NISSAN GT-R 1998 Repair Manual

TROUBLE DIAGNOSES
Circuit Diagram (Cont'd)
Data link connector for C0NS;ILT
Engine speed signal -
i? Throttle ~otal controi port&-2 s-2 33 7'' ELM I E - , 10
AT mode SW & '' 19
(2WD)
1- 1 I I Throttle msition sensor
I I Vehicle speed sensor 1
Turbine sensor 38 -
Throttle position SW 2 r I- 16
L TO IGN SW I PNPSW
To starter relay 4-1 34 - 27
A i 26
n I IGN IOA ID OFF 1ND.L AT> I T 22 I Shift CIU
ATN 1 987D

TROUBLE DIAGNOSES
Control Unit Input/Output Signal Specifications
Refer to EC section ("ECM.TCM or ECM Input/Output Signal
Reference Value").
USING CONSULT -
Monitor item Indication value Operating status
Throttle position sensor Approx.
0.4 - 4.OV
Throttle fully - closed to fully-open --
AK fluid temperature sensor I Appro~. 1.5 - 0.5V I A/T fluid: Appro~. 20 - 80°C -- - - --- -
ON Overdrive control switch: OFF
Lever switch
OFF Overdrive control switch: ON
Line pressure
duty 29 - 94% Low
pressure - High pressure
Lock-up duty
4 - 94% Lock-up released - Lock-up engaged
USING CIRCUIT TESTER
Terminal
No.' 1 Condition Specifications
.- Refer to EC section
("ECM-TCM or
5 (39) Engine speed signal - ECM Input/Output Signal Reference
Value*).
Voltage increases gradually in
Throttle position sensor
signal After
engine warm-up, depress accelerator pedal
slowly. response
to throttle position.
Fully-closed throttle
: Approx. 0.5V
Fully-open throttle : Approx. 4.2V
24 (I0) Power source
31 (19) Turn
ignition switch ON. Battery
voltage
Turn ignition switch OFF. Approx.
OV
--
25 (25) 1 Ground 32 (48) Turn ignition switch ON. Approx. OV
Shift control
signal SB1 - - 28 (I4) (Except RB20DE)
Vehicle speed sensor
2 When vehicle is moved at 2 to 3 km/h for more than Voltage varies approx. between OV 29 (40) (vehicle speed
signal in 1 m. and 4.5V intermittently.
speedometer)
*: Each number in parenthesis ( ) shows the terminal No. for TCM (RB25DE).

TROUBLE DIAGNOSES
Control Unit
InputlOutput Signal Specifications
Terminal
No.' Operation
or measurement condition Specifications
Idle switch
(in throttle position switch) After
engine warm-up, release accelerator pedal.
After engine warm-up, depress accelerator
pedal.
PNP switch "1"
position
(c > is used for M-AT.) Battery voltage
@ Approx.
OV
PNP switch
"2"
<"33 position
(c > is used for M-AT.) Selector lever:
"1"
&?"2 position
Selector lever;
Exce~t
"1"
<"2"> ~osition Battery voltage
gz
A~~rox.
OV
PNP switch
"Dm position Selector
lever:
2" <3*> position
Selector lever: Except
"Y 4'3'5 position
Selector lever;
"Dn
position Battery voltage
Approx. OV
Battery voltage
Neutral signal
(PNP switch
"N-P"
position)
- -- Selector lever: Except "Dm position Approx.
OV
PNP switch
"Rn
position RR Selector lever: "Nn, "P" position
Selector lever: Except
"N", "Pn position
Selector lever:
"Rn
~osition
I Selector lever: Except "Rn position 1 Approx. OV
U" " Approx. OV
Approx. 4.7V
. Batterv voltaae ST
I
After engine warm-up, depress accelerator pedal
partially. (Throttle opening: More than 50%) Battery voltage i% Full
switch
(in throttle position switch)
I After engine warm-up, release accelerator pedal. I Approx. OV
Sensor ground
Throttle position sensor
power -- -- - - - I
-- --- Turn iqnition switch ON. Ao~rox. OV @z!.
Shift control signal SB2
(Except RB20DE) Turn ignition switch
ON. Turn ignition switch
OFF.
Approx.
4.5 - 5.5V
Approx. OV
EL
Vehicle speed sensor 1
(Output shaft speed sensor) When vehicle
cruises at 30 kwh (Inspected in AC posi-
tion) More
than approx. 1 V
80
(Voltage increases in
resDonse to vehicle
meed.)
Turbine sensor (Except
RB20DE)
When vehicle parks (Inspected in AC position)
When turbine rotates at approx. 1,000
rpm I Approx. 0.1 V
Approx.
OV
rn fluid temperature sensor 5 I A/l fluid temperature: Approx. 20°C Approx. 1.5V
c
3 V) Battery voltage
Approx. OV .- Y .- c a, -
Afr mode switch (POWER)
(Except M-AT)
A/T fluid temperature: Approx. 80°C ,
AIT mode switch: POWER
A/T mode switch: Except POWER - - - - - - -- Shift control signal DB1
(Except RB20DE)
Shift control signal
DB3
(Except RB20DE) Approx. 0.5V
Overdrive control switch
(Except M-AT) Battery voltage
z g 0
Shift
control signal DB2
(Except RB20DE)
A/T mode switch (SNOW)
(Except TCS) Overdrive
control switch: ON (Contact: OFF)
- .= c .- & .&!
- 5
Stop lamp switch Overdrive
control switch:
OFF (Contact: ON)
CONSULT
(RX) signal Approx.
OV
Battery voltage Appro~. OV
Battery voltage
Approx. OV
.z w .- cJ=- T) .g
2
CONSULT (TX) signal
A/l mode switch: SNOW
A/l mode switch: Except SNOW
Depress brake pedal.
' Release brake pedal.
*: Each number in parenthesis ( ) shows the terminal No. for TCM (RB25DE).
AT-1 1

