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Diagnostic Procedures

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  1. Ensure fluid level is correct. Connect scan tool to DLC. Turn ignition switch to ON position. DO NOT start engine. Using scan tool, record freeze frame and failure records for reference. Data will be lost when DTCs are cleared later in this test.
  2. Start engine and let idle. Apply parking brake. While observing scan tool, shift transmission into each gear position. If gear position matches Transmission Fluid Pressure (TFP) position switch A/B/C display on scan tool, go to next step. If gear position does not match Transmission Fluid Pressure (TFP) position switch A/B/C display on scan tool, diagnose Transmission Fluid Pressure (TFP) position switch. Switch is also referred to as Pressure Switch Assembly (PSA). See COMPONENT TESTS . Also see DTC P1810 .
  3. Perform line pressure check procedure. See HYDRAULIC PRESSURES TESTS in AUTO TRANS OVERHAUL article. If line pressure is within specifications, go to next step. If line pressure is not within specifications, refer to TROUBLE SHOOTING in AUTO TRANS OVERHAUL article for diagnosis.
  4. Drive vehicle in "D4" while TCC is engaged. If TCC slip speed is more than 110-130 RPM for 10 seconds while TCC is engaged above throttle angle of 12 percent, go to next step. If TCC slip speed is less than 110-130 RPM for 10 seconds, see DIAGNOSTIC AIDS.
  5. Drive vehicle in "D3". Using scan tool, command TCC on. If TCC slip speed is more than 110-130 RPM for 10 seconds while TCC is engaged above throttle angle of 12 percent, refer to TROUBLE SHOOTING in AUTO TRANS OVERHAUL article for diagnosis. If TCC slip speed is less than 110-130 RPM for 10 seconds, go to next step.
  6. Repeat step 4). If results are still the same, remove transmission oil pan. Check for debris or fluid contamination. If debris is visible or contamination exists, refer to AUTO TRANS OVERHAUL article for diagnosis. If debris is not visible and fluid is okay, check for contaminated shift solenoids or damaged solenoid seals. Repair as necessary, then go to next step. If solenoids are okay, check for contaminated or sticking 1-2, 2-3 or 3-4 shift valves. Repair as necessary, then go to next step. If results in step 4) are not the same, check for contaminated or sticking 1-2, 2-3 or 3-4 shift valves.
  7. After repair is complete, select DTC on scan tool. Select "Clear Info" function. Drive vehicle in 4th gear with TCC commanded on. VCM must detect a slip of -25 to 30 RPM for more than 10 seconds. Select "Specific DTC" and enter DTC "P1870". If DTC P1870 is not present, repair is complete. If DTC P1870 is still present, repeat test.
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