Hydraulic Pressure Test

WARNING: This page is about a different variant/trim than selected.

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)

CAUTION: This test must be performed with the transmission fluid temperature within the range of 70 to 80°C (158 to 176°F).

Check the engine oil level, and add if necessary.
Warm up the engine, and then perform test drive for approximately 10 minutes.
Check the transmission fluid for leaks, level and contamination. Then top up or change if necessary.
Operate the parking brake securely, and then chock the wheels.
Connect the scan tool (M.U.T.-III), and then start the engine.
WARNING: For safety, operators must not stand in front of and at the rear of the vehicle during this test.

CAUTION: During 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.
Stop the engine.
If not within the standard value, take necessary steps according to the hydraulic pressure test diagnosis table.

HYDRAULIC PRESSURE REFERENCE VALUE

Transmission range	During engine idling	During 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 REFERENCE

Judgment result		Probable cause		Remedy
During engine idling	Low 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	Replace the transaxle assembly
			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. High	Oil leaks may be present in the device or circuit relating to that range.		Replace the transaxle assembly
		Sensor(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 stall	Oil 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.
		Sensor(s) or the pressure adjusting function may be faulty.	Malfunction of the line pressure solenoid valve (stuck on or short circuit) Malfunction of the pressure regulator valve Replace the valve body assembly
	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
	Oil pressure rises, but is not within the standard value.		Malfunction of the line pressure solenoid valve Malfunction of the pressure regulator valve	Replace the valve body assembly
	Low at certain range(s) only.	Oil leaks may be present in the device or circuit relating to that range.		Replace the transaxle assembly