
ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-9
On-Board Diagnostic System (Vehicle with
Monitor Connector)
ECM diagnosis troubles which may occur in the area including the
following parts when the ignition switch is ON and the engine is
running, and indicates the result by turning on of flashing mal-
function indicator lamp (1).
• Heated oxygen sensor (if equipped)
•ECT sensor
•TP sensor
• IAT sensor
• CMP sensor
•MAF sensor
• Knock sensor
• EGR (if equipped)
•VSS
• CPU (Central Processing Unit) of ECM
ECM and malfunction indicator lamp (1) operate as follows.
• Malfunction indicator lamp (1) light when the ignition switch
is turned ON (but the engine at stop) with the diagnosis
switch terminal ungrounded regardless of the condition of
Engine and Emission control system. This is only to check
the malfunction indicator lamp (1) bulb and its circuit.
• If the above areas of Engine and Emission control system is
free from any trouble after the engine start (while engine is
running), malfunction indicator lamp (1) turns OFF.
• When ECM detects a trouble which has occurred in the
above areas, it makes malfunction indicator lamp (1) turn ON
while the engine is running to warn the driver of such occur-
rence of trouble and at the same time it stores the trouble
area in ECM back-up memory. (The memory is kept as it is
even if the trouble was only temporary and disappeared
immediately. And it is not erased unless the power to ECM is
shut off for specified time.)
ECM also indicates trouble area in memory by means of
flashing of malfunction indicator lamp (1) at the time of
inspection. (i.e. when diagnosis switch terminal (2) is con-
nected to ground terminal (3) with a service wire and ignition
switch is turned ON.)
NOTE:
When a trouble occurs in the above areas and disappears
soon while the diagnosis switch terminal is ungrounded
and the engine is running, malfunction indicator lamp (1)
lights and remains ON as the trouble exists but it turns
OFF when the normal condition is restored.

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-21
For A/T system (Refer to Section 7B1 for diagnosis)
P0505Idle air control system mal-
functionDifference between desired idle speed
and actual idle speed continues to
exceed specified value for longer than
specified time.2 driving
cyclesNot
applicable
P0601
(No.71)Internal control module mem-
ory check sum errorData write error (or check sum error)
when written into ECM1 driving
cycle1 driving
cycle
P1408Manifold absolute pressure
sensor circuit malfunctionManifold absolute pressure sensor
output voltage is higher or lower than
specified value (or sensor circuit
shorted to ground or open).2 driving
cyclesNot
applicable
P1450Barometric pressure sensor
circuit malfunctionBarometric pressure is lower or higher
than specification.1 driving
cycleNot
applicable
P1451Barometric pressure sensor
performance problemDifference between intake manifold
pressure and barometric pressure is
larger than specification.2 driving
cyclesNot
applicable
P1500Engine starter signal circuit
malfunctionEngine starts with no starter signal or
signal input during long period after
start.2 driving
cyclesNot
applicable
P1510ECM back-up power supply
malfunctionNo back-up power after starting
engine.1 driving
cycleNot
applicable DTC NO. DETECTED ITEMDETECTING CONDITION
(DTC will set when detecting : )MIL
(vehicle
without
monitor
connector)MIL
(vehicle
with
monitor
connector)
DTC NO. DETECTED ITEMDETECTING CONDITION
(DTC will set when detecting : )MIL
(vehicle
without
monitor
connector)MIL
(vehicle
with
monitor
connector)
P0705
(No.72)Transmission range switch cir-
cuit malfunctionMultiple signals inputted simulta-
neously or P, R, N, D, 2 or L range sig-
nal not inputted while running at
60km/h or more.2 driving
cyclesNot
applicable
P0715
(No.76)Input speed sensor circuit
malfunctionInput speed sensor signal is lower
than specification while running.2 driving
cyclesNot
applicable
P0720
(No.75)Output speed sensor circuit
malfunctionOutput speed sensor signal not input-
ted while VSS signal being inputted.2 driving
cyclesNot
applicable
P0741TCC (lock-up) solenoid perfor-
mance or stuck offActual TCC operation does not agree
with ON/OFF control from PCM to
TCC.2 driving
cyclesNot
applicable
P0743
(No.65)
(No.66)TCC (lock-up) solenoid electri-
calMonitor signal OFF is detected when
TCC control solenoid is ON or monitor
signal ON is detected when it is OFF.1 driving
cycleNot
applicable
P0751Shift solenoid A (#1) perfor-
mance or stuck offGear change control from PCM to A/T
does not agree with actual gear posi-
tion of A/T.2 driving
cyclesNot
applicable

