Diagnostic Procedure (Caravan & Voyager)
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DTC P0740 will set if torque converter does not lock up or unlock properly. This DTC may also set if vehicle is driven over mountainous terrain. Possible causes are open fused ignition switch output circuit, faulty or stuck TCC solenoid, faulty torque converter, dirty transaxle fluid, low transaxle fluid level or non-standard vehicle configuration.
1.Turn ignition on. Using scan tool, read DTCs. If GLOBAL GOOD TRIP is displayed and is equal to zero, go to next step. If GLOBAL GOOD TRIP is not displayed or is not equal to zero, test is complete. 2.Turn ignition off. Tee in a 300 psi (21 kg/cm 2 ) pressure gauge to transaxle oil cooler inlet line. Ensure pressure gauge hose is long enough so gauge can be monitored during test drive. Test drive vehicle in Drive at 50 MPH while monitoring scan tool and pressure gauge. Pressure gauge should indicate about 15 psi (1.0 kg/cm 2 ) until lock-up is achieved. As scan tool indicates lock-up, pressure gauge reading should jump. If operation is as specified, go to next step. If operation is not as specified, torque converter or TCC solenoid is faulty. Repair as necessary. 3.Turn ignition off. Check transaxle fluid for improper level or for presence of any debris. Repair as necessary. If transaxle fluid level and condition are okay, go to next step. 4.Turn ignition off. Disconnect TCC solenoid harness connector. Turn ignition on. Using scan tool, measure voltage on fused ignition switch output circuit at TCC solenoid harness connector. See WIRING DIAGRAMS . If voltage is greater than 10 volts, go to next step. If voltage is 10 volts or less, repair high resistance or open circuit. 5.Turn ignition off. Measure resistance of TCC solenoid. If resistance is 30-50 ohms, go to next step. If resistance is not as specified, replace TCC solenoid. 6.Test drive vehicle and maintain 50 MPH as indicated on scan tool. Achieve lock-up and wait 10 seconds. Record engine RPM. If engine speed was 2150-2250 RPM, go to next step. If engine RPM was not as specified, differential, output shaft or gear train is most likely at fault. Repair as necessary. 7.Turn ignition off. Remove Vehicle Speed Sensor (VSS). Inspect for damage. Ensure front tires are correct size for vehicle. Repair as necessary. If no problems are found, test is complete.
Tuesday, April 13th, 2010 AT 2:34 PM