TROUBLE DIAGNOSES
Control Unit InputlOutput Signal Specifications
(Cont'd)
Terminal
No.' Operation
or measurement condition
Specifications
Total control signal
(multiple communication)
(Except
RB20DE) Refer to
EC section
("ECM.TCM or ECM Input1
Output Signal Reference Value").
I I
I Turn ignition swi?ch ON. I Battery voltage
Power supply (Backup)
Line pressure solenoid - - Turn ignition switch OFF. Battery voltage
r After engine
warm-up, depress accelerator pedal
Line pressure solenoid
(dropping resistor circuit) 5
Approx. OV
w
0.
s
Overrun clutch solenoid After engine
wan-up, release accelerator pedal.
After engine warm-up, release accelerator pedal.
After engine warm-up, depress accelerator pedal
fullv. .- >. .- 5
POWER indicator lamp (4AT)
Dual rnatic
AK waming lamp
(M-AT)
Approx. 1.5 - 3.OV
Approx. 4 - 14V
Approx. OV
When POWER indicator lamp is tumed on (W
mode switch: POWER), or dual matic warn-
ing lamp
is turned on
When
overrun clutch solenoid operates
When overrun clutch solenoid does not operate
Approx.
OV
Battery voltage Approx.
OV
When POWER indicator lamp is tumed off (NT
mode switch:Except POWER), or dual matic A/T Battery voltage
I warning lamp is turned off 1
I When vehicle is locked UD I Approx. 8 - 15V Lock-up solenoid I . .
When vehicle is not locked up I Approx. OV
When shift solenoid A operates
(Driving in 'Dln or
"D,")
When
shift solenoid A does not operate
(Driving in
"D," or "D,")
parenthesis
(
Battery voltage
Approx.
OV
Shift solenoid B
) shows the terminal No. for TCM (RB25DE ).
I
*: Each
When shift solenoid B operates
(Driving in 'Dln or
'D,")
When shift solenoid
B does not operate
(Driving in
"D,"
or
"Dd)
number Battery voltage
Approx. OV

TROUBLE DIAGNOSES
Shift Pattern
RB20DE ENGINE (4AX03 model)
"D" position normal mode (Overdrive control switch: ON)
Vehicle speed kmlh
"D" position POWER mode (Overdrive control switch: ON)
- - - --- --- Down-shift
Kickdown
area Vehicle speed
km/h
"D" position SNOW mode (Overdrive control switch: ON I -
I -
-
-
-
Vehicle speed km/h
AT-1 3
ATN 1 988D

TROUBLE DIAGNOSES
Shift Pattern (Cont'd)
RB25DE ENGINE (4AX01 model)
"D" position normal mode
Vehicle speed krnh "D" position SNOW mode
Kickdown area 3
------- Down-shift
10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180
Vehicle speed krnh
ATN 1 989C
RB25DET ENGINE (4AX00 model)
"D" ~osition normal mode
Vehicle speed kmfh

