fuel ISUZU TROOPER 1995 Owners Manual

6E2-42 DRIVEABILITV AND EMISSIONS
CHART A-3
(Page 1 of 3)
ENGINE CRANKS BUT WILL NOT RUN
Circuit Description:
Before using this chart, battery condition, engine cranking speed, and fuel quantity should be checked and verified
as being OK.
Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
CD A malfunction indicator lamp "ON" is basic test to determine if there is battery positive voltage and ignition
voltage supplied to the Engine Control Module (ECM). No data link connector data may be due to an ECM
problem. CHART A-2 will diagnose the ECM. If throttle position sensor voltage is over 2.5 volts, the engine
may be in the
"clear flood" mode, which will cause starting problems. The engine will not start without
reference pulses and, therefore, the "Scan tool" should indicate engine speed during cranking.
@ Because the electronic ignition system uses two plugs and wires to complete the circuit of each coil, the
opposite spark
should be left connected. If revolution per minute was indicated during crank, the ignition
control module is receiving a crank signal, but no spark at this test indicates the Ignition Control Module (ICM)
is not triggering the coils.
® The test light should blink, indicating the ECM is in control of the injectors. How bright the light blinks is not
important. However, the test light should be a J-34730-3 or equivalent.
@ This test will determine if the ignition control module is not generating the reference pules or if the wiring or
ECM are at fault. By touching and removing a test light to 12 volts on VEL/RED wire, a reference pulse should
be generated. If revolution per minute is indicated, the ECM and wiring are OK.
® High resistance in the spark plug wire could cause a "no start" condition. If a spark plug wire is found to be
faulty, replace it and retest system.
(SOHC)
I"M"
TOECM RED/GRN #1 BLU/YEL MAIN RED/GRN #2 BLU/YEL
RELAY
tRED/GRN
RED/GRN #3 BLU/YEL
RED/GRN #4 BLU/YEL
RED/GRN
#5 BLU/YEL
RED/GRN
#6 BLU/YEL
FUEL
INJECTORS ENGINE
CONTROL MODULE(ECM)
INJECTOR
RED/GRN
RED/GRN
RED/GRN
RED/GRN
RED/GRN
RED/GRN
IDOHCI BLU/YEL
BLU/YEL
l 1.3!l INJECTOR RESISTOR 1_
ORG/BLU
--+----
E~INE YEL/GRN D11 BLK/ORN -4>-BLK/YEL ----41sv---TO IGN BLK/RED -TOTACHOMETER SWITCH
BLK --:::L =
AND TCM (C91-D12)
CRANKSHAFT
POSITION
1 SENSOR
-........:::SHIELD
Fig. 6E2-26
•

6E2-44 DRIVEABILITV AND EMISSIONS
CHART A-3
(Page 2 of 3)
ENGINE CRANKS BUT WILL NOT RUN
Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
CD This will check the injector harness for an "open" or "shorted" circuit after the engine harness connector.
® A shorted or resistance injector could be the cause of a "cranks but won't run" symptom.
® Test for a short to ground in the injector driver circuits.
@ Check for voltage at the injector. An "open" in the RED/GRN wire at the splice from the main relay would
result in a "crank but won't run" symptom.
@ Test the engine control module for a injector pulse.
® A faulty resistor module could be the cause of a no start. If module was found to be faulty, recheck the engine
control module after replacement of the resistor module.
INJECTOR
RED/GRN BLU!YEL
RED/GRN
RED/GRN
(SOHC) RED/GRN
RED/GRN
1,------RED/GRN --------t~-R-E-D/:_G_R_N----'
TOECM MAIN RELAY
LED/GRN
RED/GRN #1 BLU!YEL
RED/GRN
#2 BLU!YEL
RED/GRN #3 BLU!YEL
RED/GRN #4 BLU!YEL
RED/GRN #5 BLU!YEL
RED/GRN #6 BLU!YEL
FUEL
INJECTORS (DOHC)
BLU!YEL
BLU!VEL1 INJECTOR
RESISTOR BLU/GRN
L ORG/BLU ----411f----ORG/BLU
c__ __ ORG/BLU
~---------------VEL
~---------------YE~RED
~-----------------YE~BLU
~--------------~ YE~GRN D11 Ef'WINE . BLKJORN ~>-
BLKJRED _____.
