ABS INFINITI QX4 2005 Factory Service Manual

ACS-1
AUTO CRUISE CONTROL SYSTEM
K ELECTRICAL
CONTENTS
C
D
E
F
G
H
I
J
L
M
SECTION ACS
A
B
ACS
Revision: October 20052005 QX56
ASCD
AUTOMATIC SPEED CONTROL DEVICE (ASCD) ..... 3
Description ............................................................... 3
ICC
PRECAUTIONS .......................................................... 4
Precautions for Supplemental Restraint System
(SRS) “AIR BAG” and “SEAT BELT PRE-TEN-
SIONER” .................................................................. 4
Precautions for ICC System Service ........................ 4
Wiring Diagrams and Trouble Diagnosis .................. 4
PREPARATION ........................................................... 5
Special Service Tool ................................................. 5
DESCRIPTION ............................................................ 6
Outline ...................................................................... 6
VEHICLE-TO-VEHICLE DISTANCE CONTROL
MODE ................................................................... 6
CONVENTIONAL (FIXED SPEED) CRUISE
CONTROL MODE ................................................. 6
BRAKE ASSIST (WITH PREVIEW FUNCTION) ..... 6
System Diagram ....................................................... 6
Components Description .......................................... 7
CAN Communication ................................................ 7
SYSTEM DESCRIPTION ...................................... 7
Switch Operation ...................................................... 7
ICC System Display ................................................. 8
ACTION TEST ............................................................ 9
ICC System Running Test ........................................ 9
VEHICLE-TO-VEHICLE DISTANCE CONTROL
MODE ................................................................... 9
CONVENTIONAL (FIXED SPEED) CRUISE
CONTROL MODE ............................................... 10
LASER BEAM AIMING ADJUSTMENT ................... 12
Outline of Laser Beam Aiming Adjustment Proce-
dure ........................................................................ 12
Preparation ............................................................. 12
Setting up the ICC Target Board ............................ 12
ADJUSTING HEIGHT OF THE TARGET ............ 12
ADJUSTING THE POSITION OF THE TARGET BOARD STRING ................................................. 13
POSITIONING THE TARGET ............................. 13
Sensor Adjustment ................................................. 14
CHECK AFTER THE ADJUSTMENT .................. 17
ELECTRICAL UNITS LOCATION ............................ 18
Component Parts and Harness Connector Location ... 18
WIRING DIAGRAM ................................................... 19
Schematic ............................................................... 19
Wiring Diagram — ICC — ...................................... 20
TERMINALS AND REFERENCE VALUE ................. 24
Terminals and Reference Values for ICC Unit ........ 24
Terminals and Reference Values for ICC Sensor ... 24
TROUBLE DIAGNOSIS — GENERAL DESCRIP-
TION .......................................................................... 25
Work Flow ............................................................... 25
CONSULT-II Function (ICC) ................................... 26
CONSULT-II OPERATION ................................... 26
WORK SUPPORT ............................................... 27
SELF-DIAGNOSTIC RESULTS ........................... 28
DATA MONITOR ................................................. 28
ACTIVE TEST ..................................................... 29
Self-Diagnostic Function ......................................... 31
WITH CONSULT-II .............................................. 31
WITHOUT CONSULT-II ....................................... 32
SELF-DIAGNOSIS BY ICC SYSTEM DISPLAY
WILL NOT RUN ................................................... 33
TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC
ITEMS ........................................................................ 36
Diagnostic Trouble Code (DTC) Chart ................... 36
DTC 11 CONTROL UNIT ....................................... 37
DTC 12 VDC CONTROL UNIT ............................... 37
DTC 20 CAN COMM CIRCUIT ............................... 38
DTC 31 POWER SUPPLY CIR1, DTC 34 POWER
SUPPLY CIR2 ........................................................ 38
DTC 41 VHCL SPEED SE CIRC ............................ 39
DTC 43 VDC/TCS/ABS CIRC ................................ 39
DTC 45 BRAKE SW/STOP L SW ........................... 40
DTC 46 OPERATION SW CIRC ............................. 41
DTC 74 LASER BEAM OFF CNTR ........................ 43
DTC 90 STOP LAMP RLY FIX ............................... 43

