ABS INFINITI QX56 2011 Factory Service Manual

DESCRIPTIONSCS-7
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SYSTEM DESCRIPTION
DESCRIPTION
DescriptionINFOID:0000000006255998
 Hydraulic body-motion control s ystem is adopted, which makes shock absorber stroke appropriately by
hydraulic pressure according to driving scenes.
 The adoption of this system allows the reduction in a ro ll angle (i.e. vehicle body tilt angle at cornering) to
improve steering stability and ride quality during travel on level roads. Furthermore, the use of this system
improves the running performance on rough roads by shock absorption and quality tire adhesion through
maximized stroke.
Revision: 2010 May2011 QX56

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COMPONENT PARTS
COMPONENT PARTS
Component Parts LocationINFOID:0000000006255999
Component DescriptionINFOID:0000000006256000
1. Middle tube assembly RH 2. Accumulator assembly RH 3. Front tube assembly A
4. Front tube assembly B 5. Accumulator assembly LH 6. PPMU pipe A
7. PPMU assembly 8. Middle tube assembly LH 9. PPMU pipe B
10. Rear tube assembly A 11. Rear tube assembly B
:Vehicle front
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Component parts Reference
Shock absorber SCS-9, "
Shock Absorber"
AccumulatorSCS-11, "Accumulator"
PPMUSCS-10, "PPMU"
PPMU pipe A
SCS-11, "PPMU Pipe"PPMU pipe B
Revision: 2010 May2011 QX56

STRUCTURE AND OPERATIONSCS-9
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STRUCTURE AND OPERATION
Hydraulic Body-Moti on Control SystemINFOID:0000000006256001
Shock AbsorberINFOID:0000000006256002
The use of accumulator-generated pressure responsive to driving conditions or pressure generated by oil flow
to the upper/lower chamber improves the steering stabili ty at curving, in addition to the running performance
and a ride quality during off-road travel.
FRONT SIDE
Oil enters from oil inlet outlet hole (A) and flows into lower chamber (3) via outside oil path of cylinder inside.
Oil enters from oil inlet outlet hole (B) and flows into upper chamber (1). With the pressure difference between
oil flowed into the upper chamber and lower chamber, the piston (2) moves up and down and conveys a force
generated through this motion to the tires.
1. Middle tube assembly RH 2. Accumulator assembly RH 3. Front tube assembly A
4. Front tube assembly B 5. Accumulator assembly LH 6. PPMU pipe A
7. PPMU assembly 8. Middle tube assembly LH 9. PPMU pipe B
10. Rear tube assembly A 11. Rear tube assembly B
:Vehicle front
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Revision: 2010 May2011 QX56