BLK -::L
BLK/YEL ___.,5~ TO IGN
TO TACHOMETER SWITCH
AND TCM (C91-D12)
WHT----i:'---'r,--1 CRANKSHAFT
BLK --___.~ i POSITION ' :
1 SENSOR WHT/RED ~~,_7,::-L!...LJ
'SHIELD
Fig. 6E2-27
ENGINE CONTROL
MODULE(ECM)
1 and 2 fuel injector
3 and 4
fuel injector
5 and 6
fuel injector
•

DRIVEABILITV AND EMISSIONS 6E2-45
CHART A-3
.(hfi 2 of 3)
ENGINE CRANKS BUT WILL NOT RUN
FROM CHART A-3 (1 OF 3) I l j_ I
BLINKING LIGHT I STEADY LIGHT I NO LIGHT j
I
I @ • RECONNECT THE BLUE AND @ • IGNITION "OFF". •
BACK PROBE ECM AT TERMINAL BLACK ENGINE HARNESS • DISCONNECT ENGINE CONTROL C11,
C14, D15 AND D16 WITH
CONNECTORS. MODULE (ECM) CONNECTORS. TEST LIGHT TO BATTERY • REFER TO $E.CR01111:2 FOR • PROBE ECM TERMINALS C11, POSITIVE
VOLTAGE.
INTAKE PLENUM REMOVAL. C14, D15 AND D16 WITH TEST •
NOTE LIGHT WHILE CRANKING,
• WITH INTAKE PLENUM REMOVE LIGHT TO BATTERY POSITIVE SHOULD
BLINK.
DISCONNECT AND CHECK AT VOLTAGE. DOES IT? LEAST TWO INJECTORS
WITH LIGHT
SHOULD BE "OFF" ON ALL
THE INJECTOR TEST LIGHT TERMINALS. J34730-B. IS IT? TESTER SHOULD BLINK WHILE I CRANKING ENGINE.
~ ~ ~ $
DOES IT?
SHORT TO GROUND IN I FAULTY I
OPEN IN INJECTOR II FAUL TV
J CIRCUIT THAT LIGHT ECM DRIVER CIRCUIT(S). ECM WAS "ON".
~ $
• CHECK RESISTANCE OF @ • IGNITION "ON". INJECTORS, SHOULD BE 1.2 -3.0 • TEST LIGHT CONNECTED TO GROUND.
OHMS. • PROBE RED/GRN WIRE AT ANY INJECTOR.
• REPLACE ANY INJECTOR THAT LIGHT SHOULD BE "ON". WAS NOT CORRECT. IS IT? IF ALL WERE OK, REFER TO I CHART A-7 TO TEST FUEL
$ ~
PRESSURE.
• TEST LIGHT CONNECTED TO OPEN IN CIRCUIT BATTERY POSITIVE VOLTAGE BETWEEN INJECTORS PROBE BLUIYEL (DOHC} WIRE OR AND ECM MAIN BLU/YEL, ORG/BLU AND BLU/GRN RELAY. (SOHC) OF ANY INJECTOR.
NOTE LIGHT WHILE CRANKING
THE ENGINE.
LIGHT SHOULD "BLINK".
DOES
IT?
I
$
I
I NO (SOHCll NO (DOHC)j
®
I REFER TO CHART A-7 TO
I
• IGNITION "OFF". TEST FUEL PRESSURE. • DISCONNECT INJECTOR
RESISTOR MODULE.
• USING
DVOM MEASURE RESISTANCE OF THE MODULE BETWEEN THE BLU/YEL WIRE AND THE BLU/GRN WIRE.
SHOULD HAVE 2.7 OHMS ±10%. DOES IT?