TROUBLE DIAGNOSES
Shift Schedule
VEHICLE SPEED WHEN SHIFTING GEARS
RB20DE engine (4AX03 model)
I 1 Vehicle meed km/h
Throttle opening
Full throttle
RB25DE engine (4AX01 model)
Shift pattern
Half throttle
I I Vehicle s~eed km/h
D14D2 I D2*D3 I D34D4 1 D4-1D3 I D3*D2 I D24D1
Normal
Power
Normal
Power
Full throttle 46 - 50
46
- 50
I
Throttle opening Shift pattern
31 - 35
43
- 47
I D2-rD3 I DJdD4 I D4*D3 1 D3*02 1 D24D1
91 - 99
91 - 99
Normal
Power
RB25DET engine (4AX00 model)
62 - 68
84
- 90 149
- 159
149
- 159
50
- 54
50
- 54 I
101 - 109
135
- 143
32
- 36
42
- 46 Half throttle
Throttle opening
VEHICLE SPEED WHEN PERFORMING LOCK-UP
144 - 154
144
- 154
101
- 109
101
- 109
Normal Power
Full throttle
Half throttle
71 - 79
83
- 91
61
- 67
85
- 91
Shift pattern
86 - 94
86
- 94
157
- 167
157
- 167
Vehicle speed krnlh
D14D2 I D2*D3 I D3*D4 I D4*D3 I D3*DZ I D2+D1
Normal
Power
Normal
Power
Closed throttle: Throttle opening
is 118 or below, and idle switch is turned OFF.
Half throttle: Throttle opening is 418.
41 - 45
41
- 45
41
- 45
45
- 51
104
- 112
135
- 143
Engine type
Model No.
speed
D4
speed
6-10
6- 10
151
- 161
151
- 161
-
45 - 49
45
- 49
31
- 35
39
- 43
RB20DE
4AX03
31
- 39
- D,
80 - 88
87
- 95
Lock-up OFF kmh
Lock-up
ON km/h
Lock-up
OFF kmlh
96 - 104
96
- 104
RB25DE
4AX01
34
- 42
- Lock-up ON km/h
40 - 44
40 - 44
37 - 43
45
- 51
-
103 - 111
103
- 111
74
- 80
84
- 90
RB25DET
4AX00
-
-
Closed throttle
Half throttle
Closed throttle
Half throttle
Closed throttle
Half throttle
Closed throttle
Half throttle
6-10
6-10
98
- 106
98 - 106
32
- 38
50
- 56
-- --
40 - 44
40
- 44
6-10
6- 10
167
- 177
167
- 177
111
- 119
133
- 141
23
- 31
101
- 109
44
- 52
120
- 128
35
- 43
110
- 118
-- -- -
161 - 171
161
- 171
63
- 71
98
- 106
25
- 33
104
- 112
48
- 56
118
- 126
38
- 46
107
- 115 59
- 67
121
- 129
55
- 63
128 - 136
52
- 60
103
- 111

TROUBLE DIAGNOSES
n t
\-Test port for "D", "2", and "1" positions
I 'Test port for "I?" position I
Line pressure specification
Basic Inspection
Arr FLUlD
Check A/T fluid for leakage and fluid level.
Check A/T fluid status.
SHIFT CONTROL
Check and adjust A/T position.
Line Pressure Test
1. Check engine oil level. If necessary, add oil.
2. Drive vehicle for approximately 10 minutes until A/T fluid
reaches normal operating temperature between
50 and 80°C,
and check A/T fluid level. If necessary, add fluid.
When
ambient temperature is 20°C, A/T fluid operating tem-
perature
usually becomes between 50 and 80°C for approxi-
mately
10 minutes' drive in urban traffic.
3. After warming up IW', remove fluid pressure detection plug,
and install pressure gauge (Special Service Tool:
ST2505
S001) to corresponding line pressure port.
CAUTION:
0 To remove or install the fluid pressure detection plug, use
standard socket wrench (width across flat:
12 mm).
Detection plug should not be reused because thread-lock
compound is applied
to the plug.
4. Set parking brake and block wheels.
5. Start engine and measure line pressure at idle and stall speed.
CAUTION:
When measuring line pressure, depress brake pedal fully.
When measuring line pressure at stall speed, refer to
"Stall Test" (AT-17).
I p- Line pressure MPa (kg/crn2)
Engine speed
I "RW position "On, 'Z", "1" positions (4AT)
"Dm,
"3", "2" positions (M-AT)
At idle speed
At stall speed 0.58 - 0.62 (5.9 - 6.3) 0.47 - 0.51 (4.8 - 5.2)
1.71
- 1.78 (1 7.4 - 18.2) 1.22 - 1.29 (1 2.4 - 13.2)

