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Home >> Mazda >> 2002 >> Tribute LX, 4WD >> Repair and Diagnosis >> External Pages >> Different car >> Section 39 (Automatic Transmission - Diagnosis - GF4A-El) >> Diagnostic Tests >> DTC P0734: Incorrect 4TH Gear Ratio >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2002 Mazda Millenia and 2001 Mazda Millenia. However, it is still accessible from the selected car via links, so may be relevant.
  1. Record FREEZE FRAME PID data. Check for related service bulletins. Repair as necessary. Turn ignition off. Check ATF condition. If ATF is milky (contaminated with water) or reddish brown (deteriorated fluid), replace fluid and go to next step. If ATF condition is okay, start engine and warm to normal operating temperature. Check ATF level. Add fluid as necessary. If ATF level is okay, go to next step.
  2. Connect scan tool to DLC. Turn ignition on. Using scan tool, access shift and pressure control solenoid PIDs SHIFT A, SHIFT B, SHIFT C and LINE from PID/DATA MONITOR & RECORD menu. Actuate solenoid PIDs one at a time. An audible "click" should be heard from each solenoid. If any solenoid does not operate normally, replace faulty solenoid. See VALVE BODY under TRANSMISSION DISASSEMBLY in appropriate OVERHAUL article. If all solenoids operate normally, perform line pressure test in all gears. See HYDRAULIC PRESSURE TESTS  under PERFORMANCE TESTS. If line pressure is within specification for all gears, go to next step. See HYDRAULIC PRESSURE TEST RESULTS , if line pressure is low or high in all or any gears. Repair or replace transaxle as necessary. See appropriate OVERHAUL article.
  3. Perform stall speed test with gearshift lever in "S" position. See STALL SPEED TEST  under PERFORMANCE TESTS. Stall speed should be 2000-2500 RPM. If stall speed is within specification, go to next step. If stall speed is not within specification, remove transaxle valve body. See VALVE BODY under TRANSMISSION DISASSEMBLY in appropriate OVERHAUL article. Ensure 1-2, 2-3 and 3-4 shift valves and springs are free of binding. Repair as necessary. If shift valves and springs are okay, check 2-4 brake band and 3-4 clutches for damage. Repair or replace transaxle as necessary. See appropriate OVERHAUL article.
  4. Turn ignition off. Connect scan tool to DLC. Start engine. Using scan tool, access VS, 4GR, D SW, TURBINE and TP V PIDs from PID/DATA MONITOR & RECORD menu. Road test vehicle in "D" position (HOLD switch OFF) at 31 MPH while monitoring TURBINE PID. The following PID values must be met during road test:
    • VS PID value should be 31 MPH.
    • D SW PID value should be ON.
    • 4GR PID value should be ON.
    • TP V PID value should be 1.1-1.7 volts.

    TURBINE PID value should be about 1310 RPM. If TURBINE PID value is within specification, check connectors, terminals and wiring harnesses for intermittent concern. Repair as necessary, then go to next step. If TURBINE PID value is not within specification, replace valve body. See VALVE BODY under TRANSMISSION DISASSEMBLY in appropriate OVERHAUL article.

  5. Start engine. Warm engine and transaxle to normal operating temperature. Using scan tool, access VS, 4GR, D SW, and O/DF LP PIDs from PID/DATA MONITOR & RECORD menu. Road test vehicle to achieve VS PID value 48-64 MPH, 4GR and D SW values ON and O/DF LP value OFF for 15 seconds or more. Determine if DTC P0734 is still present. See RETRIEVING DIAGNOSTIC TROUBLE CODES  under SELF-DIAGNOSTIC SYSTEM. If serviced DTC resets, replace PCM. If DTC does not reset, repair is complete.
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