STRUCTURE AND OPERATIONSCS-11
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When system pressure decreases, influent oil is dist ributed to both pipes by gas spring reaction force of
nitrogen gas via PPMU pipe A and PPMU pipe B to control sudden decrease in system pressure.
AccumulatorINFOID:0000000006256004
Influent oil from both front and rear shock absorbers on the outer ring flows simultaneously into the oil cham-
ber during cornering, and gas spring reaction force of ni trogen gas increases pressure, according to the influ-
ent oil level. As for inner ring side, the gas spring conv eys oil from the oil chamber to both front and rear shock
absorbers and decreases pressure, according to the oil level.
PPMU PipeINFOID:0000000006256005
PPMU and right and left tubes are connected. When oil in creases according to increase of system pressure,
increased amount of oil is sent to PPMU. When system pressure decreases, oil discharged from PPMU is sent
to right and left tubes.
1. Oil chamber 2. Bellows 3. Gas chamber
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1. Oil chamber 2. Gas chamber 3. Bellows
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SYSTEM
SYSTEM
System DiagramINFOID:0000000006256006
System DescriptionINFOID:0000000006256007
 Drivability during cornering and driving on rough road
is improved by mechanically generating oil pressure
by connecting 4 units of shock absor bers to front, rear, right, and left by piping lines of 2 systems.
 Oil filling and system diagnosis can be performed using PPMU.
OPERATING PRINCIPLE
During cornering (Front and rear wheels in the outer side of corner: compressing)
When shock absorber in the outer side of corner is compressed during cornering, oil moves along piping path
and overflowing oil from piping path flows in accumulato r in the outer side of corner. Then, pressure increases
by action of gas spring of nitrogen gas acco rding to amount of oil that flows in.
Pressure in the inner side of corner decreases, since oil is discharged from accumulator by stroke (extending
direction) of shock absorber.
The pressure difference generates stabilizer-like action to maintain balance in vehicle posture for a steady
driving at cornering.
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SYSTEMSCS-13
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During rough road driving (Front wheel LH: compressing, front wheel RH: extending, rear wheel LH: extending, rear
wheel RH: compressing)
Discharged oil from each shock absorber moves along piping
path, but oil does not overflow from piping path,
since oil moves in between each shock absorber. Oil does not flow in accumulator and system pressure does
not increase.
Since the oil from the contracted shock absorber flow s into the shock absorber upper chamber, stabilizer-like
action is not generated. This improves the adhes ion level and the running performance on rough roads.
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Revision: 2010 May2011 QX56

AIR BLEEDING METHODSCS-19
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8. Loosen needle valves A, C, and E of PPMU by approximately 2 rotations.
CAUTION:
Never loosen the needle valve more than required.
9. Install bleeder tube and drain tank to bleeder valve in upper side of rear shock absorber RH.
10. Loosen bleeder valve and bleed air while sending oil by applying pressure using suspension oil pump, and then quickly tighten air
bleeder.
CAUTION:
Be careful that oil in suspensi on oil pump is not at half or
less.
11. Repeat step 10 until no air appears in bleeder tube.
12. Tighten bleeder valve to the specified torque. Refer to SCS-32, "
FRONT TUBE ASSEMBLY : Exploded
View" (front shock absorber), SCS-39, "PPMU, MIDDLE TUBE ASSEMB LY, PPMU PIPE : Exploded
View" (upper side of rear shock absorber).
13. Perform operation according to steps 9 to 12 in the order of rear shock absorber RH (lower side) → front
shock absorber RH (upper side and lower side) → rear shock absorber LH (upper side and lower side) →
front shock absorber LH (upper side and lower side).
14. Repeat steps 9 to 13 (2nd turn).
15. Refer to the figure and send oil by applying pressure.
16. Tighten needle valves A, C, and E of PPMU to the specified torque.
17. Set knob (A) of suspension oil pump to the direction as shown in the figure and check that reading of pressure gauge is 0 MPa.
18. Remove hose of suspension oil pump.
19. Install cap of oil injection jack.
20. Install protector of PPMU. Refer to SCS-39, "
PPMU, MIDDLE
TUBE ASSEMBLY, PPMU PIPE : Exploded View".
Lower side of rear shock absorber
Tightening torque : 8.3 N·m (0.85 kg-m, 73 in-lb)
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Tightening torque : 8.3 N·m (0.85 kg-m, 73 in-lb)
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CHECK FOR MALFUNCTION
CHECK FOR MALFUNCTION
Work ProcedureINFOID:0000000006256013
CAUTION:
 Clean surrounding areas of
oil injection jack using steam before starting operation, since there may
be mud on it.
 Clean oil pressure gauge (special service tool: KV40108000) jack with steam before use.
1. Remove protector of PPMU.
2. Remove cap of oil injection jack.
3. Install an oil pressure gauge (SST: KV40108000) (A) to oil injec- tion jack.
CAUTION:
 Jack must be securely inserted until a click sound can beheard.
 Pressure reducing valve (B) of the oil pressure gauge
must be closed.
4. Loosen needle valves A, C, and E of PPMU by approximately 2 rotations.
CAUTION:
Never loosen the needle valve more than required.
5. Lift up the vehicle. CAUTION:
Check that tires never contact the ground.
6. Tighten needle valves A and C of PPMU.
7. Loosen lock nuts of needle valves B and D of PPMU and then tighten needle valves B and D.
8. Write down a value of the oil pressure gauge.
9. Lift down the vehicle. CAUTION:
Check that the lift is fully lowered.
10. Read a value of oil pressure gauge.
11. Compare difference of reading with pressure reading in step 8.
12. Tighten needle valves A, C, and E of PPMU to the specified torque.
13. Loosen needle valves B and D of PPMU by approximatel y 2 rotations and then tighten lock nut to the
specified torque.
CAUTION:
Never loosen the needle valve more than required.
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Pressure change
Pressure increases : PPMU malfunction
Pressure does not change : Shock absorber malfunction
Tightening torque : 8.3 N· m (0.85 kg-m, 73 in-lb)
Tightening torque : 20 N·m (2.0 kg-m, 15 ft-lb)
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CHECK SHOCK ABSORBER FOR MALFUNCTION
CHECK SHOCK ABSORBER
FOR MALFUNCTION
Work ProcedureINFOID:0000000006256014
CAUTION:
 Clean surrounding areas of oil injection jack using steam before starting operation, since there may
be mud on it.
 Clean suspension oil pump (special servi ce tool: KV40107700) jack with steam before use.
 Clean leak check plug (special service to ol: KV40108400) jack with steam before use.
 Check each shock absorber, one by one, in accordance with the following procedures.
1. Lift up the vehicle.
2. Remove protector of PPMU.
3. Remove cap of oil injection jack.
4. Install hose (A) of a suspension oil pump (SST: KV40107700) to oil injection jack.
CAUTION:
 Jack must be securely inserted until a click sound can be
heard.
 Pressure reducing valve (B) of the suspension oil pump
must be closed.
5. Loosen needle valves A, C, and E of PPMU by approximately 2 rotations.
CAUTION:
Never loosen the needle valve more than required.
6. Set knob (A) of suspension oil pump to the direction as shown in the figure and check that reading of pressure gauge is 0 MPa.
7. Tighten needle valves A, C, and E of PPMU.
8. Disconnect upper side pipe or lower side pipe of each shock absorber.  For front shock absorber
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Revision: 2010 May2011 QX56