TROUBLE DIAGNOSES
Line Pressure Test (Cont'd)
JUDGEMENT OF LINE PRESSURE TEST
At idle
speed
At stall
speed Judgement
Line pressure is low in all
positions.
Line pressure is low in par-
ticular position.
Line pressure is
high.
Line pressure increase is
poorer than that measured at
idle speed.
Line pressure increases but
does not reach specification.
Line pressure is low in par-
ticular position. Possible
causes
Pressure supply system malfunction or low oil pump output
Examples:
0 Oil pump wear
Control piston damage
Pressure regulator valve or plug sticking, and weak spring
Fluid pressure leakage between oil strainer and pressure regulator valve through oil Eg
Pump
Low idle speed
After line pressure is supplied from manual valve, fluid pressure may leak between devices
or circuits of corresponding position.
1
Malfunctions of sensors or pressure regulation function. El
Examples:
Misadjustment of throttle position sensor
PJT fluid temperature sensor damaged ST
Poor operation of line pressure solenoid (stuck with OFF status, clogged filter, or open
harness)
Pressure modifier valve sticking F%
Pressure regulator valve or plug sticking
Malfunctions of sensors or pressure regulation function
Examples:
EILA
Misadjustment of throttle position sensor
TCM, ECM.TCM damaged la
Poor operation of line pressure solenoid (stuck or shorted with ON status)
Pressure regulator valve and plug sticking
Pressure modifier valve sticking
sf$
Pilot valve sticking and pilot filter clogged
Malfunctions of pressure supply system, sensors, or pressure regulation function
Examples:
Misadjustment of throttle position sensor
Control piston damage
Poor operation of line pressure solenoid, and filter sticking or clogged
Pressure regulator valve and plug sticking
Pressure modifier valve sticking
Pilot valve sticking and pilot filter clogged
After line pressure is supplied from manual valve, fluid pressure
may leak between devices
or circuits of corresponding position.
Stall Test
1. Check engine oil level. If necessary, add oil.
2. Drive vehicle for approximately 10 minutes until A/T fluid
reaches normal operating temperature between
50 and 80°C,
and check A/T fluid level. If necessary, add AfT fluid.
When ambient temperature is
20°C,
A/T fluid operating tem-
perature usually becomes between 50 and
80°C for approxi-
mately
10 minutes' drive in urban traffic.
3. Set parking brake and block wheels.
4. Statt engine, depress brake pedal, and move selector lever to
"D" position.

TROUBLE DIAGNOSES
Stall Test (Cont'd)
JUDGEMENT OF STALL SPEED
5. Depress accelerator pedal gradually while depressing brake
pedal.
6. Read stall speed quickly, and immediately release accelerator
pedal.
CAUTION: Do not
depress accelerator pedal for more than 5 seconds
when testing.
7. Move selector lever to "N" position.
8. Cool down fluid.
CAUTION:
Run engine at idle
for at least one minute.
Specification:
RB20DE 2,300 - 2,500 rpm
RB25DE 2,350 - 2,550 rpm
RB25DET 2,920 - 3,170 rpm
7 Lever position
Stall
speed status Possible causes
Forward
clutch
Forward one-way clutch
Low one-way clutch
Engine and torque converter one-way clutch
7-
0
Line pressure circuit (line pressure drop), forward clutch, low one-way clutch
and forward one-way clutch
Line pressure circuit (line pressure drop), reverse clutch and forward clutch
Forward clutch, low one-way clutch, forward one-way clutch, reverse clutch
and forward clutch
Line pressure circuit (line pressure drop), forward clutch, low one-way clutch,
forward one-way clutch, reverse clutch and
forward clutch
Clutches and brake are normal except high clutch, brake band, and overrun
It
I
0
0 0 Low & reverse brake
Reverse clutch
0: Within stall speed specification
H: Higher than stall speed specification
L: Lower than stall speed specification
0 0 0 clutch. (However, status of high clutch, brake band, and overrun clutch cannc
be confirmed by stall test.)