6-1-30 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
SHIFT SOL #2 CON/MON (Shift Solenoid #2, B Command/monitor, ON/OFF)
CON-ON : ON command being output to shift solenoid #2, B.
CON-OFF : ON command not being output.
MON-ON : Electricity being passed to shift solenoid #2, B.
MON-OFF : Electricity not being passed.
TCC SOL CON/MON (Torque Converter Clutch Solenoid Command/monitor, ON/OFF)
CON-ON : ON command being output to TCC solenoid.
CON-OFF : ON command not being output.
MON-ON : Electricity being passed to TCC solenoid.
MON-OFF : Electricity not being passed.
TRANS RANGE (Transmission Range, P, R, N, D, 2 or L)
It indicates transmission range according to transmission range switch signal.
BRAKE SW (Brake, Stop Lamp, Switch, ON/OFF)
OFF : Brake pedal is released.
ON : Brake pedal is depressed.
O/D OFF SW (Overdrive Cut Switch, ON/OFF)
OFF : Overdrive cut switch OFF.
ON : Overdrive cut switch ON.
MODE SELECT SW (Power/normal Change Switch, Power/normal)
POWER : Switch button is at POWER position.
NORMAL : Switch button is at NORMAL position.
4WD-L SW (4WD-LOW Switch, ON/OFF)
ON : Transfer lever is shifted to 4L position.
OFF : Transfer lever is shifted to 4H or 2H position.
ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE) 6-1-31
Engine Diagnosis Table
Perform troubleshooting referring to following table when ECM (PCM) has detected no DTC and no abnormality
has been found in visual inspection and engine basic inspection previously.
Condition Possible Cause Correction
Hard starting
(Engine cranks OK)Faulty idle air control system “DIAG. FLOW TABLE B-4” in this
section.
Faulty ECT sensor or MAF sensor ECT sensor or MAF sensor in Sec-
tion 6E2.
Faulty ECM (PCM) Inspection of ECM (PCM) and its
circuit in this section.
Low compression Compression check in Section
6A2.
Faulty hydraulic valve lash adjuster Valve lash adjuster in Section 6A2.
Compression leak from valve seat Valves inspection in Section 6A2.
Sticky valve stem Valves inspection in Section 6A2.
Weak or damaged valve springs Valves spring inspection in Section
6A2.
Compression leak at cylinder head gasket Cylinder head inspection in Section
6A2.
Sticking or damaged piston ring Piston ring inspection in Section
6A2.
Worn piston, ring or cylinder Cylinders, pistons and piston rings
inspection in Section 6A2.
Malfunctioning PCV valve PCV system inspection in Section
6E2.
Engine has no power
Engine overheating Refer to “OVERHEATING” in this
table.
Defective spark plug Spark plugs in Section 6F2.
Faulty ignition coil with ignitor Ignition coil in Section 6F2.
Fuel pressure out of specification
(dirty fuel filter, dirty or clogged fuel hose or
pipe, malfunctioning fuel pressure regulator,
malfunctioning fuel pump)“DIAG. FLOW TABLE B-3” in this
section.
Maladjusted TP sensor installation angle TP sensor in Section 6E2.
Faulty EGR system “DTC P0400 DIAG. FLOW TABLE”
in this section.
Faulty injector Fuel injector in Section 6E2.
Faulty TP sensor, ECT sensor or MAF sensor TP sensor, ECT sensor or MAF
sensor in Section 6E2.
Faulty ECM (PCM) Inspection of ECM (PCM) and its
circuit in this section.
Low compression Refer to the same item in “HARD
STARTING” of this table.
Dragging brakes Diagnosis in Section 5.
Slipping clutch Diagnosis in Section 7C1.
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
6-1-34 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
Poor gasoline mileage
Faulty spark plug (improper gap, heavy depos-
its, and burned electrodes, etc.)Spark plugs in Section 6F2.
Fuel pressure out of specification “DIAG. FLOW TABLE B-3” in this
section.
Faulty TP sensor, ECT sensor or MAF sensor TP sensor, ECT sensor or MAF
sensor in Section 6E2.
Faulty EGR system “DTC P0400 DIAG. FLOW TABLE”
in this section.
Faulty injector Fuel injector in Section 6E2.
Faulty ECM (PCM) Inspection of ECM (PCM) and its
circuit in this section.
Low compression Refer to the same item in “HARD
STARTING” of this table.
Poor valve seating Valves inspection in Section 6A2.
Dragging brakes Diagnosis in Section 5.
Slipping clutch Diagnosis in Section 7C1.
Thermostat out of order Thermostat in Section 6B.
Improper tire pressure Diagnosis in Section 3.
Excessive engine oil
consumptionSticky piston ring Piston cleaning in Section 6A2.
Worn piston and cylinder Cylinders, pistons and piston rings
inspection in Section 6A2.
Worn piston ring groove and ring Pistons and piston rings inspection
in Section 6A2.
Improper location of piston ring gap Pistons installation in Section 6A2.
Worn or damaged valve stem seal Valves and cylinder head in Sec-
tion 6A2.
Worn valve stem Valves inspection in Section 6A2.
Low oil pressure
Improper oil viscosity Engine oil and oil filter change in
Section 0B.
