The transmission control module (TCM) calculates gear ratio based on data from the automatic transmission input shaft speed (AT ISS) and automatic transmission output shaft speed (AT OSS) sensors. The TCM compares the calculated gear ratio to the known gear ratio for each commanded gear.
If the TCM detects an incorrect 3rd gear ratio, indicating excessive slip or drag within the transmission, then DTC P0733 sets. DTC P0733 is a type A DTC.
This diagnostic procedure supports the following DTC:
DTC P0733 Incorrect 3rd Gear Ratio
• | No TR switch DTC P0705. |
• | No transmission fluid temperature (TFT) DTCs P0711, P0712, or P0713. |
• | No ISS DTC P0717. |
• | No OSS DTC P0722. |
• | No engine speed DTC P0727. |
• | No torque converter clutch (TCC) DTC P0741. |
• | No solenoid DTCs P0962, P0963, P0966, P0967, P0970, P0971, P0973, P0974, P0976, P0977, P0979, P0980, P0982, P0983, P0985, or P0986. |
• | No engine torque DTC P1781. |
• | No throttle position DTC P1791. |
• | No controller area network (CAN) DTCs U2104 or U0100. |
• | The brake switch is released. |
• | The ignition voltage is 10.5-18 volts. |
• | The transmission temperature is greater than 20°C (68°F). |
• | The transmission is in a forward range. |
• | The elapsed time since the most recent range change is 8 seconds or greater. |
• | The throttle position (TP) is 10 percent or greater. |
• | The engine speed is at least 400 RPM. |
• | The commanded gear has been 3rd for 0.5 seconds or greater. |
• | The transmission output shaft speed (OSS) is 500 RPM or greater. |
The TCM commands 3rd gear and the actual gear ratio is not within 1.54:1-2.31:1 for 12 seconds.
• | The TCM requests the powertrain control module (PCM) to illuminate the malfunction indicator lamp (MIL). |
• | The TCM turns the Trans. Protection Mode ON. |
• | The transmission will operate in 5th gear when the transmission is shifted into D range and 2nd gear when shifted into L range. |
• | The line pressure is at maximum. |
• | The TCC is disabled. |
• | The TCM freezes the transmission adaptive functions. |
• | The TCM requests the PCM to limit engine torque to 150 N·m (111 lb ft). |
• | The PCM records the operating conditions when the Condition for Setting the DTC are met. The PCM stores this information as Freeze Frame and Failure Records. |
• | The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as a Failure Record. |
• | The TCM stores DTC P0733 in TCM history. |
• | The PCM turns off the MIL after the third consecutive drive trip in which the TCM does not send a MIL illumination request. |
• | A scan tool can clear the DTC. |
• | The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without an emission-related diagnostic fault occurring. |
• | The TCM cancels the DTC default actions when the ignition is OFF long enough in order to power down the TCM. |
Ask the customer about overloading the vehicle, or exceeding the trailer towing limit.
The numbers below refer to the step numbers on the diagnostic table.
This step determines that shift solenoid 2 or the M2 shift valve is stuck if the 3rd gear ratio is 1.45:1.
This step determines that shift solenoid 4 or the U1 shift valve is stuck if the 3rd gear ratio is 2.89:1.
This step determines if the output shaft speed sensor signal is skewed by a large factor.
This step determines if the input shaft speed sensor signal is skewed by a large factor.