6-1-22 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
For immobilizer control system (Refer to Section 8G for diagnosis)
P0753
(No.61)
(No.62)Shift solenoid A (#1) electricalMonitor signal OFF is detected when
shift solenoid A (#1) is ON or monitor
signal ON is detected when it is OFF.1 driving
cycleNot
applicable
P0756Shift solenoid B (#2) perfor-
mance or stuck offGear change control from PCM to A/T
does not agree with actual gear posi-
tion of A/T.2 driving
cyclesNot
applicable
P0758
(No.63)
(No.64)Shift solenoid B (#2) electricalMonitor signal OFF is detected when
shift solenoid B (#2) is ON or monitor
signal ON is detected when it is OFF.1 driving
cycleNot
applicable
P18754WD low switch circuit mal-
functionDifference between vehicle speed
detected by VSS and vehicle speed
detected by output speed sensor and
compensated by 4WD low switch is
larger than specification.2 driving
cyclesNot
applicable DTC NO. DETECTED ITEMDETECTING CONDITION
(DTC will set when detecting : )MIL
(vehicle
without
monitor
connector)MIL
(vehicle
with
monitor
connector)
DTC NO. DETECTED ITEMDETECTING CONDITION
(DTC will set when detecting : )MIL
(vehicle
without
monitor
connector)MIL
(vehicle
with
monitor
connector)
P1620
(No.84)ECU code not registered
Refer to Section 8G P1621
(No.83)NO ECU code transmitted
from Immobilizer Control Mod-
ule
P1622
(No.82)Fault ECM
P1623
(No.81)ECU code not matched
NOTE:
DTC NO. with (*) is detected only vehicle without monitor connector.
DTC No. with (**) is detected only vehicle with monitor connector.
For ( ) marked No. in DTC column, it is used for vehicle with monitor connector.
DTC No.12 appears when none of the other codes is identified.

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-23
Fail-Safe Table
When any of the following DTCs is detected, ECM (PCM) enters fail-safe mode as long as malfunction continues
to exist but that mode is canceled when ECM (PCM) detects normal condition after that.
DTC NO. TROUBLE AREA FAIL SAFE OPERATION
P0100
(No.33, 34)MAF SENSOR• Injector drive time (fuel injection volume) is determined according to
throttle valve opening and engine speed.
• EGR valve stops.
• Air flow of IAC valve is limited.
P0110
(No.23, 25)IAT SENSOR Each control is performed on the basis of 22.1°C intake air temp.
P0115
(No.14, 15)ECT SENSOR• Each control except 4-A/T is performed on the basis of 29.9°C engine
coolant temp.
• 4-A/T control is performed assuming 31°C (engine warmed up) or
higher after 15 min. from engine start.
P0120
(No.21, 22)TP SENSOR• Each control except 4-A/T is performed on the basis of 124.5° throttle
valve opening.
• 4-A/T control is performed on the basis of 0° throttle valve opening.
P0460 FUEL LEVEL SENSOR Each control is performed in the basis of full fuel level.
P0500VEHICLE SPEED
SENSORAir flow of IAC valve is limited.
P1450BAROMETRIC
PRESSURE SENSOREach control is performed based on 760 mmHg barometric pressure.
P0705 TR SWITCH A/T control is performed in priority order of L, 2, N, D, R and P.
P0720OUTPUT SPEED
SENSOR CIRCUIT
MALFUNCTIONA/T control is performed by using signal from VSS.
P0753SHIFT SOLENOID
A (#1)• A/T control using 3rd gear is performed when D range, 1st, or 2nd
gear is used.
• TCC solenoid OFF
P0758SHIFT SOLENOID
B (#2)• A/T control using 4th gear is performed when D range, 2nd or 3rd
gear is used.
• When both shift solenoids A (#1) and B (#2) failed simultaneously,
A/T control using 4th gear is always performed in D range.
• TCC solenoid OFF
P0743TCC (Lock-up)
SOLENOIDTCC (Lock-up) solenoid OFF

