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Diagnostic Procedure

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DIAGNOSTIC TEST REFERENCE - P0731-GEAR RATIO ERROR IN 1ST

TEST ACTION APPLICABILITY
1
NOTE: Low fluid level can be the cause of many transmission problems. If the fluid level is low locate and repair the leak then check and adjust the fluid level per the Service Information.
NOTE: Always perform diagnostics with a fully charged battery to avoid false symptoms.
With the DRBIII®, read the engine DTC's. Check and repair all engine DTC's prior to performing transmission symptom diagnostics.With the DRBIII®, read Transmission DTC's. Record all DTC's and 1 Trip Failures.
NOTE: Diagnose 1 Trip Failures as a fully matured DTC.
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors.Repair as necessary.Perform the Shift Lever Position Test. If the test does not pass, refer to Symptom test for P0706 CHECK SHIFTER SIGNAL .For Gear Ratio DTC's, check and record all CVI's.Most DTC's set on start up but some must be set by driving the vehicle such that all diagnostic monitors have run.
NOTE: Verify the flash level of the transmission controller. Some problems are corrected by software upgrades to the transmission controller.
NOTE: Check for applicable TSB's related to the problem.
Perform this procedure prior to Symptom diagnosis.ContinueGo To 2		 All
2 With the DRBIII®, check for other transmission DTC's
If any of these DTC's are present, perform their respective tests first.
Are DTC's P0944, P0715, P0720, P1794, P0867, P0932, P0868, or P0869 present also?
Yes --> Refer to the TRANSMISSION CATEGORY  and perform the appropriate symptom. If any of these DTCs are present, they will cause a Speed Ratio Error. Perform the test for P0944 first if it is present.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .
No --> Go To 3		 All
3 With the DRBIII®, perform the 1st Gear Clutch Test. Follow the instructions on the DRBIII®.
Increase the throttle angle or TPS Degree to 30°, for no more than a few seconds.
CAUTION: Do not overheat the transmission.

Did the Clutch Test pass, Input Speed remain at zero?
Yes --> Go To 4
No --> Go To 5		 All
4 The conditions to set this DTC are not currently present.
With the DRBIII®, check the EATX DTC EVENT DATA to help identify the conditions in which the DTC was set.
IF the DTC Event Data shows fault P0731 was set in park or in park, reverse, or neutral, replace the PCM in NGC vehicles or TCM in EATX vehicles.
IF the DTC Event Data shows fault P0731 was set with input RPM = zero, check the Input Speed Sensor and related wiring.
IF the DTC Event Data shows fault P0731 was set with line pressure significantly below the desired line pressure, check oil level, primary oil filter and seal, sticking main regulator valve in pump.
IF the DTC Event Data shows fault P0731 was set with UD pressure switch open, but line pressure matches desired line pressure, air check UD Clutch passage for leakage and if OK, replace Transmission Solenoid/TRS Assembly.
Check the gearshift linkage adjustment.
Intermittent Gear Ratio DTCs can be set by problems in the Input and Output Speed Sensor circuits and/or Speed Sensor Ground circuit.
Remove the Starter Relay.
Check the speed sensor wiring and connectors for good connection, then perform a wiggle test using the Transmission Simulator, Miller tool # 8333.
NOTE: Failure to remove the Starter Relay can cause a Transmission - No Response condition.

Gear ratio DTC's can also be set under extreme temperature conditions, this is usually caused by an internal problem.
Verify if the problem is only experienced under extreme hot or cold conditions.
Were there any problems found.
Yes --> Repair as necessary.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .
No --> Test Complete.		 All
5 Repair the transmission as necessary. If there were any line pressure DTC's present along with this DTC, make sure to inspect the Transmission Oil Pump and Pressure Control Solenoid per the Service Information.
If the DTC's P0876 and/or P0875 are also present, replace the Transmission Solenoid/TRS Assembly in addition to necessary internal repairs.
If there are no possible causes remaining, view repair.
Repair
Repair internal transmission per the Service Information. Inspect, cut UD piston seal, failed overrunning clutch, cut UD accumulator seal ring, broken UD accumulator piston, broken reaction shaft support seal ring or dribbler orifice, bleed orifice.
Perform 45RFE/545RFE TRANSMISSION VERIFICATION TEST - VER 1 .		 All
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