P1723 — Gear 3 incorrect Ratio

Diagnostic algorithm

1. Connect a diagnostic scanner, record freeze-frame and all transmission-related codes; note live data while reproducing the fault.
2. Verify transmission fluid level and condition; correct level and replace fluid/filter if contaminated or severely degraded.
3. Check for related codes (speed sensor, solenoid, pressure) and address them first; clear codes and retest.
4. With road test and live data: log engine RPM, input speed and output speed during shift to 3rd. Calculate actual ratio (input speed ÷ output speed) and compare to expected for 3rd gear documented by manufacturer.
5. If ratio indicates slip (input high, output low) inspect shift solenoids and perform solenoid electrical tests; if solenoids commanded correctly but hydraulic response poor, perform line pressure test.
6. Inspect wiring/connectors for input/output speed sensors and solenoids; repair any shorts, opens, or corrosion. Replace faulty sensors if signals are intermittent or out of spec.
7. If electrical and hydraulic tests are normal but ratio still incorrect, suspect internal mechanical wear: remove valve body/inspect clutch packs, bands, planetary gears, and shift forks. Repair or replace worn components.
8. If internal mechanical faults are repaired, reassemble using manufacturer procedures, refill with correct fluid, clear codes, and perform final road test with data logging to confirm proper 3rd gear ratio and no reoccurrence.
9. If no mechanical fault found and signals/controls are correct, consider TCM reflash or replacement as a last resort after verifying network and power integrity.