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-29
EGR VALVE (%)
This parameter indicates opening rate of EGR valve which controls the amount of EGR flow.
A/C SWITCH (ON/OFF)
ON : Command for operation being output from A/C amplifier to compressor.
OFF : Command for operation not being output.
PSP SWITCH (ON/OFF)
ON : PSP switch detects P/S operation. (high P/S pressure)
OFF : PSP switch not detects P/S operation.
PNP SIGNAL (Transmission Range Switch, P/N or D range)
Whether the transmission range switch (P/N position switch) at P or N range or at R, D, 2 or L range is displayed.
If at P or N range, “P/N range” is displayed and if at R, D, 2 or L range, “D range” is displayed.
FUEL TANK LEVEL (%)
This parameter indicates approximate fuel level in the fuel tank. As the detectable range of the fuel level sensor
is set as 0 to 100 %, however, with some models whose fuel tank capacity is smaller, the indicated fuel level may
be only 70 % even when the fuel tank is full.
ELECTRIC LOAD (ON/OFF)
ON : Small light switch ON or rear window defogger switch ON.
OFF : Small light switch OFF and rear window defogger switch OFF.
VSS (4-A/T) (km/h, MPH)
It is computed by using pulse signals from vehicle speed sensor on 4-speed automatic transmission.
THROT POS LEVEL (Throttle Position Level For 4-A/T, “0”, “1”, “2”, “3”, “4”,“5”,“6” or “7”)
This parameter indicates which level (zone) the throttle valve opening is in.
The throttle opening is divided into 8 levels (zones) from “0” (about idle position) to “7” (about full open) and sig-
nals are assigned to each opening level (zone). PCM controls the automatic gear change of the automatic trans-
mission by using these signals according to the signal from the TP sensor.
GEAR POSITION (1ST, 2ND, 3RD or 4TH)
The gear position is determined on the basis of the command state signals generated from PCM to shift sole-
noids A and B (#1 and #2) and displayed as shown in the table below.
SHIFT SOL #1 CON/MON (Shift Solenoid #1, A Command/monitor, ON/OFF)
CON-ON : ON command being output to shift solenoid #1, A.
CON-OFF : ON command not being output.
MON-ON : Electricity being passed to shift solenoid #1, A.
MON-OFF : Electricity not being passed.SHIFT SOLENOID-A SHIFT SOLENOID-B
DISPLAY1ST ON OFF
2ND ON ON
3RD OFF ON
4TH OFF OFF