DESCRIPTION
ACS-7
[ICC]
C
D
E
F
G
H
I
J
L
MA
B
ACS
Revision: October 20052005 QX56
Components DescriptionEKS00BLI
CAN CommunicationEKS00BLJ
SYSTEM DESCRIPTION
Refer to LAN-5, "CAN COMMUNICATION" .
Switch OperationEKS00BLK
The system is operated by a master ON/OFF switch and four control switches, all mounted on the steering
wheel.
ComponentVehicle-to-vehicle
distance control
modeConventional
(fixed speed)
cruise control
modeBrake assist
(with preview
brake)Description
ICC unit×××Controls vehicle speed through ECM via CAN
communication.
ICC sensor××Irradiate laser beam, and receives reflected
laser beam to measure distance from preceding
vehicle.
ECM×××Transmits throttle position signal and ICC steer-
ing switch signal to ICC unit.
ABS actuator and electric
unit (control unit)×××Transmits wheel speed signal to ICC unit.
Operates brake booster based on CAN commu-
nication.
Brake pressure sensor××Detects fluid pressure in master cylinder.
Brake booster××Adjusts brake fluid pressure based on command
from ABS actuator and electric unit (control
unit).
BCM×Transmit front wiper request signal to ICC unit.
TCM××Transmits gear position signal and output shaft
revolution signal to ICC unit.
No. Switch name Description
1 ACCEL/RES switch Resumes set speed or increases speed incrementally.
2 COAST/SET switch Sets desired cruise speed, reduces speed incrementally.
3 ON/OFF switch Master switch to activate the system.
SKIA5973E

TROUBLE DIAGNOSIS — GENERAL DESCRIPTION
ACS-27
[ICC]
C
D
E
F
G
H
I
J
L
MA
B
ACS
Revision: October 20052005 QX56
6. Touch “WORK SUPPORT”, “SELF-DIAG RESULTS”, “DATA
MONITOR”, "CAN DIAG SUPPORT MNTR", “ACTIVE TEST” or
“ECU PART NUMBER” on selection screen.
WORK SUPPORT
Work Item
Cause of Auto-Cancel
1. Touch “WORK SUPPORT” on "SELECT DIAG MODE" screen.
2. Touch “CAUSE OF AUTO-CANCEL” on "SELECT WORK ITEM"
screen.
3. Cause of automatic cancellation screen will be shown.
4. The last five causes of automatic cancellation of ICC system will
be displayed.
Possible Causes of "Auto-Cancel"
Laser Beam Adjust
For details, refer to ACS-12, "LASER BEAM AIMING ADJUSTMENT" .
BCIA0031E
Operation Function
CAUSE OF AUTO-CANCEL Indicates causes of automatic cancellation of the ICC system.
LASER BEAM ADJUST Outputs laser beam, calculates dislocation of the beam, and indicates adjustment direction.
SKIA6191E
Cause of cancellation Description
OPERATING WIPER Windshield wipers were operated at HI or LO speed operation.
OPERATING ABS ABS function was operated.
OPERATING TCS TCS function was operated.
OPERATING VDC VDC function was operated.
ECM CIRCUIT ECM did not permit ICC operation.
OPE SW VOLT CIRC Voltage outside the standard was detected.
LASER SUN BEAM Intense light such as sunlight entered ICC sensor light sensing part.
LASER TEMP Temperature around ICC sensor became low.
WHL SPD ELEC NOISE Wheel speed sensor signal caught electromagnetic noise.
OP SW DOUBLE TOUCH ICC steering switches were pressed at the same time.
VDC/TCS OFF SW VDC OFF switch was pressed.
WHEEL SPD UNMATCH Wheel speed became different from AT vehicle speed.
TIRE SLIP Wheel slipped.
PKB SW ON Parking brake is applied.
IGN LOW VOLT Power supply voltage became low.
NO RECORD—

ACS-36
[ICC]
TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
Revision: October 20052005 QX56
TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMSPFP:00000
Diagnostic Trouble Code (DTC) ChartEKS00BLZ
×:Applicable
DTC
No.CONSULT-II screen termsICC sys-
tem
warning
lampFail-safe
Malfunctions detected where...Refer-
ence
page Vehicle-
to-vehi-
cle dis-
tance
control
modeConven-
tional
(fixed
speed)
cruise
control
modeBrake
assist
(with pre-
view
function)
11 CONTROL UNIT××××

