P0733-GEAR RATIO ERROR IN 3RD Theory of Operation
The Transmission Control Module (TCM) constantly calculates the transmission ratio based on the input speed sensor 1 and 2 (N2-N3) signals and the calculated output shaft speed. The intent of this diagnostic is to detect if the transmission is slipping or an invalid gear ratio is present.
- When Monitored: Engine RPM greater than 450 RPM , output speed greater than 180 RPM , no N2 - N3 input speed sensor errors present, no gear selector lever errors present, no ABS system errors, and all wheel speeds above 450 RPM .
- Set Condition: No shifting operation and detected gear is not the actual gear. No shifting operation - detected (calculated) gear is less than actual (expected) gear, no plausible gear is calculated, actual turbine speed - calculated turbine speed is greater than 300 RPM or calculated transmission ratio is above threshold. During an Upshift detected (calculated) gear is less than actual (expected) gear. During Downshift - detected (calculated) gear is less than actual (expected) gear.
- LOW TRANSMISSION FLUID
- OTHER TRANSMISSION DTC's PRESENT
- INTERNAL TRANSMISSION FAILURE
Always perform the NAG1 Pre-Diagnostic Troubleshooting procedure before proceeding. See: Transmission Control Systems\Testing and Inspection\Procedures\NAG1 Automatic TransmissionDiagnostic Test
CHECK FOR OTHER TRANSMISSION DTC's
With the scan tool, check transmission DTC's
Are there any solenoid and/or solenoid supply voltage DTC's present?YES >>
Refer to the Transmission category and perform the appropriate symptom(s).NO >>
Go To 2
CHECK TRANSMISSION FLUID LEVEL
Check the transmission fluid level.
Is the fluid level correct?YES >>
Go To 3NO >>
Properly adjust the fluid level.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. See: Verification Tests\Transmission Verification Test
CHECK IF DTC IS CURRENT
With the scan tool, record the Environmental Data and erase Transmission DTC's.
If the TCM
detects and stores a DTC, the TCM also stores the vehicles operating conditions under which the DTC originally set and is located in scan tool under Environmental Data. Before erasing any stored DTC's, record any available data to assist in duplicating the conditions in which the DTC originally set.
Using the Environmental Data recorded earlier, test drive the vehicle while trying to duplicate the conditions in which the DTC originally set.
Did the DTC P0733-GEAR RATIO ERROR IN 3RD reset?YES >>
Repair internal transmission as necessary.
Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. See: Verification Tests\Transmission Verification TestNO >>
Go To 4
INTERMITTENT WIRING AND CONNECTORS
The conditions necessary to set this DTC are not present at this time.
Using the schematics as a guide, inspect the wiring and connectors specific to this circuit.
Wiggle the wiring and connectors while checking for any possible open or shorted circuits.
Check for any Service Information Tune-ups or Technical Service Bulletins that may apply.
Were there any problems found?YES >>
Repair as necessary.Perform NAG1 TRANSMISSION VERIFICATION TEST - VER 1. See: Verification Tests\Transmission Verification TestNO >>