2001 INFINITI QX4 IDX

SEL255W
Fail-safe SystemNBEL0217DESCRIPTIONNBEL0217S01When the fail-safe system senses a malfunction, it deactivates
ASCD operation. The SET indicator in the combination meter will
then flash.
MALFUNCTION DETECTION CONDITIONSNBEL0217S02
Detection conditionsASCD operation during malfunc-
tion detection
IASCD steering (RESUME/ACCEL, CANCEL, SET/COAST) switch is stuck.
IVacuum motor ground circuit or power circuit is open or shorted.
IAir valve ground circuit or power circuit is open or shorted.
IRelease valve ground circuit or power circuit is open or shorted.
IVehicle speed sensor is faulty.
IASCD control unit internal circuit is malfunctioning.IASCD is deactivated.
IVehicle speed memory is can-
celed.
IASCD brake switch or stop lamp switch is faulty.IASCD is deactivated.
IVehicle speed memory is not
canceled.
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AUTOMATIC SPEED CONTROL DEVICE (ASCD)
Fail-safe System
EL-229

SEL417V
FAIL-SAFE SYSTEM CHECK=NBEL0218S021. Turn ignition switch to ON position.
2. Turn ASCD main switch to ON and check if the SET indicator
blinks.
If the indicator lamp blinks, check the following.
IASCD steering switch. Refer to EL-234.
SEL767P
3. Drive the vehicle at more than 40 km/h (25 MPH) and push
SET/COAST switch.
If the indicator lamp blinks, check the following.
IVehicle speed sensor. Refer to EL-235.
IASCD pump circuit. Refer to EL-235.
IReplace control unit.
SAT797A
4. Depress brake pedal slowly (brake pedal should be depressed
more than 5 seconds).
If the indicator lamp blinks, check the following.
IASCD brake/stop lamp switch. Refer to EL-233.
5. END. (System is OK.)
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AUTOMATIC SPEED CONTROL DEVICE (ASCD)
Trouble Diagnoses (Cont'd)
EL-231

ASCD BRAKE/STOP LAMP SWITCH CHECK=NBEL0218S04
1 CHECK ASCD BRAKE SWITCH CIRCUIT
1. Disconnect ASCD control unit harness connector.
2. Turn ignition switch ON.
3. Check voltage between ASCD control unit harness connector terminal 8 and ground.
SEL258WD
OK or NG
OK©GO TO 2.
NG©Check the following.
IASCD brake switch
Refer to ªElectrical Component Inspectionº (EL-239).
IPark/neutral position switch
Refer to ªElectrical Component Inspectionº (EL-239).
IPark/neutral position relay
IHarness for open or short
2 CHECK STOP LAMP SWITCH CIRCUIT
1. Disconnect ASCD control unit harness connector.
2. Check voltage between ASCD control unit harness connector terminal 23 and ground.
SEL259WB
Refer to wiring diagram in EL-226.
OK or NG
OK©ASCD brake/stop lamp switch is OK.
NG©Check the following.
I10A fuse [No. 14, located in the fuse block (J/B)]
IHarness for open or short between ASCD control unit and stop lamp switch
IHarness for open or short between fuse and stop lamp switch
IStop lamp switch
Refer to ªElectrical Component Inspectionº (EL-239).
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AUTOMATIC SPEED CONTROL DEVICE (ASCD)
Trouble Diagnoses (Cont'd)
EL-233

VEHICLE SPEED SENSOR CHECK=NBEL0218S06
1 CHECK SPEEDOMETER OPERATION
Does speedometer operate normally?
Ye s©GO TO 2.
No©Check speedometer and vehicle speed sensor circuit. Refer to wiring diagram in EL-228.
2 CHECK VEHICLE SPEED INPUT
1. Apply wheel chocks and jack up drive wheel.
2. Disconnect ASCD control unit harness connector.
3. Check voltage between control unit terminal 22 and ground with turning drive wheel slowly by hand.
SEL263WB
Refer to wiring diagram in EL-227.
Ye s©Vehicle speed sensor is OK.
No©Check harness for open or short between ASCD control unit terminal 22 and combination
meter terminal 13.
ASCD PUMP CIRCUIT CHECKNBEL0218S07
1 CHECK ASCD PUMP
1. Disconnect ASCD pump connector.
2. Measure resistance between ASCD pump terminals 1 and 2, 3, 4.
SEL262WB
Refer to wiring diagram in EL-227.
OK or NG
OK©GO TO 2.
NG©Replace ASCD pump.
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AUTOMATIC SPEED CONTROL DEVICE (ASCD)
Trouble Diagnoses (Cont'd)
EL-235