ICC unit internal malfunctionACS-37
12 VDC CONTROL UNIT××××

VDC malfunction

Brake booster signal harness is
open or shortedACS-37
20 CAN COMM CIRCUIT××××
ICC unit detected CAN communi-
cation malfunctionACS-38
31 POWER SUPPLY CIR1××××
ICC unit power supply voltage is
excessively low (less than 8V)ACS-38
34 POWER SUPPLY CIR2××××
ICC unit power supply voltage is
excessively high.ACS-38
41 VHCL SPEED SE CIRC××××

Wheel sensor malfunction

ABS actuator and electric unit
(control unit) malfunction

A/T vehicle speed sensor mal-
function

TCM malfunctionACS-39
43 VDC/TCS/ABS CIRC××××
VDC/TCS/ABS system malfunc-
tionACS-39
45 BRAKE SW/ STOP L SW××××

ICC brake switch or stop lamp
switch harness is open or shorted

ICC brake switch or stop lamp
switch is stuck to OFF

ICC brake switch or stop lamp
switch is stuck to ONACS-40
46 OPERATION SW CIRC×××

ICC steering switch harness or
spiral cable is open or shorted

ICC steering switch malfunctionACS-41
74 LASER BEAM OFF CNTR×× ×
Laser beam of ICC sensor is off
the aiming pointACS-43
90 STOP LAMP RLY FIX×× ×
Normally open terminal of stop
lamp relay is stuckACS-43
92 ECM CIRCUIT××××

ECM malfunction

Accelerator pedal position sensor
malfunction

ICC unit malfunctionACS-48
96 NP RANGE×××

Park/neutral position switch har-
ness is open or shorted

Park/neutral position switch mal-
function

TCM malfunctionACS-48
97 AT CIRCUIT×××
TCM malfunctionACS-49

TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
ACS-37
[ICC]
C
D
E
F
G
H
I
J
L
MA
B
ACS
Revision: October 20052005 QX56
NOTE: DTC 55 will display when no malfunction is detected.
DTC 11 CONTROL UNITEKS00BM0
1. DIAGNOSTIC CHECK
Are any items other than “DTC 11 CONTROL UNIT” indicated on self-diagnosis display?
YES or NO
YES >> Repair or replace as necessary. Erase DTC and perform ICC system running test. Refer to ACS-
9, "ICC System Running Test" . Then perform self-diagnosis of ICC system again.
NO >> Replace ICC unit. Refer to ACS-60, "
ICC Unit" . Erase DTC and perform ICC system running test.
Refer to ACS-9, "
ICC System Running Test" . Then perform self-diagnosis of ICC system again.
DTC 12 VDC CONTROL UNITEKS00BM1
1. DIAGNOSIS CHECK
With CONSULT-II
Perform self-diagnosis of ABS actuator and electric unit (control unit). Is malfunction indicated?
YES or NO
YES >> Repair or replace as necessary. Erase DTC and perform ICC system running test. Refer to ACS-
9, "ICC System Running Test" . Then perform self-diagnosis of ICC system again.
NO >> GO TO 2.
2. CHECK CONNECTOR ICC UNIT AND ABS ACTUATOR AND ELECTRIC UNIT (CONTROL UNIT)
1. Turn ignition switch OFF.
2. Disconnect ICC unit, and ABS actuator and electric unit (control unit) connectors, and connect them
securely again. Erase DTC, then perform self-diagnosis of ICC system again.
OK or NG
OK >> Poor connector connection. Check connector housing for disconnected, loose, bent and collapsed
terminals. If any malfunction is detected, repair as necessary. Erase DTC and perform ICC sys-
tem running test. Refer to ACS-9, "
ICC System Running Test" . Then perform self-diagnosis of
ICC system again.
NG >> GO TO 3.
98 GEAR POSITION×××

TCM malfunction

A/T turbine revolution sensor
malfunction

A/T vehicle speed sensor mal-
functionACS-49
102 LASER STAIN×× ×
ICC sensor body window has
contaminationACS-50
103 LASER SENSOR FAIL×× ×
ICC sensor internal malfunctionACS-51
104 LASER AIMING INCMP×× ×
Laser beam aiming of ICC sensor
is not adjustedACS-51
107 LASER COMM FAIL×× ×