$ $
REPAIR OPEN REPLACE INJEC-IN THE INJEC- TOR
RESISTOR
TOR DRIVER MODULE
CIRCUIT(S).

6E2-46 DRIVEABILITV AND EMISSIONS
CHART A-3
(Page 3 of 3)
ENGINE CRANKS BUT WILL NOT RUN
Circuit Description:
If the "Scan tool" did not indicate a engine speed and there is no spark present at the plugs, the problem lies in the
electronic ignition system
or the power and ground supplies to the module.
The magnetic crankshaft position is used to determine engine crankshaft position sensor much the same way as
the pick-up coil did in distributor type systems. The sensor is mounted in the block near a seven slot wheel on the
crank shaft. The rotation
of the wheel creates a flux change in the sensor which produces a voltage signal. The
Ignition Control Module (ICM) then processes this signal and creates the reference pulses needed by the engine
control module and the signal triggers the correct coil at the correct time.
Test Description: Numbers below refer to circled ® Checks for continuity of the crankshaft position
numbers on the diagnostic chart. sensor and connections.
good ground is
available at the ICM. cranking speed of engine.
® Tests for battery positive voltage in Ignition Feed
Circuit to the
ICM.
TO ECM RED/GRN #1 BLU/YEL MAIN RELAY
tRED/GRN
RED/GRN #2 BLU/YEL
RED/GRN #3 BLU/YEL
RED/GRN '"#4 BLU/YEL RED/GRN #5 BLU/YEL RED/GRN #6 BLU/YEL
FUEL
INJECTORS INJECTOR
RED/GRN RED/GRN RED/GRN
E"'QINE YELJGRN D11 BLK!ORN ----)>--BLK!YEL _____..,-~ TO IGN BLK!RED
-TO TACHOMETER SWITCH BLK --:::J_ AND TCM (C91-D12)
WHT2cl]= :-·-, 2 CRANKSHAFT BLK ~ : POSITION WHT/RED · __ ,' 1 SENSOR
'-;SHIELD
Fig. 6E2-28
ENGINE CONTROL
MODULEIECM)
1 and 2 fuel injector
•

6E2-48 DRIVEABILITY AND EMISSIONS
CHART A-5
FUEL PUMP RELAY CIRCUIT
Circuit Description:
When the ignition switch is turned "ON", the Engine Control Module (ECM) will activate the ft:Jel pump relay and
operate the in-tank
fuel pump. The fuel pump will operate as long as the engine is cranking or running and the ECM
is receiving ignition reference pulses. If there are no reference pulses, the ECM will shut "OFF" the fuel pump
within 2 seconds after key
"ON".
Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
CD Checks for the presence Battery Position Voltage at switching portion of fuel pump relay.
® Checks circuit between fuel pump relay and ground (including the fuel pump).
® This test will confirm if voltage is available to the relay coil.
Diagnostic Aids:
A visual inspection of wiring and connectors should be made if an intermittent problem exists. For more
information, see
"lntermittents" in "Symptoms," Section "6E2-B".
ECM
FUEL PUMP
RELAY
H02S HEATER _. ___ .,.TO H02S HEATER
10 A BODY HARNESS CONNECTOR (WHITE)
RED/WHT 1---_.__.., '"..._.. __ BLK!RED...J
_[BLK
-= LOCATED PASSENGER SIDE CHASSIS
GROUND
CONNECTOR
TO MAIN RELAY
RED/WHT---+-ECM TERMINALS "81", "C16", 11A6" AND FUEL INJECTORS
FACE VIEW FUEL PUMP RELAY SOCKET
BLK
j__
IN TANK FUEL PUMP
TO BATIERY IN UNDERHOOD ENGINE
CONTRO:-- MODULE(ECM) ·.