ASCD ACTUATOR/PUMP CHECK=NBEL0218S08
1 CHECK VACUUM HOSE
Check vacuum hose (between ASCD actuator and ASCD pump) for breakage, cracks or fracture.
MEL402G
OK or NG
OK©GO TO 2.
NG©Repair or replace hose.
2 CHECK ASCD WIRE
Check wire for improper installation, rust formation or breaks.
OK or NG
OK©GO TO 3.
NG©Repair or replace wire. Refer to ªASCD Wire Adjustmentº (EL-240).
3 CHECK ASCD ACTUATOR
1. Disconnect vacuum hose from ASCD actuator.
2. Connect the hose of hand vacuum pump to ASCD actuator.
SEL264W
OK or NG
OK©GO TO 4.
NG©Replace ASCD actuator.
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AUTOMATIC SPEED CONTROL DEVICE (ASCD)
Trouble Diagnoses (Cont'd)
EL-237

SEL302X
Electrical Component Inspection=NBEL0219ASCD BRAKE SWITCH AND STOP LAMP SWITCHNBEL0219S02
ConditionContinuity
ASCD brake
switchStop lamp switch
When brake pedal is depressed No Yes
When brake pedal is released Yes No
Check each switch after adjusting brake pedal Ð refer to BR-14,
ªBRAKE PEDAL AND BRACKETº.
SEL303X
PARK/NEUTRAL POSITION SWITCHNBEL0219S03
A/T selector lever positionContinuity
Between terminals 1 and 2
ªPº Yes
ªNº Yes
Except ªPº and ªNº No
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AUTOMATIC SPEED CONTROL DEVICE (ASCD)
Electrical Component Inspection
EL-239

System DescriptionNBEL0102Power is supplied at all times
Ifrom 40A fusible link (letterf, located in the fuse and fusible link box)
Ito circuit breaker terminal 1
Ithrough circuit breaker terminal 2
Ito power window relay terminal 3,
Ito front power window main switch terminal 4, and
Ito front power window switch RH terminal 6.
With ignition switch in ON or START position, power is supplied
Ithrough 7.5A fuse [No. 11, located in the fuse block (J/B)]
Ito power window relay terminal 2, and
Ito smart entrance control unit terminal 33.
Ground is supplied to power window relay terminal 1
Ithrough body grounds M4, M66 and M147.
The power window relay is energized and power is supplied
Ithrough power window relay terminal 5
Ito front power window main switch terminal 11,
Ito front power window switch RH terminal 13,
Ito rear power window switch LH and RH terminals 5.
MANUAL OPERATIONNBEL0102S01Front Door LHNBEL0102S0101Ground is supplied
Ito front power window main switch terminal 5
Ithrough body grounds M77 and M111.
WINDOW UP
When the front LH switch in the front power window main switch is pressed in the up position, power is sup-
plied
Ito front power window regulator LH terminal 1
Ithrough front power window main switch terminal 2.
Ground is supplied
Ito front power window regulator LH terminal 3
Ithrough front power window main switch terminal 3.
Then, the motor raises the window until the switch is released.
WINDOW DOWN
When the LH switch in the front power window main switch is pressed in the down position, power is supplied
Ito front power window regulator LH terminal 3
Ithrough front power window main switch terminal 3.
Ground is supplied
Ito front power window regulator LH terminal 1
Ithrough front power window main switch terminal 2.
Then, the motor lowers the window until the switch is released.
Front Door RHNBEL0102S0102Ground is supplied
Ito front power window main switch terminal 5
Ithrough body grounds M77 and M111.
NOTE:
Numbers in parentheses are terminal numbers, when power window switch is pressed in the UP and DOWN
positions respectively.
FRONT POWER WINDOW MAIN SWITCH OPERATION
When front RH switch in the front power window main switch is pressed UP or DOWN, a signal is supplied
Ithrough front power window main switch terminal 8
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POWER WINDOW
System Description
EL-241

Ito power window relay terminal 1
Ithrough body grounds.
When power and ground are supplied, the power window relay continues to be energized, and the power win-
dow can be operated.
The retained power operation is canceled when the driver or passenger side door is opened.
INTERRUPTION DETECTION FUNCTIONNBEL0102S05Front power window main switch and front power window switch RH monitor the power window regulator motor
operation and the power window position (full closed or other) for driver's and passenger's power window by
the signals from encoder and limit switch in front power window regulator LH or RH.
When front power window main switch or front power window switch RH detects interruption during the fol-
lowing close operation in the driver's or front passenger's side door,
Iautomatic close operation when ignition switch is in the ªONº position
Iautomatic close operation during retained power operation
front power window main switch or front power window switch RH controls driver's or front passenger's power
window regulator motor for open and the power window will be lowered about 150 mm (5.91 in).
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POWER WINDOW
System Description (Cont'd)
EL-243