CAN data received by ICC sen-
sor is strange (from ICC unit,
combination meter or ECM)ACS-51
109 LASER HIGH TEMP×× ×
Temperature around ICC sensor
is excessively highACS-52
DTC
No.CONSULT-II screen termsICC sys-
tem
warning
lampFail-safe
Malfunctions detected where...Refer-
ence
page Vehicle-
to-vehi-
cle dis-
tance
control
modeConven-
tional
(fixed
speed)
cruise
control
modeBrake
assist
(with pre-
view
function)

ACS-38
[ICC]
TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
Revision: October 20052005 QX56
3. CHECK HARNESS BETWEEN ICC UNIT AND ABS ACTUATOR AND ELECTRIC UNIT (CONTROL
UNIT)
1. Turn ignition switch OFF.
2. Disconnect ICC unit, and ABS actuator and electric unit (control
unit) connectors.
3. Check continuity between ICC unit harness connector B13 ter-
minal 10 (V/R), and ABS actuator and electric unit (control unit)
connector E125 terminal 7 (V/R).
OK or NG
OK >> Replace ICC unit. Refer to ACS-60, "ICC Unit" . Erase
DTC and perform ICC system running test. Refer to
ACS-9, "
ICC System Running Test" . Then perform self-diagnosis of ICC system again.
NG >>

Repair harness between ICC unit, and ABS actuator and electric unit (control unit).

Erase DTC and perform ICC system running test. Refer to ACS-9, "ICC System Running Test"
. Then perform self-diagnosis of ICC system again.
DTC 20 CAN COMM CIRCUITEKS00BM2
1. CHECK CAN COMMUNICATION
With CONSULT-II
1. Perform self-diagnosis.
2. Print self-diagnostic result.
>> After printing self-diagnostic result, GO TO “CAN system”. Refer to LAN-3, "
Precautions When
Using CONSULT-II" .
DTC 31 POWER SUPPLY CIR1, DTC 34 POWER SUPPLY CIR2EKS00BM3
1. CHECK ICC UNIT CONNECTOR
1. Turn ignition switch OFF.
2. Disconnect ICC unit connectors and connect them securely again. Erase DTC, then perform self-diagno-
sis of ICC system again.
OK or NG
OK >> GO TO 2.
NG >>

Poor connector connection.

Check connector. Check connector housing for disconnected, loose, bent, and collapsed termi-
nals. If any malfunction is detected, repair as as necessary. Erase DTC and perform ICC sys-
tem running test. Refer to ACS-9, "
ICC System Running Test" . Then perform self-diagnosis of
ICC system again.
2. CHECK POWER SUPPLY CIRCUIT FOR ICC UNIT
1. Turn ignition switch ON.
2. Check voltage between ICC unit harness connector B17 termi-
nal 33 (R/B), 42 (R/B) and ground.
OK or NG
OK >> GO TO 3.
NG >>

Repair ICC unit power supply harness.

Erase DTC and perform ICC system running test.
Refer to ACS-9, "
ICC System Running Test" . Then
perform self-diagnosis of ICC system again. Continuity should exist.
WKIA3616E
Battery voltage should exist.
SKIA11 73 E

TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
ACS-39
[ICC]
C
D
E
F
G
H
I
J
L
MA
B
ACS
Revision: October 20052005 QX56
3. CHECK GROUND CIRCUIT FOR ICC UNIT
1. Turn ignition switch OFF.
2. Disconnect ICC unit connectors.
3. Check continuity between ICC unit harness connector B13 ter-
minals 19 (B), 20 (B), and connector B17 terminal 46 (B) and
ground.
OK or NG
OK >> Replace ICC unit. Refer to ACS-60, "ICC Unit" . Erase
DTC and perform ICC system running test. Refer to
ACS-9, "
ICC System Running Test" . Then perform self-
diagnosis of ICC system again.
NG >>

Repair ICC unit ground harness.

