1998 NISSAN GT-R engine

ENGINE AND EMISSION CONTROL OVERALL SYSTEM
ECM (-TCM) Terminal Layout (Cont'd)
Terminal
No.
67
'68
69 Description
70
'71
72 I
Control unit power supply
O/D OFF indicator
lamp
DB (data bush) 2 signal
[RB25DET.AIT]
73
101
104
1 [RB~ODE (LIB), BR25DEl -
Turbo oressure control solenoid valve control signal I I16 I lnjector ground
Terminal
No.
AK mode switch signal (SNOW) [RB20DE (UB).AIT]
Stop lamp switch signal
Control unit power
102
103 Description
74
75 (RX)
76
(TX)
1 I . .
-
Receive (Data input to control unit)
Transmit (Data output from control unit)
77
78
79
-
Injector No. 3 cylinder drive signal
Variable air intake control solenoid valve control
sianal
105
'106
107
-
Auxiliary electric fan relay control signal [RB25DE, RB25DElJ
ECM.TCM. TCSIABS integrated control signal [Multiplex
com-
munication] [RB25DENT. RB25DEl
Battery power supply
Line pressure solenoid valve control signal (Dropping resistor
circuit)
-
lnjector No. 1 cylinder drive signal
1 08
log
80
"I3
114
'1 15
[RB~~DET]
Injector No. 2 cylinder drive signal
Line pressure solenoid valve control signal
Air jet swirl control solenoid valve control signal
[RB20DE
(U ,\I
110 111
112 Injector No.
4 cylinder
drive signal
Overrun clutch solenoid valve control signal
"11
Canister purge control valve control signal
Control unit power supply (Counter-electromotive current
feedback
circuit) 11
7
118
.119
Symbols
in ( ) next to terminal numbers indicate the data link connector terminals. Items marked with ' are available on RB20DE (UB) and R825DET.All models only.
Injector No. 5 cylinder drive signal
Fuel pump terminal voltage control output signal
[RB25DET]
Injector No. 6 cylinder drive signal Variable
timing control solenoid valve control signal
Heated oxygen sensor heater control signal
Power indicator lamp
'120
'121 Lockup solenoid valve control signal
Shift solenoid valve
A control signal I '122
123 124 Shift solenoid valve B control signal
-
Injector ground

TROUBLE DIAGNOSES --- - - - -- -- - -
Fail-safe and Backup Functions
0 The fail-safe function estimates the opening conditions with other input signals and selects safer condi-
tions for the engine (vehicle) control, based on the data previously stored in the control unit, when any of
the critical sensors in the
ECM fails.
The backup function allows the vehicle to be driven, using control signals previously stored in the control G]
unit, even if the critical part of the system fails.
MIL indication
I
Related
sensor
Function
Backup Malfunction
Fail-safehacku p
Fixes the ignition timing, fuel injection pulse width, and
AAC valve opening to the preset values so that the vehicle
can be driven.
ECM
(-TCM)
Mass air
flow
sensor
Engine
coolant
tempera- ture sen-
sor The
microcomputer in the control
unit (CPU) is malfunctioning. MIL lights
up. A'
-- --
Selects the fuel injection pulse width according to the
engine speed and the throttle opening so that the vehicle
can be driven. Fuel injection will be inhibited when the
engine speed exceeded approx.
2,400 rpm. During fail-safe
control, idle speed is controlled to 800
rpm.
Uses the estimated engine coolant temperature (varies with
elapsed time after start) to perform controls so that the
vehicle can be driven normally. The auxiliary electric fan
relay is turned ON. On
RB25DET
model, the turbo pres-
sure control solenoid valve remains OFF.
%R
MIL lights up.
ST
Output voltage dropped below
0.3V while the engine is running.
MIL lights up.
R8 Same as self-diagnostic malfunc-
tion detection conditions.
Heated
owen
sensor Heated oxygen sensor output
voltage exceeded approx.
2V for
predetermined time.
Same as self-diagnostic malfunc-
tion detection conditions. MIL
lights up. d d Inhibits aidfuel ratio feedback control.
Judges the vehicle as of regular specification. Retards the
ignition timing within the knocking range so that the vehicle
can be driven normally.
Determines idle position according to the throttle position
and the engine speed.
Fixes the output to the preset value so that the vehicle can
be driven normally.
