
6-1-2 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
Table A-4 Malfunction Indicator Lamp
Check – MIL Does Not Flash or Just
Remains ON Even with Grounding
Diagnosis Switch Terminal (Vehicle with
Monitor Connector) ................................... 6-1-45
Table A-5 ECM (PCM) Power and Ground
Circuit Check – MIL Doesn’t Light at
Ignition Switch ON and Engine Doesn’t
Start Though It Is Cranked Up .................. 6-1-46
DTC P0100 (DTC No.33, 34) Mass Air
Flow Circuit Malfunction ............................ 6-1-48
DTC P0110 (DTC No.23, 25) Intake Air
Temp. (IAT) Circuit Malfunction ................ 6-1-50
DTC P0115 (DTC No.14, 15) Engine
Coolant Temp. Circuit Malfunction ............ 6-1-52
DTC P0120 (DTC No.21, 22) Throttle
Position Circuit Malfunction....................... 6-1-54
DTC P0121 Throttle Position Circuit
Range/Performance Problem ................... 6-1-56
DTC P0130 (DTC No.13) HO2S-1 (Bank 1)
Circuit Malfunction or No Activity
Detected.................................................... 6-1-58
DTC P0133 HO2S-1 (Bank 1) Circuit Slow
Response .................................................. 6-1-60
DTC P0135 HO2S-1 (Bank 1) Heater
Circuit Malfunction .................................... 6-1-61
DTC P0136 HO2S-2 (Bank 1) Circuit
Malfunction................................................ 6-1-63
DTC P0141 HO2S-2 (Bank 1) Heater
Circuit Malfunction .................................... 6-1-65
DTC P0150 (DTC No.26) HO2S-1 (Bank 2)
Circuit Malfunction or No Activity
Detected.................................................... 6-1-67
DTC P0153 HO2S-1 (Bank 2) Circuit Slow
Response .................................................. 6-1-69
DTC P0155 HO2S-1 (Bank 2) Heater
Circuit Malfunction .................................... 6-1-70
DTC P0156 HO2S-2 (Bank 2) Circuit
Malfunction................................................ 6-1-72
DTC P0161 HO2S-2 (Bank 2) Heater
Circuit Malfunction .................................... 6-1-74
DTC P0171/P0172 Fuel System Too
Lean/Rich (Bank 1) ................................... 6-1-76
DTC P0174/P0175 Fuel System Too
Lean/Rich (Bank 2) ................................... 6-1-78
DTC P0300/P0301/P0302/P0303/P0304/
P0305/P0306 Random Misfire/Cylinder 1
Misfire/Cylinder 2 Misfire/Cylinder 3 Misfire/
Cylinder 4 Misfire Detected/Cylinder 5
Misfire Detected/Cylinder 6 Misfire
Detected.................................................... 6-1-80
DTC P0325 (DTC No.43) Knock Sensor Circuit Malfunction ..................................... 6-1-82
DTC P0335 Crankshaft Position Sensor
Circuit Malfunction ..................................... 6-1-84
DTC P0340 (DTC No.42) Camshaft
Position Sensor Circuit Malfunction ........... 6-1-86
DTC P0400 Exhaust Gas Recirculation
Flow Malfunction ........................................ 6-1-89
DTC P0403 (DTC No.51) Exhaust Gas
Recirculation Circuit Malfunction ............... 6-1-92
DTC P0420 Catalyst System Efficiency
Below Threshold (Bank 1) ......................... 6-1-94
DTC P0430 Catalyst System Efficiency
Below Threshold (Bank 2) ......................... 6-1-96
DTC P0443 Evap Control System Purge
Control Valve Circuit Malfunction............... 6-1-98
Evap canister purge system
inspection ............................................. 6-1-100
Vacuum passage inspection ................ 6-1-100
Vacuum hose inspection ...................... 6-1-101
Evap canister purge valve and its
circuit inspection .................................. 6-1-101
Evap canister purge valve inspection .. 6-1-101
DTC P0460 Fuel Level Sensor Circuit
High Input ................................................ 6-1-103
DTC P0500 (DTC No.24) Vehicle Speed
Sensor Malfunction .................................. 6-1-105
DTC P0505 Idle Air Control System
Malfunction .............................................. 6-1-108
DTC P0601 (DTC No.71) Internal Control
Module Memory Check Sum Error .......... 6-1-110
DTC P1408 Manifold Absolute Pressure
Sensor Circuit Malfunction ....................... 6-1-111
DTC P1450/P1451 Barometric Pressure
Sensor Circuit Malfunction/Performance
Problem ................................................... 6-1-113
DTC P1500 Engine Starter Signal Circuit
Malfunction .............................................. 6-1-114
DTC P1510 Ecm Back-Up Power Supply
Malfunction .............................................. 6-1-115
Table B-1 Fuel Pump Circuit Inspection .. 6-1-116
Table B-2 Fuel Injectors and Circuit
Inspection ................................................ 6-1-117
Table B-3 Fuel Pressure Inspection ........ 6-1-119
Table B-4 Idle Air Control System
Inspection ................................................ 6-1-121
Table B-5 A/C Signal Circuits Inspection
(If Equipped) ............................................ 6-1-123
Table B-6 A/C Condenser Fan Motor
Relay Control System Inspection
(If Equipped) ............................................ 6-1-124
Special Tool ............................................... 6-1-125