Erase DTC and perform ICC system running test. Refer to ACS-9, "ICC System Running Test"
. Then perform self-diagnosis of ICC system again.
DTC 41 VHCL SPEED SE CIRCEKS00BM4
1. PERFORM ICC UNIT SELF-DIAGNOSIS
Perform self-diagnosis. Is “DTC 43 VDC/TCS/ABS CIRC” or “DTC 20 CAN COMM CIRCUIT” indicated in self-
diagnosis item display?
YES or NO
YES >> Repair or replace as necessary. Erase DTC and perform ICC system running test. Refer to ACS-
9, "ICC System Running Test" . Then perform self-diagnosis of ICC system again.
NO >> GO TO 2.
2. CHECK A/T VEHICLE SPEED SENSOR
With CONSULT-II
With data monitor, check “VHCL SPD AT”.
OK or NG
OK >> Replace ICC unit. Refer to ACS-60, "ICC Unit" . Erase DTC and perform ICC system running test.
Refer to ACS-9, "
ICC System Running Test" . Then perform self-diagnosis of ICC system again.
NG >>

Check TCM.

Erase DTC and perform ICC system running test. Refer to ACS-9, "ICC System Running Test"
. Then perform self-diagnosis of ICC system again.
DTC 43 VDC/TCS/ABS CIRCEKS00BM5
1. DIAGNOSIS CHECK 1
With CONSULT-II
Perform self-diagnosis. Is “CAN COMM CIRCUIT” indicated?
YES or NO
YES >> Repair or replace as necessary. Erase DTC and perform ICC system running test. Refer to ACS-
9, "ICC System Running Test" . Then perform self-diagnosis of ICC system again.
NO >> GO TO 2.Continuity should exist.
SKIA6650E

ACS-40
[ICC]
TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
Revision: October 20052005 QX56
2. DIAGNOSIS CHECK 2
With CONSULT-II
Perform self-diagnosis of ABS actuator and electric unit (control unit). Is malfunction indicated?
YES or NO
YES >> Repair or replace as necessary. Erase DTC and perform ICC system running test. Refer to ACS-
9, "ICC System Running Test" . Then perform self-diagnosis of ICC system again.
NO >> Replace ICC unit. Refer to ACS-60, "
ICC Unit" . Erase DTC and perform ICC system running test.
Refer to ACS-9, "
ICC System Running Test" . Then perform self-diagnosis of ICC system again.
DTC 45 BRAKE SW/STOP L SWEKS00BM6
1. CHECK CONNECTORS FOR ICC UNIT
1. Turn ignition switch OFF.
2. Disconnect ICC unit connectors and connect them securely again. Erase DTC, then perform self-diagno-
sis of ICC system again.
OK or NG
OK >>
Poor connector connection.

Check connectors. Check connectors housing for disconnected, loose, bent, and collapsed ter-
minals. If any malfunction is detected, repair as necessary. Erase DTC and perform ICC system
running test. Refer to ACS-9, "
ICC System Running Test" . Then perform self-diagnosis of ICC
system again.
NG >> GO TO 2.
2. CHECK STOP LAMP SWITCH AND ICC BRAKE SWITCH
With CONSULT-II
With data monitor, check if “STOP LAMP SW” and “BRAKE SW” are operating normally.
OK or NG
OK >> Replace ICC unit. Refer to ACS-60, "ICC Unit" . Erase DTC and perform ICC system running test.
Refer to ACS-9, "
ICC System Running Test" . Then perform self-diagnosis of ICC system again.
NG >>

BRAKE SW: GO TO 3.

STOP LAMP SW: GO TO 5.
3. ICC BRAKE SWITCH INSTALLATION AND ADJUSTMENT INSPECTION
Check ICC brake switch for proper installation and adjust if necessary. Refer to BR-6, "
BRAKE PEDAL" .
OK or NG
OK >> GO TO 4.
NG >> After adjustment, erase DTC and perform ICC system running test. Refer to ACS-9, "
ICC System
Running Test" . Then perform self-diagnosis of ICC system again.
4. CHECK ICC BRAKE SWITCH
Check ICC brake switch. Refer to ACS-59, "
ICC Brake Switch and Stop Lamp Switch" .
OK or NG
OK >> Replace ICC unit. Refer to ACS-60, "ICC Unit" . Erase DTC and perform ICC system running test.
Refer to ACS-9, "
ICC System Running Test" . Then perform self-diagnosis of ICC system again.
NG >> Replace ICC brake switch. Erase DTC and perform ICC system running test. Refer to ACS-9,
"ICC System Running Test" . Then perform self-diagnosis of ICC system again.