On
RB25DET model, the turbo pressure control solenoid
valve remains OFF.
Fail-safe
function Knock
sensor
Throttle position
sensor Same
as self-diagnostic malfunc-
tion detection conditions. MIL
lights up.
Throttle motor
sensor
--
Fixes the throttle motor sensor output to the preset value
by turning the TCS switch
ONIOFF, so that the vehicle can
Same
as self-diagnostic malfunc-
tion detection conditions. MIL
lights up.
be driven normally.
Motor
throttle
switch Same
as
self-diag
nostic
malfunc-
tion detection conditions. Fixes the
TCS switch OFF.
t.. -

Self-diagnosis
DESCRIPTION
In self-diagnosis, when any of the critical sensors in the engine control system fails and the self-diagnos-
tic malfunction detection conditions are satisfied, the malfunctioning system is stored in the control unit for
easier trouble diagnosis.
There are two methods to indicate the presence of a malfunction: By illuminating the malfunction indica-
tor lamp (MIL) on the combination meter or by displaying on the CONSULT screen. Here describes indi-
cation by the malfunction indicator lamp.
There are two types of diagnostic test modes: Mode I and Mode 11. Mode I is normal status. Mode I1 is
either SELF-DIAGNOSTIC RESULT or
HEATED OXYGEN SENSOR MONITOR function.
SELF-DIAGNOSIS OPERATION PROCEDURE
To activate Diagnostic Test Mode I1 self-diagnosis, with the ignition witch turned ON (engine not running),
connect terminals CHK and IGN on the data link connector for
2 or more seconds with a suitable harness,
then disconnect them.
Perform self-diagnosis with the ignition switch remain in ON position. [Mode I1 SELF-DIAGNOSTIC
RESULTS]
When engine is started in the above status, the heated oxygen sensor monitor function will be activated.
[Mode
II HEATED OXYGEN SENSOR MONITOR]
When ignition switch is turned off during diagnosis, the diagnosis will automatically returns to Diagnostic
Test Mode
I. [Normal status]
I 1 r I, rest Mode I - I I I r II MAL~UNLMNI WARNlNfi +
Switching diagnostic test modes
n
Connect terminals "CHIC and 'IGN'
on the data link connector for CON-
SULT for
2 or more seconds w~th a
suitable harness, then disconnect
them.
Diagnostic Test Mode
II
- SELF-DI- Diagnostic
Test Mode I1 - HEATED AGNOSTIC RESULTS OXYGEN SENSOR MONITOR
MIL indication (Blinkmg) MIL indicabon (Blinking)
When normal: MIL blinks to indicate Indicates
lean (ON) and rich
(OFF).
'DTC 55'. When malfunction detected: MIL
blinks to indicate DTC of
malfunction-
11 ing systern(s). I I
Erasing self-diagnostic results
Connect Leyinals
'CHIC and 'IGN"
on
the
data
hnk
connector for CON-
SULT for
2 or more seconds with a
suitable harness. then
dsconnect
them.
CAUTION: When ignition switch is turned ON within sev-
eral seconds after it is
turned OFF wh~le Diag-
nostic Test Mode II - SELF-DIAGNOSTIC
RESULTSIHEATEO
OXYGEN SENSOR MONI-
TOR
is activated, SELF-DIAGNOSTIC RESULTS will be performed again.

TROUBLE DIAGNOSES
Self-diagnosis (Cont'd)
I Malfunction indicator lamp
MALFUNCTiON INDICATOR LAMP (MIL) INDICATION
Diagnostic test mode I - BULB CHECK
0 The malfunction indicator lamp bulb check is carried out when
the ignition switch is turned
ON (engine not started).
The malfunction indicator lamp should come ON when the
ignition switch is turned
ON, and go OFF when the engine is
started.
Example: Blinking pattern for DTC "43"
ONh
OFF
Approx. 8.7 S
OFF (Rich)
Duty ratio in 1 cycle 1 Lean: Al(A + B) x 100 Rich: B/(A + B) x 100
EFJ0041 C
Diagnostic test mode I - MALFUNCTION WARNING
The system goes into the malfunction warning mode when any of
the following conditions is satisfied, and warns the driver by light-
ing up the malfunction indicator lamp in the combination meter.
Microcomputer in the ECM control unit (CPU) is malfunction-
1
ing.