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.

6-1-20 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
P0174 Fuel system too lean (Bank 2)Short term fuel trim or total fuel trim
(short and long terms added) is larger
than specification for specified time or
longer. (Fuel trim toward rich side is
large.)2 driving
cyclesNot
applicable
P0175 Fuel system too rich (Bank 2)Short term fuel trim or total fuel trim
(short and long terms added) is
smaller than specification for specified
time or longer. (Fuel trim toward lean
side is large.)2 driving
cyclesNot
applicable
P0300
P0301
P0302
P0303
P0304
P0305
P0306Random misfire detected
Cylinder 1 misfire detected
Cylinder 2 misfire detected
Cylinder 3 misfire detected
Cylinder 4 misfire detected
Cylinder 5 misfire detected
Cylinder 6 misfire detectedMisfire of such level as to cause dam-
age to three way catalystMIL flashing
during mis-
fire detec-
tionNot
applicable
Misfire of such level as to deteriorate
emission but not to cause damage to
three way catalyst2 driving
cyclesNot
applicable
P0325
(No.43)Knock sensor circuit malfunc-
tionSensor output too low
1 driving
cycle1 driving
cycle
Sensor output too high
P0335Crankshaft position sensor cir-
cuit malfunctionNo signal during engine running and
CMP sensor signal inputting1 driving
cycleNot
applicable
P0340
(No.42)Camshaft position sensor cir-
cuit malfunctionNo signal for 3 sec. during engine
cranking, REF signal pattern incor-
rect or POS signal voltage too high or
too low1 driving
cycleNot
applicable
P0400Exhaust gas recirculation flow
malfunction detectedExcessive or insufficient EGR flow.2 driving
cyclesNot
applicable
P0403
(No.51)EGR valve circuit malfunctionEGR valve electrical circuit open or
shot to ground1 driving
cycle1 driving
cycle
P0420Catalyst system efficiency
below threshold (Bank 1)Output waveforms of HO2S-1 and
HO2S-2 are similar.
(Time from output voltage change of
HO2S-1 to that of HO2S-2 is shorter
than specification.)2 driving
cyclesNot
applicable
P0430Catalyst system efficiency
below threshold (Bank 2)Output waveforms of HO2S-1 and
HO2S-2 are similar.
(Time from output voltage change of
HO2S-1 to that of HO2S-2 is shorter
than specification.)2 driving
cyclesNot
applicable
P0443Purge control valve circuit
malfunctionPurge control valve circuit is open or
shorted to ground.2 driving
cyclesNot
applicable
P0500
(No.24)Vehicle speed sensor mal-
functionNo signal while running in “D” range
or during fuel cut at decelerating.2 driving
cycles1 driving
cycle DTC NO. DETECTED ITEMDETECTING CONDITION
(DTC will set when detecting : )MIL
(vehicle
without
monitor
connector)MIL
(vehicle
with
monitor
connector)