6E2-2 ENGINE AND EMISSION CONTROL SYSTEM (SEQUENTIAL MULTIPORT FUEL INJECTION FOR H27 ENGINE)
Fuel injector.......................................... 6E2-26
Electronic Control System........................ 6E2-31
Engine control module (ECM)/
powertrain control module (PCM) ........ 6E2-31
Mass air flow sensor (MAF sensor)...... 6E2-32
Intake air temperature (IAT) sensor ..... 6E2-34
Throttle position sensor (TP sensor) .... 6E2-35
Engine coolant temperature sensor
(ECT sensor) ........................................ 6E2-36
Heated oxygen sensor (sensor 1) ........ 6E2-37
Heated oxygen sensor (sensor 2) ........ 6E2-38
Vehicle speed sensor (VSS) ................ 6E2-39
Manifold absolute pressure sensor ...... 6E2-39
Fuel level sensor (sender gauge)......... 6E2-41
Crankshaft position sensor................... 6E2-41Main relay ............................................ 6E2-41
Fuel pump relay ................................... 6E2-42
Fuel cut operation ................................ 6E2-43
Emission Control System......................... 6E2-44
EGR system (if equipped) .................... 6E2-44
EVAP canister ...................................... 6E2-45
Vacuum passage ................................. 6E2-46
PCV System ............................................ 6E2-47
PCV hose ............................................. 6E2-47
PCV valve ............................................ 6E2-47
PCV system ......................................... 6E2-48
Tightening Torque Specification.............. 6E2-48
Special Tool ............................................... 6E2-48
General Description
The engine and emission control system has 4 major sub-systems: air intake system, fuel delivery system, elec-
tronic control system and emission control system.
Air intake system includes air cleaner, mass air flow sensor, throttle body, idle air control valve and intake man-
ifold.
Fuel delivery system includes fuel pump, delivery pipe, fuel pressure regulator, fuel injectors, etc.
Electronic control system includes ECM (PCM), various sensors and controlled devices.
Emission control system includes EGR, EVAP and PCV systems.

6E2-12 ENGINE AND EMISSION CONTROL SYSTEM (SEQUENTIAL MULTIPORT FUEL INJECTION FOR H27 ENGINE)
Engine and Emission Control Input/Output Table
Diagnosis
Refer to Section 6-1.
Ignition coil with igniter
HO2S heater control
Input
Output Function
Main relay control
Fuel pump control
Injection control
Ignition control
MIL control Idle air control
EVAP purge control
EGR control
A/C control
A/C condensor fan
controlMain relay
Fuel pump relay
Injectors
MIL
EVAP canister purge
valve IAC valve
EGR valve (if equipped)
HO2S (if equipped)
A/C amplifier
(if equipped)
A/C condensor fan
relay (if equipped)
CMP sensor
MAF sensor
TP sensor
ECT sensor
IAT sensor
HO2S (sensor 1)(if equipped)
VSS
Blower fan switch
Rear defogger switch
PSP switch
Ignition switch
Starter switch
A/C amplifier (if equipped)
TR switch (A/T VEHICLE)
Light switch
Knock sensor
CO adjusting resistor (if equipped)
Test swich terminal (Vehicle with monitor connector)
Diag. swich terminal (Vehicle with monitor connector)
Brake switch (A/T VEHICLE)
ABS control module

ENGINE AND EMISSION CONTROL SYSTEM (SEQUENTIAL MULTIPORT FUEL INJECTION FOR H27 ENGINE) 6E2-39
HEATER INSPECTION
Refer to “HEATED OXYGEN SENSOR (SENSOR 1) HEATER
INSPECTION”
Vehicle speed sensor (VSS)
ON-VEHICLE INSPECTION
1) Hoist vehicle.
2) Release parking brake lever, set transmission in neutral and
transfer in “2H”.
3) Remove ECM (PCM) cover.
4) Connector voltmeter between VSS terminal C51-3-1 of ECM
(PCM) connector and body ground.
5) Turn ignition switch ON and turn rear right tire slowly with
rear left tire locked.
Voltmeter should indicate deflection between 0 – 1 V and 8 –
14 V a few times while tire (1) is turned one revolution.
If check result is not satisfactory, proceed to flow table of
“DTC P0500” in Section 6-1.
REMOVAL, INSPECTION AND INSTALLATION
Refer to “VSS Removal, Inspection or Installation” in Section 7D.
Manifold absolute pressure sensor
REMOVAL
1) Disconnect negative (–) cable at battery.
2) Disconnect connector from manifold absolute pressure sen-
sor.
3) Remove manifold absolute pressure sensor from intake
manifold.
[A]: Terminal arrangement of ECM (PCM) coupler
(viewed from harness side)
1. VSS