[Previous][Next]
HYDRAULIC PRESSURE TEST
Required Special Tools:
  • MB992744: Vehicle communication interface-Lite (V.C.I.-Lite)
  • MB992745: V.C.I.-Lite main harness A
  • MB992747: V.C.I.-Lite USB cable short
  • MB992748: V.C.I.-Lite USB cable long
  • MB991958: Scan Tool (M.U.T.-III Sub Assembly)
    • MB991824: Vehicles Communication Interface (V.C.I.)
    • MB991827: M.U.T.-III USB Cable
    • MB991910: M.U.T.-III Main Harness A (Vehicles with CAN communication system)
 
 
cautionThis test must be performed with the transmission fluid temperature within the range of 70 to 80°C (158 to 176°F).
1. Check the engine oil level, and add if necessary.
2. Warm up the engine, and then perform test drive for approximately 10 minutes.
3. Check the transmission fluid for leaks, level and contamination. Then top up or change if necessary.
4. Operate the parking brake securely, and then chock the wheels.
5. Connect the scan tool (M.U.T.-III), and then start the engine.
6.
warningFor safety, operators must not stand in front of and at the rear of the vehicle during this test.
cautionDuring this test, leave the brake pedal depressed fully.
Use the scan tool (M.U.T.-III) (data list item number 20: Secondary pressure) to measure the secondary pressure (line pressure) by observing the conditions listed in the hydraulic pressure table.
7. Stop the engine.
8. If not within the standard value, take necessary steps according to the hydraulic pressure test diagnosis table.
 
Hydraulic pressure table (reference value)
Transmission rangeDuring engine idlingDuring engine stall
"P", "N"0.50 MPa
(72.5 psi)		-
"R", "D", "L"0.50 - 1.18 MPa (72.5 - 171.1 psi)4.04 - 4.54 MPa (585.9 - 658.4 psi)
 

Hydraulic pressure test diagnosis table
Judgment resultProbable causeRemedy
During engine idlingLow at all ranges ("P", "R", "N", "D", "L")The hydraulic pressure delivery system or the oil pump may be faulty.
  • Worn oil pump
Replace the transaxle assembly
  • Damaged oil pump chain and sprocket
  • Defective pressure regulator valve, or deteriorated spring
Replace the valve body assembly
  • Leaks in the hydraulic pressure circuit ranging from the oil strainer via the oil pump to the pressure regulator valve
Replace the transaxle assembly
  • The engine idling speed is low.
Check the engine system, and repair or replace if necessary.
Low at certain range(s) only.Oil leaks may be present in the device or circuit relating to that range.Replace the transaxle assembly
HighSensor(s) or the pressure adjusting function may be faulty.
  • Malfunction of the accelerator pedal position sensor
Check the accelerator pedal position sensor, and repair or replace if necessary.
  • Malfunction of the oil pressure sensor
Replace the valve body assembly
  • Malfunction of the line pressure solenoid valve (stuck off, open circuit or short circuit)
  • Malfunction of the pressure regulator valve
During engine stallOil pressure does not rise from that during the engine idling.Sensor(s) or the pressure adjusting function may be faulty.
  • Malfunction of TCM
Check the TCM, and repair or replace if necessary.
  • Malfunction of the line pressure solenoid valve (stuck on or short circuit)
Replace the valve body assembly
  • Malfunction of the pressure regulator valve
Oil pressure rises, but is not within the standard value.The pressure supply system, sensor(s) or the pressure adjusting function may be faulty.
  • Worn oil pump
Replace the transaxle assembly
  • Malfunction of the line pressure solenoid valve
Replace the valve body assembly
  • Malfunction of the pressure regulator valve
Low at certain range(s) only.Oil leaks may be present in the device or circuit relating to that range.Replace the transaxle assembly