Malfunction is detected during mass airflow sensor circuit self-
diagnosis.
Malfunction is detected during engine coolant temperature
sensor circuit self-diagnosis.
Malfunction is detected during vehicle speed sensor circuit
self-diagnosis.
Malfunction is detected during ignition signal circuit
self-diag-
nosis.
Malfunction is detected during overheat self-diagnosis.
Malfunction is detected during heated oxygen sensor circuit
self-diagnosis.
~alfunsion is detected during throttle position sensor circuit
self-diagnosis.
Malfunction is detected during Turbo pressure sensor circuit
self-diagnosis.
[RB25DET model]
Malfunction is detected during throttle motor sensor circuit self-
diagnosis.
[RB25DET model]
Diagnostic test mode I1 - SELF-DIAGNOSTIC RESULTS
0 This mode indicates the malfunctioning system(s) by the mal-
function indicator lamp blinking pattern (indicating the DTC).
0 When no malfunction is detected, DTC "55" is indicated.
Diagnostic test mode II - HEATED OXYGEN SENSOR
MONITOR
0 This mode indicates status of the aidfuel ratio by blinks of the
malfunction indicator lamp.
Warm up the engine and increase and maintain the engine
speed at 2,000 rpm. Check that the malfunction indicator lamp
blinks at least five times in
10 seconds.
During airlfuel ratio feedback control,
when heated oxygen sensor output is high (rich): MIL goes
OFF.
when heated oxygen sensor output is low (lean):
MIL comes
ON.
When aidfuel ratio feedback control is clamped: Status just
before clamp
is maintained.
When airifuel ratio feedback control is stopped: MIL goes OFF.

TROUBLE DIAGNOSES
Self-diagnosis
(Cont'd)
SELF-DIAGNOSTIC INDICATION ITEMS
I time while the engine is running. I
MIL indication
-
DTC No.
,,
MIL lights up. l2
Self-diagnostic test items
Crankshaft position sen-
sor signal circuit Malfunction (DTC No.)
indication conditions (Malfunction is detected when ...)
lo (POS) signal or 120" (REF) signal is not input for predetermined time
while the engine is running.
Abnohal correlation is detected between 1" (POS) signal and 120" (REF)
sianal.
Mass air flow sensor
signal circuit
MIL lights up.
Engine coo'ant tempera-
"
Mass air flow sensor output voltage is 4.9V or greater for predetermined
time when ignition switch is turned from OFF to ON, or after the engine is
stalled.
Mass air flow sensor output voltage is less than 0.3V for predetermined
Engine coolant temperature sensor output voltage is approx.
4.8V or
greater (open circuit) or less than
0.06V (short circuit) for predetermined
MIL lights up.
-
14
ABS-TCS control unit
circuit JRB25DEl-l
ture sensor signal circuit Throttle control unit detects malfunction
in the system. (Open throttle sen- sor harness, etc.)
Ignition signal circuit
Turbo pressure sensor
signal circuit
[RB25DET]
Overheat
I 1 mined time. I
time-
Vehicle speed sensor
signal circuit
Motor throttle switch sig-
nal circuit
[RB25DET]
TCS/ABS control unit detects malfunction. 1 -
I Knock sensor signal cir-
cuit
- --
No vehicle speed signal is input for predetermined time while the vehicle is
being driven after warm up.
Abnormal correlation is detected between input voltages from the throttle
motor sensor and from the motor throttle switch for predetermined time.
I
MIL lights up. Heated oxygen sensor
signal circuit
Throttle position sensor
signal circuit
No consecutive ignition signal while the engine is running.
Turbo pressure sensor output voltage is approx. 4.8V or greater (open cir-
cuit) or less than
0.06V (short circuit) for predetermined time.
Engine coolant temperature sensor output voltage is approx. 0.35V or less
(sensor normal) for predetermined time.
a Heated oxygen sensor output voltage is approx. 0.2V or greater and less
than approx.
0.4V for predetermined time while the vehicle is being driven
aner warm up. Heated oxygen sensor output voltage is approx. 2V or greater for predeter-
ABS-TCS communica- tion circuit
[RB25DET]
Throttle motor sensor
signal circuit
[RB25DET]
Afr communication cir-
cuit
MIL lights up.
lights
up.
MIL lights up.
NQ malfunction
I a At least one knock sensor indicates the output voltage of approx. 4V or
greater (open circuit) or less than approx.