FUEL PUMP RELAY DRIVER
8+
VOLTAGE
FUSE/RELAY
i L---------------------------C-EN_T_E_R _______________________ ~
lL---f~. 6E2=29
/
'"·:c·t( (7.::!11t.~ l<(/1) 1/. i-
•

DRIVEABILITV AND EMISSIONS 6E2-49
CHART A-5
FUEL PUMP RELAY CIRCUIT
• REMOVE FILL CAP. • IGNITION "ON", ENGINE STOPPED.
• LISTEN FOR PUMP TO RUN AT FILLER NECK. • PUMP SHOULD RUN FOR 2 SECONDS, THEN SHUT "OFF". DOES IT?
I
CD
$ $
• REMOVE RELAY FROM UNDERHOOD RELAY CENTER. INTERMITTENT PROBLEM. SEE I • WITH TEST LIGHT TO GROUND, PROBE RED/WHT "DIAGNOSTIC AIDS" ON FACING~. WIRE CAVITY OF FUEL PUMP RELAY CONNECTOR.
• LIGHT SHOULD BE "ON". IS IT?
I
$
$
• JUMPER RED/WHT WIRE AND BLK/RED WIRE WITH A OPEN IN RED/WHT WIRE CIRCUIT. I FUSED JUMPER. • LISTEN FOR FUEL PUMP TO RUN. DOES IT?
I
$ $
• IGNITION "OFF" FOR 10 SECONDS. • JUMPER WIRE STILL IN PLACE. ® • CONNECT TEST LIGHT BETWEEN BLK WIRE AND • PROBE FUEL PUMP CONNECTOR AT FUEL
PNK/WHT WIRE OF FUEL PUMP RELAY CONNECTOR. TANK WITH TEST LIGHT TO GROUND. • IGNITION "ON", LIGHT SHOULD BE "ON" FOR 2 • LIGHT SHOULD BE "ON". SECONDS, THEN SHUT "OFF". IS IT? IS IT?
I
$
$ ~ $
• IGNITION "OFF" FOR 10 SECONDS. I FAULTY RELAY I OPEN IN GROUND TO I OPEN IN BLK/RED WIRE I • BACK PROBE TERMINAL "C3" OF FUEL PUMP ENGINE CONTROL MODULE (ECM) OR WITH TEST LIGHT TO GROUND. FAULTY FUEL PUMP • IGNITION "ON". • LIGHT SHOULD BE "ON" FOR 2 SECONDS.
IS IT?
I
$ $
OPEN IN PNK/WHT WIRE FAULTY ENGINE OR CONTROL MODULE
OPEN IN BLK WIRE (ECM)

6E2-50 DRIVEABILITY AND EMISSIONS
Circuit Description:
CHART A-7
FUEL SYSTEM PRESSURE TEST
(Page 1 of 3)
The fuel pump delivers fuel to the fuel rail and injectors, where the system pressure is controlled from 280 to 320
kPa (41 to 46 psi) by the fuel pressure control valve. Excess fuel is returned to the fuel tank. When the engine is
stopped, the
pump can be energized by jumping the fuel pump relay connector with a fused jumper.
Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
CD Use pressure gauge J-34730-1. Wrap a shop towel around the fuel pressure tap to absorb any small amount
offuelleakage that may occur when installing the gauge. (The pressure will not leak down after the fuel pump
is stopped on a correctly functioning system.)
® While the engine is idling, manifold absolute pressure is low (high vacuum). When this is applied to the fuel
regulator
diaphragm the vacuum will result in a lower fuel pressure at about 190-200 kPa (25-30 psi)
@ The application of high vacuum to the fuel pressure control valve should result in a fuel pressure drop.
@ Fuel pressure leak-down may be caused by one of the following:
• Fuel
pump check valve not holding.
•
Pump coupling hose leaking.
• Fuel
pressure control valve leaking.
• Injector
sticking open/leaking.
Diagnostic Aids:
Improper fuel system pressure may contribute to one or all of the following symptoms:
• Cranks but will not run.
• Diagnostic trouble code 44 or 45.
• Cutting out (May feel like ignition problem).
•
Hesitation, loss of power or poor fuel economy.
Refer
to "Symptoms", Section "6E2-B".