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-33
Surges
(Engine power varia-
tion under steady
throttle or cruise.
Feels like the vehicle
speeds up and down
with no change in the
accelerator pedal.)Defective spark plug
(excess carbon deposits, improper gap, and
burned electrodes, etc.)Spark plugs in Section 6F2.
Variable fuel pressure
(clogged fuel filter, kinky or damaged fuel hose
and line, faulty fuel pressure regulator)“DIAG. FLOW TABLE B-3” in this
section.
Faulty EGR system “DTC P0400 DIAG. FLOW TABLE”
in this section.
Faulty MAF sensor MAF sensor in Section 6E2.
Faulty injector Fuel injector in Section 6E2.
Faulty ECM (PCM) Inspection of ECM (PCM) and its
circuit in this section.
Excessive detonation
(The engine makes
sharp metallic knocks
that change with throt-
tle opening. Sounds
like pop corn pop-
ping.)Engine overheating Refer to “OVERHEATING” in this
table.
Faulty spark plug Spark plugs in Section 6F2.
Improper ignition timing Ignition timing in Section 6F2.
Clogged fuel filter and fuel lines Fuel pressure check in Section
6E2.
Faulty EGR system “DTC P0400 DIAG. FLOW TABLE”
in this section.
Faulty ECT sensor or MAF sensor ECT sensor or MAF sensor in Sec-
tion 6E2.
Faulty injector Fuel injector in Section 6E2.
Faulty ECM (PCM) Inspection of ECM (PCM) and its
circuit in this section.
Excessive carbon deposits in combustion
chamberPiston and cylinder head cleaning
in Section 6A2.
Poor knock sensor performance “DTC P0325 DIAG. FLOW TABLE”
in this section.
Overheating
Inoperative thermostat Thermostat in Section 6B.
Poor water pump performance Water pump in Section 6B.
Clogged or leaky radiator Radiator in Section 6B.
Improper engine oil grade Engine oil and oil filter change in
Section 0B.
Clogged oil filter or oil strainer Oil pressure check in Section 6A2.
Poor oil pump performance Oil pressure check in Section 6A2.
Dragging brakes Diagnosis in Section 5.
Slipping clutch Diagnosis in Section 7C1.
Blown cylinder head gasket Cylinder head inspection in Section
6A2. Condition Possible Cause Correction

6-1-38 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
E61-22A/C condenser fan motor relay
(if equipped)10 – 14 VIgnition switch ON, A/C not oper-
ated and Engine coolant temp. :
less than 113°C, 235°F
E61-23 Fuel pump relay0 – 2.5 VFor 3 sec. after ignition switch ON
or while engine running
10 – 14 VAfter 3 sec. from ignition switch ON
with engine stopped
E61-24Ground for CO adjusting resistor
(if equipped)––
E61-25 – – –
E61-26 – – –
E61-27 – – –
E61-28 Fuel level sensor 0 – 6 VIgnition switch ON
Voltage depends on fuel level
E61-29Diag. switch terminal
(vehicle with monitor connector)10 – 14 V Ignition switch ON
E61-30 ABS control module 10 – 14 V Ignition switch ON
E61-31Power/Normal change switch
(A/T vehicle)0 – 1 VIgnition switch ON, P/N change
switch : POWER mode
10 – 14 VIgnition switch ON, P/N change
switch : NORMAL mode
E61-32 Lighting switch0 – 1 VIgnition switch ON, lighting switch
OFF
10 – 14 VIgnition switch ON, lighting switch
ON
E61-33 Overdrive cut switch (A/T vehicle)10 – 14 VIgnition switch ON, overdrive cut
switch released
0 – 1 VIgnition switch ON, overdrive cut
switch pressed
E61-34 Stop lamp switch0 – 1 VBrake pedal released (switch OFF),
Ignition switch ON
10 – 14 VBrake pedal depressed (switch ON),
Ignition switch ON
E61-35 Cruise control module (if equipped) 10 – 14 V Ignition switch ON
C51-3-1 Intake air temp. sensor 2.2 – 3.0 VIgnition switch ON, Sensor ambient
temp. : 20°C, 68°F
C51-3-2 Engine coolant temp. sensor 0.5 – 0.9 VIgnition switch ON, Engine coolant
temp. : 80°C, 176°F
C51-3-3 Knock sensor About 2.5 VWith engine running at idle after
warned up
C51-3-4 Power source 10 – 14 V Ignition switch ON
C51-3-5 Ground for MAF sensor – –
C51-3-6 Ground – –
C51-3-7 4WD switch0 – 1 VIgnition switch ON, Transfer lever :
4H or 4L range
10 – 14 VIgnition switch ON, Transfer lever :
2H range
C51-3-8 Manifold absolute pressure sensor 3.3 – 4.3 V Ignition switch ON and engine stops TERMINAL CIRCUIT NORMAL VOLTAGE CONDITION