TROUBLE DIAGNOSIS FOR SELF-DIAGNOSTIC ITEMS
ACS-49
[ICC]
C
D
E
F
G
H
I
J
L
MA
B
ACS
Revision: October 20052005 QX56
2. CHECK NP RANGE SWITCH SIGNAL
With CONSULT-II
With data monitor, check that “NP RANGE SW” operates normally.
OK or NG
OK >> Perform TCM diagnosis. Refer to AT-85, "SELF-DIAGNOSTIC RESULT MODE" .
NG >> GO TO 3.
3. CHECK HARNESS BETWEEN ICC UNIT AND TCM
1. Turn ignition switch OFF.
2. Disconnect ICC unit harness connectors and A/T assembly har-
ness connector.
3. Check continuity between ICC unit harness connector B13 ter-
minal 7 (B/R) and A/T assembly harness connector F9 terminal
9 (B/R).
OK or NG
OK >> Replace ICC unit. Refer to ACS-60, "ICC Unit" . Erase
DTC and perform ICC system running test. Refer to
ACS-9, "
ICC System Running Test" . Then perform self-diagnosis of ICC system again.
NG >>

Repair harness between ICC unit and TCM.

Erase DTC and perform ICC system running test. Refer to ACS-9, "ICC System Running Test"
. Then perform self-diagnosis of ICC system again.
DTC 97 AT CIRCUITEKS00BMC
1. CHECK A/T CIRCUIT
With CONSULT-II
With TCM diagnosis, check that shift operates normally. Refer to AT-104, "
DTC P0705 PARK/NEUTRAL
POSITION SWITCH" .
OK or NG
OK >> Replace ICC unit. Refer to ACS-60, "ICC Unit" . Erase DTC and perform self-diagnosis of ICC
system again.
NG >>

Perform TCM diagnosis.

Erase DTC and perform self-diagnosis of ICC system again.
DTC 98 GEAR POSITIONEKS00BMD
1. DIAGNOSTIC CHECK
With CONSULT-II
Is “DTC 43 VDC/TCS/ABS CIRC” or “DTC 41 VHCL SPEED SE CIRC” indicated in self-diagnosis display
item?
YES or NO
YES >> Repair or replace as necessary. Erase DTC and perform self-diagnosis of ICC system again.
NO >> GO TO 2.
2. CHECK VEHICLE SPEED SIGNAL
With CONSULT-II
With data monitor, check that “VHCL SPEED SE” is normal.
OK or NG
OK >> GO TO 3.
NG >> Replace ICC unit. Refer to ACS-60, "
ICC Unit" . Erase DTC and perform self-diagnosis of ICC
system again.
7 - 9 Continuity should exist.
SKIA5982E

AT-34
A/T CONTROL SYSTEM
Revision: October 20052005 QX56
Lock-up Applied

In the lock-up applied state, the torque converter clutch control valve is set into the locked state by the
torque converter clutch solenoid and lock-up apply pressure is generated.
In this way, the torque converter clutch piston is pressed and coupled.
SMOOTH LOCK-UP CONTROL
When shifting from the lock-up released state to the lock-up applied state, the current output to the torque con-
verter clutch solenoid is controlled with the TCM. In this way, when shifting to the lock-up applied state, the
torque converter clutch is temporarily set to the half-clutched state to reduce the shock.
Half-clutched State

The current output from the TCM to the torque converter clutch solenoid is varied to gradually increase
the torque converter clutch solenoid pressure.
In this way, the lock-up apply pressure gradually rises and while the torque converter clutch piston is put
into half-clutched status, the torque converter clutch piston operating pressure is increased and the cou-
pling is completed smoothly.
Slip Lock-up Control

In the slip region, the torque converter clutch solenoid current is controlled with the TCM to put it into the
half-clutched state. This absorbs the engine torque fluctuation and lock-up operates from low speed.
This raises the fuel efficiency for 4th and 5th gears at both low speed and when the accelerator has a low
degree of opening.