SHRADER FITTING
FUEL PRESSURE
GAUGE
J-34730-1
Fig. 6E2-30
MANIFOLD VACUUM
FUEL PRESSURE CONTROL VALVE
FUEL RETURN LINE
FUEL FILTER
PUMP INLET FILTER

DRIVEABILITV AND EMISSIONS 6E2-51
CHART A-7
(PJtge 1 of 3}
FUEL SYSTEM PRESSURE TEST
NOTE: FUEL SYSTEM IS UNDER PRESSURE. TO AVOID FUEL SPILLAGE, REFER TO FIELD SERVICE PROCEDURES FOR TESTING OR REPAIRS
REQUIRING DISASSEMBLY OF FUEL LINES OR FITTINGS. REFER TO~ 3 OF 3 OF THIS CHART.
CD • INSTALL FUEL PRESSURE GAUGE, J34730-1 OR EQUIVALENT, SEE CHART A-7 ~3 OF 3) FOR INSTALLATION PROCEDURE.
• DISCONNECT VACUUM HOSE FROM FUEL PRESSURE CONTROL VALVE.
• IGNITION MUST BE "OFF" FOR 10 SECONDS.
• TURN IGNITION "ON". FUEL PUMP SHOULD RUN FOR ABOUT 2 SECONDS.
• NOTE FUEL PRESSURE AFTER PUMP STOPS.
• FUEL PRESSURE SHOULD BE 280-320 kPa (41-46 PSI) AND HOLDING STEADY. IS IT?
I
• START AND IDLE ENGINE AT NORMAL OPERATING TEMPERATURE. • RECONNECT VACUUM LINE.
• FUEL PRESSURE SHOULD HAVE
DROPPED SLIGHTLY.
DID IT?
I
@ FUEL PRESSURE
WITHIN SPECIFICATION,
BUT NOT HOLDING.
• IGNITION "OFF".
.---'---$YES
-$r---'--NO -
@ • DISCONNECT VACUUM NO TROUBLE •
CONNECT FUSED
JUMPER FROM BATTERY POSITIVE
VOLTAGE TO FUEL PUMP
RELAY CONNECTOR BETWEEN THE BLK/RED WIRE AND RED/WHT WIRE IN ENGINE
COMPARTMENT.
HOSE FROM
FUEL FOUND. REFER PRESSURE CONTROL TO "DIAGNOSTIC
VALVE. AIDS" ON
• WITH ENGINE IDLING. FACING P.A@f. APPLY 12-14"
HYDRAGYRUM OF VACUUM TO FUEL PRESSURE CONTROL
VALVE
•
FUEL PRESSURE SHOULD DROP SLIGHTLY.
DID IT?
I
• GRADUALLY BLOCK FUEL PRESSURE LINE BY PINCHING FLEX HOSE.
• REMOVE JUMPER FROM
TEST CONNECTOR WHILE
CONTINUING TO BLOCK
PRESSURE LINE.
• PRESSURE SHOULD HOLD.
DID
IT?
I PRESSURE
OUT OF SPECIFICATION.
I USE,.eAef 2 OF THIS CHART.
I
INO I PRESSURE
I
I USE CHART I A-5
~~NLO------------------~ $~YELS---------------------, LOCATE AND CORRECT
CAUSE OF INTERRUPTED
MANIFOLD ABSOLUTE
PRESSURE SUPPLY TO
REGULATOR. FUEL PRESSURE
CONTROL VALVE ASSEMBLY
IS FAULTY.
• REPEAT ABOVE PROCEDURE CHECK FOR WHILE BLOCKING FUEL -LEAKING PUMP COUPLING HOSE. RETURN LINE INSTEAD OF -FAUL TV IN-TANK PUMP PRESSURE LINE BY PINCHING FLEX HOSE.
• PRESSURE SHOULD HOLD.
DID
IT?
LOCATE AND REPLACE LEAKING INJECTOR AND DRY SPARK PLUGS
FROM FLOODED
CYLINDERS.