Step | Action | Values | Yes | No | ||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |||||||||||||
2 | Perform the Transmission Fluid Checking Procedure. Refer to Transmission Fluid Check . Is the transmission fluid level correct? | -- | Go to Step 4 | Go to Step 3 | ||||||||||||
3 |
Did you find and correct the condition? | -- | Go to Step 27 | Go to Step 4 | ||||||||||||
4 |
Important:
Is the 3rd gear ratio within the specified range? | 1.54:1-2.31:1 | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 5 | ||||||||||||
Is the 3rd gear ratio equal to the specified value? | 1.45:1 | Go to Step 14 | Go to Step 6 | |||||||||||||
Is the 3rd gear ratio equal to the specified value? | 2.94:1 | Go to Step 15 | Go to Step 7 | |||||||||||||
Is Transmission OSS parameter reading correctly? | -- | Go to Step 8 | Go to Step 20 | |||||||||||||
Is Transmission AT ISS parameter within the specified range? | 400-800 RPM | Go to Step 9 | Go to Step 19 | |||||||||||||
9 |
Does shift solenoid 1 click when commanded ON? | -- | Go to Step 10 | Go to Step 21 | ||||||||||||
10 | Command shift solenoid 3 ON and OFF with a scan tool. Does shift solenoid 3 click when commanded ON and OFF? | -- | Go to Step 11 | Go to Step 22 | ||||||||||||
11 | Command shift solenoid 5 ON and OFF with a scan tool. Does shift solenoid 5 click when commanded ON and OFF? | -- | Go to Step 12 | Go to Step 23 | ||||||||||||
12 | Perform a line pressure test. Refer to Line Pressure Check . Is the action complete? | -- | Go to Step 13 | -- | ||||||||||||
13 |
Did you find excessive amounts of sediment? | -- | Go to Step 18 | Go to Step 16 | ||||||||||||
14 | Inspect the control valve body assembly (39) for the following conditions:
Did you find any of the above conditions? | -- | Go to Step 24 | Go to Step 17 | ||||||||||||
15 | Inspect the control valve body assembly (39) for the following conditions:
Did you find any of the above conditions? | -- | Go to Step 24 | Go to Step 17 | ||||||||||||
16 | Inspect the control valve body assembly (39) for the following conditions:
Did you find any of the above conditions? | -- | Go to Step 24 | Go to Step 17 | ||||||||||||
17 | Has the control valve body been serviced within the past 3 months or 4 828 km (3,000 mi)? | -- | Go to Step 18 | Go to Step 24 | ||||||||||||
18 | Inspect the following items:
Is the action complete? | -- | Go to Step 25 | -- | ||||||||||||
19 | Replace the input shaft speed sensor (73). Refer to Input Speed Sensor Replacement . Is the replacement complete? | -- | Go to Step 27 | -- | ||||||||||||
20 | Replace the output shaft speed sensor (62). Refer to Output Speed Sensor Replacement . Is the replacement complete? | -- | Go to Step 27 | -- | ||||||||||||
21 | Replace the reverse, 1st shift solenoid valve assembly (S1) - black (310). Is the replacement complete? | -- | Go to Step 27 | -- | ||||||||||||
22 | Replace the 1-2, 2-3, reverse shift solenoid valve assembly (S3) - dark gray (300). Is the replacement complete? | -- | Go to Step 27 | -- | ||||||||||||
23 | Replace the reverse shift solenoid valve assembly (S5) - green (305). Is the replacement complete? | -- | Go to Step 27 | -- | ||||||||||||
24 | Repair or replace the control valve body assembly (39). Refer to Control Valve Body Cover Replacement . Is the action complete? | -- | Go to Step 27 | -- | ||||||||||||
25 | Repair or replace the transmission. Refer to Transmission Replacement . Is the action complete? | -- | Go to Step 26 | -- | ||||||||||||
26 |
Important: The Reset Trans Adapts function will clear all adapt cells. This may affect transmission performance. The TCM will update the adapt cell values as the vehicle is driven.
Did you complete the above procedures? | -- | Go to Step 27 | -- | ||||||||||||
27 | Perform the following procedure in order to verify the repair:
Does the DTC reset? | -- | Go to Step 2 | Go to Step 28 | ||||||||||||
28 | With the scan tool, observe the stored information, capture info and DTC info. Does the scan tool display any DTCs that you have not diagnosed? | -- | System OK |