CHECK SHOCK ABSORBER FOR MALFUNCTIONSCS-25
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- Disconnect upper side pipe (B) of front shock absorber.
 For rear shock absorber
- Disconnect lower side pipe (B ) of rear shock absorber.
9. Install a leak check plug (SST: KV40108400) (A) to the removed pipe and tighten the leak check plug to the specified torque.
CAUTION:
 O-ring must be free of scratches and damage.
 Piping must be kept free of the intrusion of dust and dirt.
10. Loosen lock nuts of needle valves B and D of PPMU and then tighten needle valves B and D.
11. Loosening position of needle valve of PPMU varies according to shock absorber that is che cked. Loosen needle valve of PPMU
by approximately 2 rotations, as per the following table.
CAUTION:
Never loosen the needle valve more than required.
12. Set knob (A) of suspension oil pump to the direction as shown in the figure.
13. Apply pressure of up to 2.4 MPa.
14. Go to step 15 when oil comes out from lower portion of shock absorber which pipe is removed from. Go to step 16 when oil
does not come out.
15. Replace shock absorber, since shock absorber has internal leakage. Refer to FSU-10, "
Removal and Installation" (front),
RSU-8, "
Removal and Installation" (rear).
A : Lower side pipe
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A : Upper side pipe
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Tightening torque : 5.0 N·m (0.51 kg-m, 44 in-lb)
Shock absorber Loosening position of needle valve
Front LH C
Rear LH C
Front RH A
Rear RH A
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Revision: 2010 May2011 QX56