accumulator piston for cracks or a cut seal.
2. Check for a cut or missing No. 5 check ball.
3. Check the Solenoid Switch Valve and Plugs for sticking in its bore or excessive wear.
Were any problems found?
Yes
- Repair as necessary. Refer to the proper repair procedures.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
No
- Go To 13
13. CHECK FOR BROKEN REVERSE SUN GEAR WELD
Working through the windows in the bottom of the case, check the failed Reverse or reaction gear set connections follows:
1. Hold the Transmission Output Shaft by holding the Transmission Manual Lever in the park position.
2. Apply the 4C clutch using 30-40 psi shop air at the apply port in the center bulkhead.
3. Attempt to rotate the input annulus gear and drive shell (the drum that encloses the to rearmost gearsets). Note that (due to the overrunning clutch) the gear and drive shell normally rotates in one direction only.
Can the drive shell be rotated?
Yes
- Repair Transmission as necessary. Check the reverse annulus gear spline to the input carrier the reverse sun gear spline to the reaction carrier hub, and the reaction sun gear weld to the 4C clutch hub.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
No
- Go To 17
14. CHECK IF DTC RESET
Did DTC P0733 reset during the road test?
Yes
- Go To 15
No
- Go To 16
15. LIST OF POSSIBLE CAUSES
1. If any other DTCs set during the road test, perform to the appropriate diagnostics.
2. If no other DTCs set during the road test, below is a list of possible causes but not strictly limited to those:
3. Check for excessive debris in the Transmission Oil pan, plugged, cracked or split Primary Transmission Oil Filter and/or seal.
4. Check for cuts or missing No. 5 check ball in the main valve body.
5. Check the 4C and UD accumulator pistons and seals, UD bleed orifice and the Solenoid Switch Valve and Plugs in the main valve body.
6. Check the UD clutch piston seals, reaction shaft support seal rings and the flatness of the pump valve body and pump housing faces.
7. Check the 4C clutch piston seals and bleed orifice.
8. Check the UD clutch piston seals, reaction shaft support seal rings, dribbler assemblies and the flatness of the pump valve body and pump housing faces.
Repair
- Repair as necessary. Refer to the proper repair procedures.
NOTE: If the UD or 4C clutch has failed but no obvious cause is found (such as a cut piston seal, broken seal ring, stuck regulator valve or other items listed above) replace the Transmission Solenoid/TRS Assembly in addition to any necessary internal repairs.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
16. INTERMITTENT DTC
1. The conditions necessary to set this DTC are not present at this time.
2. Use the Event Data to help identify the conditions and/or possible causes that may have caused the DTC to set.
3. Check Service Information Tune-ups or Technical Service Bulletins that may apply.
Where any problems found?
Yes
- Repair as necessary.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
No
- Test Complete.
17. INTERMITTENT DTC
1. The conditions to set this DTC are not currently present.
2. With the scan tool, check the Event Data to help identify the conditions in which the DTC set.
- If the Event Data shows DTC P0733 was set in Park, Reverse or Neutral, replace the Powertrain Control Module.
- If the Event Data shows DTC P0733 set with input rpm = zero, check the input speed sensor and related wiring.
- If the Event Data shows DTC P0733 set with line pressure significantly below desired line pressure, check for the cause of low line pressure (i.e. oil level, misinstalled or damaged primary filter or filter seal, sticking main regulator valve in pump, etc.).
- If the Event Data shows DTC P0733 set with the UD or 4C pressure switch open (but line pressure matches Desired Line Pressure), air check the UD and 4C hydraulic clutch circuits for leakage. If the UD and 4C hydraulic clutch circuits are OK, replace the Transmission Solenoid/TRS assembly.
3. Check the gearshift linkage adjustment.
4. Intermittent Gear Ratio DTCs can be set by problems in the Input and Output Speed Sensor circuits and/or Speed Sensor Ground circuit.
5. Remove the Ignition Switch Feed fuse from the TIPM.
CAUTION: Removal of the Ignition Switch Feed fuse from the TIPM will prevent the vehicle from being started in gear.
WARNING: The Ignition Switch Feed fuse must be removed from the TIPM. Failure to do so can result in possible serious or fatal injury.
6. Install Transmission Simulator.
7. Wiggle wiring and connectors while checking for intermittent operation with the Transmission Simulator.
8. Gear ratio DTCs can also be set under extreme temperature conditions.
9. Verify if the problem is only experienced under extreme hot or cold conditions.
Were any problems found.
Yes
- Repair as necessary.
- Perform the 66RFE TRANSMISSION VERIFICATION TEST. 66RFE Transmission Verification Test
No
- Test Complete.