P0733
P0733-GEAR RATIO ERROR IN 3RD
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:
1) Once in a particular gear, if the gear ratio varies from the correct gear ratio, the corresponding in-gear trouble code is set (DTCs P0731-36 and P1736).
2) An excessive change in input or output speeds indicating signal intermittent will result in the DTCs P0716 and/or P0721 being set.
3) If the common speed sensor ground circuit is lost, both sensor inputs will read the pulses from the input speed sensor when at a stop 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 the DTC P1794 to set.
- When Monitored:
Continuously with the ignition on, engine running, and after the transmission has achieved the proper gear ratio.
- Set Condition:
If the ratio of the Input rpm to the Output rpm does not match the current gear ratio. 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. CHECK IF RELATED DTCS ARE PRESENT
1. With the scan tool, check for other transmission DTCs
Are there any Transmission solenoid, line pressure, speed sensor, and/or loss of prime DTCs present?
Yes
- Perform the appropriate diagnostic procedure. 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 the DTC P0733?
Yes
- Go To 4
No
- Go To 3
3. CHECK THE TARGET GEAR IN Event Data
In the Event Data recorded earlier, does the Event Data display information for the DTC P1790, with target gear = 3rd, or with both OD and UD clutches applying?
Yes
- Go To 4
No
- Go To 7
4. CHECK INPUT RPM IN 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 the DTC is current. P0716
No
- Go To 5
5. 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 6
No
- Go To 7
6. CHECK 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 seal are properly installed and are not cracked or split.
Does the Oil Pan contain excessive debris and/or is the Primary Oil Filter cracked, plugged or mis-installed?
Yes
- Repair the plugged, cracked, or split Primary Transmission Oil Filter and/or seal. If excessive clutch debris is present, check the clutches for damage. Refer to the Service Information for the proper hydraulic clutch repair procedure.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE 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 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
7. CHECK IF THE DTC IS CURRENT
1. With the scan tool, perform the 3rd Gear Clutch Test. Follow the instructions on the scan tool.
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 OD clutch is faulty, the overrunning clutch will hold and the slip test will pass. The 3rd gear clutch test will not detect a faulty OD clutch. However, it will detect a faulty UD clutch.
Did the clutch test pass, did the Input Speed remain at zero?
Yes
- Go To 8
No
- Go To 10
8. CHECK FOR INTERMITTENT OPERATION
1. Check the Shifter adjustment.
2. Intermittent gear ratio DTCs can be set by problems in the Input and Output Speed Sensor circuits and/or Speed Sensor Ground circuit.
3. Remove the Starter Relay.
CAUTION: Removal of the Starter Relay will prevent the vehicle from being started in gear.
WARNING: The Starter Relay must be removed from the PDC. Failure to do so may result in possible serious or fatal injury.
NOTE: Failure to remove the Starter Relay can cause a Transmission - No Response condition.
4. Install the Transmission Simulator 8333A.
5. Check the Speed Sensor wiring and connectors for good connection, then perform a wiggle test using the Transmission Simulator 8333A.
Were there any problems found?
Yes
- Repair as necessary.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
No
- Go To 9
9. CHECK FOR SLIPPAGE
1. With the scan tool, erase Transmission DTCs.
2. Road test the vehicle. Check operation in 3rd gear, 4th gear, and Reverse.
Is there an obvious slippage noticed in 3rd gear, or runaway on the 2-3 shift?
Yes
- Go To 12
No
- Go To 16
10. CHECK THE UD HYDRAULIC CLUTCH CIRCUIT
1. Remove Transmission Oil Pan and check for excessive debris.
2. Remove the Valve Body and air check the UD hydraulic clutch circuit (in the case).
NOTE: The UD clutch passage contains a small bleed orifice, a small amount of air leakage is normal.
Were there any problems found, excessive debris and/or excessive air leakage in the UD hydraulic clutch circuit?
Yes
- Repair as necessary. Check the UD clutch piston seals, reaction shaft support seal rings and dribbler assemblies, 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 or any other items listed above) replace the Transmission Solenoid/TRS Assembly in addition to any necessary internal repairs.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
No
- Go To 11
11. CHECK UD ACCUMULATOR PISTON
1. Check the UD bleed orifice, accumulator piston, and accumulator piston seal in the main valve body.
Were there any problems found?
Yes
- Repair as necessary. Refer to the Service Information for proper repair procedures.