Malfunctioning oil pressure switch Oil pressure switch inspection in
Section 8.
Clogged oil strainer Oil pan and oil pump strainer clean-
ing in Section 6A2.
Functional deterioration of oil pump Oil pump in Section 6A2.
Worn oil pump relief valve Oil pump in Section 6A2.
Excessive clearance in various sliding parts “INSPECTION” for each parts 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
6-1-90 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
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 and warm up
engine completely.
3) Increase vehicle speed to 55 – 60 km/h (35 – 40 mph).
4) Keep driving above vehicle speed for 7 min. or more.
5) Increase vehicle speed to 100 – 110 km/h (60 – 70 mph).
6) Release accelerator pedal and with engine brake applied, keep vehicle coasting and then stop vehicle.
7) Check if pending DTC exists by using scan tool. If not, check if EGR system monitoring test has completed
by using scan tool. If not in both of above checks (i.e., no pending DTC and EGR system monitoring test not
completed), check vehicle conditions (environmental) and repeat Steps 3) through 6).DTC DETECTING CONDITION TROUBLE AREA
During deceleration (engine speed high with closed
throttle position) in which fuel cut is involved, difference
in intake manifold pressure between when EGR valve is
opened and when it is closed is smaller than specified
value.
(2 driving cycle detection logic)•EGR valve
• EGR passage
• Manifold absolute pressure sensor
•ECM (PCM)
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and be very careful during testing to avoid occurrence of an accident.
Road test should be carried out with 2 persons, a driver and a tester, on a level road.
NOTE:
Check to make sure that following conditions are satisfied when using this “DTC CONFIRMATION
PROCEDURE”.
Intake air temp. : – 8°C (18°F) or higher
Engine coolant temp. : – 8 – 110°C (18 – 230°F)
Altitude (barometric pressure) : 2400 m, 8000 ft or less (560 mmHg (75 kPa) or more)
1. Vehicle speed km/h (mph)
2. Step
6-1-100 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
Evap canister purge system inspection
1) Warm up engine to normal operating temperature.
2) Hoist vehicle so that all wheels rotate freely.
3) Set M/T in “Neutral” or A/T in “P” position and parking brake.
4) Disconnect purge hose (1) from EVAP canister.
5) Place finger against the end of disconnected hose (1) and
check that vacuum is not felt there when engine is running at
idle speed.
6) Release parking brake lever, set transfer in “2H” and M/T in
“1st” or A/T in “L”.
7) Also check that vacuum is felt when engine speed is
increased to higher than about 1,500 r/min. and keep it for 3
min. or more. If check result is not described in steps 5) and
7), check EVAP canister purge valve, wire harness and vac-
uum passage.
Vacuum passage inspection
Start engine and run it at idle speed. With finger placed against
vacuum nozzle (1), check that vacuum is applied.
If it is not applied, clean vacuum passage by blowing compressed
air.
WARNING:
Make sure that transfer is set to “2H” range position for
this check. If it is set to “4H” or “4L” position, front and
rear wheels turn at high speed and a very dangerous sit-
uation may occur.
1
6-1-106 ENGINE GENERAL INFORMATION AND DIAGNOSIS (H27 ENGINE)
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 and warm up
engine completely.
3) Increase vehicle speed to 100 – 110 km/h (60 – 70 mph).
4) Release accelerator pedal and with engine brake applied, keep vehicle coasting for 5 seconds or more and
then stop vehicle.
5) Check pending DTC by using scan tool.
TROUBLESHOOTING
WARNING:
When performing a road test, select a place where there is no traffic or possibility of a traffic acci-
dent and be very careful during testing to avoid occurrence of an accident.
Road test should be carried out with 2 persons, a driver and a tester, on a level road.
NOTE:
Check to make sure that following condition is satisfied when using this “DTC CONFIRMATION PRO-
CEDURE”.
Intake air temp. : – 8°C (18°F) or higher
Engine coolant temp. : – 8 – 110°C (18 – 230°F)
Altitude (barometric pressure) : 2400 m, 8000 ft or less (560 mmHg (75 kPa) or more)
Step Action Yes No
1Was “ENGINE DIAG. FLOW TABLE” per-
formed?Go to Step 2. Go to “ENGINE DIAG.
FLOW TABLE” in this
section.
2 Does speedometer indicate vehicle speed? Faulty “BLU/YEL” wire or
poor C51-1-14 connection.
If wire and connection are
OK, intermittent trouble or
faulty ECM (PCM).
Check for intermittent refer-
ring to “INTERMITTENT
AND POOR CONNECTION”
in Section 0A.Go to Step 3.
3 VSS power supply voltage check:
1) With ignition switch OFF, remove VSS
coupler.
2) With ignition switch ON leaving engine
OFF, check voltage between C20-3 and
C20-2 terminal of VSS coupler.
Is voltage 10 – 14 V?Go to Step 4.“BLK/BLU” or “BLK/YEL”
wire open/short.
4 VSS signal harness check:
1) With ignition switch ON leaving engine
OFF, check voltage between C20-1 and
C20-2 terminal of VSS coupler.
Is voltage 4 V or more?Go to Step 5. Go to Step 6.