1V (short circuit).
Throttle position sensor output voltage is approx. 4.7V or greater (open cir-
cuit) or less than
0.06V
(short circuit) for predetermined time while ark/
a Throttle motor sensor input voltage is approx. 418~or greater (open circuit) MIL lights up.
or less than
0.3V
(short circuit) for predetermined time. I
-
MIL liqhts up. neutral position switch is OFF and vehicle speed is 4 kdh or higher.
a Malfunction (openlshort circuit, etc.) is detected in multiplex communication
line between enaine and
TCWABS.
Malfunction is detected in PA communication circuit in ECM (-TCM).
[RBZODE (UB), RB25Dm a Malfunction (open circuit, short circuit, etc.) is detected in multiplex commu-
nication line between ECM and TCM.
[RB25DE1
-
-
No malfunction is detected in all the above circuits. I - - --
Some of the above ~elfaia~nostic test items can cause related malfunctions to be detected in M,
throttle control, and ABS seif-diagnosis when malfunction is detected. Therefore, malfunctions should
also be checked in self-diagnostic tests for systems other than engine.
CONDITIONS TO TURN OFF MALFUNCTION INDICATOR LAMP
Vehicle speed sensor signal circuit: Correct the sensor signal, then drive the vehicle at 4 km/h or higher.
Overheat: Check
for causes of overheat, then erase self-diagnostic results.
Other items: Malfunction indicator lamp turns
OFF when the vehicle returned to normal condition.
HOW TO ERASE SELF-DIAGNOSTIC RESULTS
In Diagnostic Test Mode II, with the engine stopped (ignition switch ON), connect terminals "CHK" and "IGFP
on the data link connector for
2 or more seconds with a suitable harness, then disconnect them.

TROUBLE DIAGNOSES
NISSAN
CONSULT
START
I 1
I SUB MODE BR455C
1 b SELECTeYSTEM
[ ENGINE
I
b SELECTDIAG MODE n]
WORK SUPPORT
SELF-DIAG
RESULTS
DATA MONITOR
ACTIVE TEST
FUNCTION TEST
, ECM PART NUMBER
SEF288S
CONSULT
CONSULT INSPECTION PROCEDURE
Turn ignition switch OFF.
Connect "CONSULT to data link connector for CONSULT.
(Data link connector for CONSULT is located under the instru-
ment lower cover on the driver's side on both LHD and
RHD
models.)
I
Turn ignition switch ON.
Touch "START'.
Touch "ENGINE".
Perform each diagnostic test mode according to each service
procedure.
For further information, see the CONSULT Operation Manual.

TROUBLE DIAGNOSES
CONSULT (Cont'd)
FUNCTION
Self-diagnostic results Diagnostic test mode
Work support
Self-diagnostic resuits can
be read and
erased quickly. Function
A technician can adjust some devices faster
and more accurately by following indications
on CONSULT.
Data monitor
Active test
WORK SUPPORT MODE
Input/Output data in the ECM can be read.
CONSULT drives some actuators apart from
the
ECM's and
also shifts some parameters in
a specified range.
Conducted
by CONSULT instead of a techni-
Function test
ECM part number
WORK ITEM I CONDITION I USAGE
cian to determine whether each system is
"OK" or
"NG".
ECM part number can be read.
THRTL
POS SEN ADJ CHECK THE THROTTLE POSITION SENSOR SIGNAL.
ADJUST IT TO THE SPECIFIED VALUE
BY ROTATING
THE SENSOR BODY UNDER THE FOLLOWING CONDI-
TIONS.
0 IGN SW "ONn
0 ENG NOT RUNNING When adjusting
throttle position
sensor initial position
I ACC PEDAL NOT PRESSED 1 I
IACV-AAC VALVE ADJ I SET ENGINE SPEED AT THE SPECIFIED VALUE UNDER I 1 THE FOLLOWING CONDITIONS.
ENGINE WARMED UP
When releasing fuel pressure I
from fuel line
FUEL
PRESSURE RELEASE
0 NO-LOAD
FUEL PUMP WILL STOP BY TOUCHING "START"
DURING IDLING.