6-1-82 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
DTC P0325 (DTC No.43) Knock Sensor Circuit Malfunction
CIRCUIT DESCRIPTION
DTC DETECTING CONDITION AND TROUBLE AREA
DTC CONFIRMATION PROCEDURE
1) Connect scan tool to DLC with ignition switch OFF.
2) Turn ON ignition switch and clear DTC, pending DTC and freeze frame data by using scan tool.
3) Start engine and run it for 10 sec.
4) Check DTC by using scan tool.
1. Knock sensor
2. ECM (PCM)
DTC DETECTING CONDITION TROUBLE AREA
DTC will set when one of the following condition is
detected.
• KNOCK sensor voltage is 0.90 V or less, or
• KNOCK sensor voltage is 3.98 V or more• “WHT” circuit open or shorted to ground
• KNOCK sensor malfunction
• ECM malfunction

ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-83
TROUBLESHOOTING
Fig. for Steps 2 and 3Step Action Yes No
1 Was “ENGINE DIAG. FLOW TABLE” per-
formed?Go to Step 2. Go to “ENGINE DIAG.
FLOW TABLE” in this
section.
2 Knock sensor and its circuit check :
1) With engine running, check voltage from
“C51-3-3” terminal of ECM connector to
body ground. See Fig.
Is voltage about 0.90 – 3.98 V?Knock sensor and its cir-
cuit are in good condition.
Intermittent trouble or
faulty ECM.
Recheck, referring to
“INTERMITTENT TROU-
BLE” in Section 0A.Go to Step 3.
3 Knock sensor power source circuit check :
1) Stop engine.
2) With ignition switch at OFF position, discon-
nect knock sensor connector.
3) With ignition switch at ON position, check
voltage from “WHT” to body ground terminal
of knock sensor connector. See Fig.
Is it 4 – 5 V?Substitute a known-good
knock sensor and
recheck.“WHT” wire open, shorted
to ground circuit or poor
“C51-3-3” connection.
If wire and connection are
OK, substitute a known-
good substitute a known-
good ECM and recheck.
1. Knock sensor
2. Knock sensor connector

ENGINE MECHANICAL (H27 ENGINE) 6A2-27
12) Disconnect the following electric lead wires :
•Injector wire coupler
•CMP sensor coupler
•Ignition coil couplers
•CKP sensor coupler
•MAP sensor coupler
•TP sensor (1) coupler
•IAC valve (2) coupler
•Earth wire (3) from surge tank
•EVAP canister purge valve coupler
•EGR valve coupler
•Oxygen sensor -1 and -2 couplers referring to “Exhaust Man-
ifold” in this section
•Coolant temperature sensor coupler
•Knock sensor coupler
•Generator wires
•Starter wires
•Oil pressure wire
•P/S pump wire
•Earth wire from generator bracket
•Engine block heater (if equipped)
13) Remove clamps and brackets.
14) Disconnect the following hoses :
•Heater hose from heater water pipe
•Heater hose from water outlet cap
•EVAP canister hose from canister pipe
•Brake booster vacuum hose
15) Remove EVAP canister purge valve (5).
16) Disconnect the following hoses at the location shown in the
figure :
•Fuel feed hose (1) from fuel feed pipe
•Fuel return hose from (2) fuel return pipe
17) Remove P/S pump assembly. Refer to “POWER STEERING
PUMP” in Section 3B1.
18) Remove A/C compressor assembly. Refer to “COMPRES-
SOR ASSEMBLY” in Section 1B.
19) Remove steering shaft lower assembly. Refer to “STEERING
LOWER SHAFT ASSEMBLY” in Section 3C1.
20) Raise vehicle.
21) Remove front differential housing with differential from chas-
sis if equipped. Refer to “DISMOUNTING” in Section 7E.
22) Remove exhaust No.1 pipe. Refer to “EXHAUST MANI-
FOLD” in this section.
23) Remove exhaust manifold stiffener from transmission.
4. Clamp bracket
6. EGR valve
7. Heater hose
2
14
3
75
6