No
- Replace Transmission Solenoid/TRS Assembly. Transmission Solenoid and TRS Assembly - Removal.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
12. CHECK FOR EXCESSIVE DEBRIS
1. Remove the Transmission Oil Pan and check for excessive debris.
2. Remove the valve body and check if the accumulator cover is intact.
3. Air check the OD hydraulic clutch circuit (in the case).
NOTE: The OD clutch passage contains a small bleed orifice which connects to the Reverse clutch hydraulic circuit, a small amount of air leakage into the Reverse clutch passage is normal.
Were there any problems found, excessive debris, and/or excessive air leakage in the OD hydraulic clutch circuit?
Yes
- Repair as necessary. Refer to the Service Information for proper repair procedures. Note: Check the bleed orifice in the OD/Reverse clutch piston.
NOTE: If the OD clutch has failed but no obvious cause is found (such as a cut piston seal, broken seal ring, stuck regulator valve or any other items listed above) replace the Transmission Solenoid/TRS Assembly in addition to any necessary internal repairs.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
No
- Go To 13
13. CHECK THE OD ACCUMULATOR
1. Check the OD Accumulator piston for cracks or a cut seal.
2. Check for a cut or missing No. 6 check ball.
3. Check the Solenoid Switch Valve and its plugs for sticking in its bore or excessive wear.
Were there any problems found?
Yes
- Repair as necessary. Refer to the Service Information for proper repair procedures.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
No
- Go To 14
14. CHECK FOR NO REVERSE
During the road test on a previous test, did the vehicle have no reverse and no 3rd gear, but 1st and 2nd gears were OK?
Yes
- Go To 15
No
- Replace Transmission Solenoid/TRS Assembly. Transmission Solenoid and TRS Assembly - Removal.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
15. CHECK FOR BROKEN REVERSE CARRIER WELD
1. Remove the Transmission and inspect the weld on the reverse carrier hub.
Were there any problems found?
Yes
- Repair as necessary.
No
- Disassemble and inspect the input clutch assembly. Check the OD and Reverse clutch seals, discs, and bleed orifice (in the OD/Reverse clutch piston). Check the OD hub and shaft. Repair as necessary. Refer to the Service Information for proper repair procedures.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
16. CHECK IF DTC RESETS
Did the DTC P0733 reset during the road test?
Yes
- Go To 17
No
- Go To 18
17. LIST OF POSSIBLE CAUSES
1. If any other DTCs set during the road test, refer to the appropriate test in the Transmission category.
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 mis-installed Primary Transmission Oil Filter and/or seal.
- Cut or missing No. 6 check ball in the main valve body.
- OD and UD accumulator pistons and seals and bleed orifices, and the Solenoid Switch Valve and Plugs in the main valve body.
- OD and UD clutch piston seals, reaction shaft support seal rings and dribbler assemblies, and the flatness of the pump valve body and pump housing faces.
- Main regulator valve for sticking in its bore.
Repair
- Repair as necessary. Refer to the Service Information for proper repair procedures.
NOTE: If the OD or UD clutch has failed but no obvious cause is found (such as a cut piston seal, broken seal ring, stuck regulator valve or any other items listed above) replace the Transmission Solenoid/TRS Assembly in addition to any necessary internal repairs.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
18. CHECK FOR INTERMITTENT OPERATION
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 was set.
- If the Event Data shows fault P0733 was set in the Park, Reverse, or Neutral, replace the Powertrain Control Module.
- If the Event Data shows fault P0733 set with input rpm = zero, check the input speed sensor and related wiring.
- If the Event Data shows fault P0733 set with line pressure significantly below desired line pressure, check for the cause of low line pressure (i.e., oil level, mis installed or damaged primary filter or filter seal, sticking main regulator valve in pump, etc.).
- If the Event Data shows fault P0733 set with the OD or UD pressure switch open (but line pressure matches Desired Line Pressure), air check the OD and UD hydraulic clutch circuits for leakage. If the OD and UD 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 Starter Relay.
CAUTION: Removal of the Starter Relay will prevent the vehicle from being started in gear.
WARNING: The Starter Relay must be removed from the PDC. Failure to do so may result in possible serious or fatal injury.
NOTE: Failure to remove the Starter Relay can cause a Transmission - No Response condition.
6. Install the Transmission Simulator 8333A.
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 there any problems found.
Yes
- Repair as necessary.
- Perform the 545RFE TRANSMISSION VERIFICATION TEST. . 545RFE Transmission Verification Test
No
- Test Complete.