CRANK A FEW TIMES AFTER ENGINE STALLS.
i J

TROUBLE DIAGNOSES m
CONSULT (Cont'd)
SELF-DIAGNOSTIC RESULTS MODE
When any of the control unit input/output signal circuits fails and the self-diagnostic malfunction detection
conditions
are satisfied, the malfunctioning circuit is stored in the memory and displayed later.
Self-diagnostic test items I Malfunction is detected when ... Data storage
Malfunction display item I (Yes/No,
Crankshaft position sen-
sor signal circuit
I predetermined time while the engine is running. 1 1 mm
Mass air 'low sensor sig- nal circuit
1" (POS) signal or 120" (REF) signal is not input for pre-
determined time while the engine is running.
Abnormal correlation is detected between 1" (POS) sig-
nal and 120" (REF) signal.
Mass air flow sensor output voltage is 4.9V or greater for
Vehicle speed sensor sig-
No vehicle speed signal is input for predetermined time Vehicle speed sensor I I Yes ST nal
circuit I while the vehicle is beina driven after warm UD.
predetermined time when ignition switch is turned from
OFF to ON, or after the engine is stalled.
Mass air flow sensor output voltage is less than 0.3V for
Engine coolant tempera-
ture sensor signal circuit
Crankshaft position sen-
sor
Mass air flow sensor
AT
Yes RS
-.
yes I
Engine coolant temperature sensor output voltage is
approx. 4.8V or greater (open circuit) or less than 0.06V
(short circuit) for predetermined time.
switch sig- nal circuit JRB25DETI
Engine coolant tempera- ture sensor
Abnormal correlation is detected between input voltages
from the throttle motor sensor and from the motor
throttle switch for predetermined time.
ABS-TCS control unit cir- cuit [RB25DETJ
19 L~J
Yes
--
Motor throttle switch
lgnition signal circuit
Turbo pressure sensor
signal circuit [RB25DETl
Overheat
Yes
Throttle control unit detects malfunction in the system.
(Open throttle sensor harness, etc.)
TCS/ABS control unit detects malfunction.
Heated oxygen sensor signal circuit ABS-TCS
C/U SIGNAL
No consecutive ignition
signal while the engine is run-
ning.
Turbo pressure sensor output voltage is approx. 4.8V or
greater (open circuit) or less than
0.06V (short circuit) for
predetermined time.
Engine coolant temperature sensor output voltage is
approx.
0.35V or less (sensor normal) for predetermined
time.
Yes
Heated oxygen sensor output voltage is approx. 0.2V or
greater and less than approx.
0.4V for predetermined
time while the vehicle is being driven after warm up.
Heated oxygen sensor output voltage is approx. 2V or
greater for medetermined time.
Knock cuit lgnition
switch (Start sig-
nal)
TURBO PRESS SENSOR
OVER HEAT
Oxygen sensor
Yes Yes
EL
Yes
8D
Yes
At
least one knock sensor indicates the output voltage of
approx. 4V or greater (open circuit) or less than approx.
1 V (short circuit).
Throttle position sensor
signal circuit
ABS-TCS communication
Malfunction (openlshort circuit, etc.) is detected in multi- ABSrrCS C,u circuit [RB25DETl 1 plex communication line between enaine and TCS/ABS. I
Knock sensor
Throttle position sensor output voltage is approx. 4.7V or
greater (open circuit) or
0.06V or less (short circuit) for
predetermined time while
parkheutral position switch is
OFF and vehicle
s~eed is 4
km/h or hiaher. Thronle
position sensor
Throttle motor sensor sig- nal circuit
[RB25DET] Yes
AiT communication
circuit
Yes
Throttle motor sensor input voltage is approx. 4.8V or
greater (open circuit) or less than
0.3V or less (short cir-
cuitl for
redetermined time.
No malfunction Motor
throttle sensor
Malfunction is detected in A/T communication circuit in
ECM
(.TCM).
(RB2ODE
(UB), RB25DET]
a Malfunction (opedshort circuit, etc.) is detected in multi-
plex communication line between ECM and TCM.
[RB25DE1
No malfunction is detected in all the above circuits.
A/T COMM LINE
NO SELF DIAGNOSTIC
FAILURE INDICATED.
FURTHER TESTING MAY
BE REQUIRED.
Some of the above self-diagnostic test items can cause related malfunctions to be detected in An;
throttle control, and ABS self-diagnosis when malfunction is detected. Therefore, malfunctions should
also
be checked in self-diagnostic tests for systems other than engine.