FUEL PRESSURE
CONTROL VALVE
ASSEMBLY
IS FAULTY.

6E2-52 DRIVEABILITV AND EMISSIONS
CHART A-7
(Page 2 of 3)
FUEL SYSTEM PRESSURE TEST
Circuit Description:
The fuel pump delivers fuel to the fuel rail and injectors, where the system pressure is controlled from 280 to 320
kPa (41 to 46 psi) by the fuel pressure control valve. Excess fuel is returned to the fuel tank. When the engine is
stopped, the
pump can be energized by jumping the fuel pump relay connector with a fused jumper.
Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
® Pressure less than 280 kPa (41 psi) may be caused by one of two problems.
• The regulated fuel pressure is too low. The system will be running lean and may set diagnostic trouble code
44. Also, hard cold starting and overall poor performance is possible.
• Restricted flow is causing a pressure drop. Normally, a vehicle with a fuel pressure loss at idle will not be
driveable. However,
if the pressure drop occurs only while driving, the engine will surge and then stop as
pressure begins to drop rapidly.
® Restricting the fuel return line allows the fuel pump to build above regulated pressure. When battery positive
voltage is applied to the fuel pump relay, pressure should
be above 450 kPa (65 psi).
® This test determines if the high fuel pressure is due to a restricted fuel return line or a fuel pressure control
valve problem.
SHRADER FITIING
FUEL PRESSURE GAUGE J-34730-1
Fig. 6E2-31
MANIFOLD VACUUM
FUEL PRESSURE CONTROL VALVE
FUEL RETURN
LINE
FUEL FILTER
PUMP INLET FILTER
•

DRIVEABILITV AND EMISSIONS 6E2-53
CHART A-7
(P«ge 2 of 3)
FUEL SYSTEM PRESSURE TEST
NOTE: FUEL SYSTEM IS UNDER PRESSURE. TO AVOID FUEL SPILLAGE, REFER TO FIELD SERVICE PROCEDURES FOR TESTING OR REPAIRS
REQUIRING DISASSEMBLY OF FUEL LINES OR FITIINGS. REFER TO PAGE 3 OF 3 OF THIS CHART.
FROM CHART A-7 E!A:8E 1 PRESSURE OUT OF SPEC.
LOW PRESSURE I
(j) • CHECK FOR RESTRICTED IN-LINE FILTER. I IS FILTER OK?
® ~ $
• IGNITION "OFF"
REPLACE FILTER I • APPLY BATIERY POSITIVE AND RE-TEST.
VOLTAGE TO FUEL PUMP RELAY CONNECTOR USING A FUSED JUMPER
WIRE WITH FUEL PUMP RELAY
REMOVED.
• GRADUALLY BLOCK FUEL
RETURN LINE BY PINCHING
FLEXIBLE HOSE AND NOTE FUEL PRESSURE.
• FUEL PRESSURE SHOULD BE ABOVE 450 kPa (psi) IS IT?
~ $
FUEL PRESSURE CHECK IN-TANK PUMP
CONTROL VALVE ASSEMBLY FOR ASSEMBLY IS FAULTY.
-FAULTY FUEL PUMP -LEAKING COUPLING HOSE -INCORRECT PUMP. HIGH
PRESSURE
I
• DISCONNECT VACUUM LINE TO PRESSURE REGULATOR. • DISCONNECT FUEL RETURN LINE FLEXIBLE HOSE.
• ATIACH AS/16. I.D. FLEX HOSE TO PRESSURE REGULATOR SIDE OF RETURN LINE AND INSERT THE OTHER END INTO AN APPROVED GASOLINE
CONTAINER.
• NOTE FUEL PRESSURE WITHIN 2 SECONDS AFTER IGNITION IS TURNED "ON" • FUEL PRESSURE SHOULD BE 280-320 (41-46 PSI).
IS IT?
CfJ ~ FUEL PRESSURE LOCATE AND REPAIR
CONTROL VALVE RESTRICTED FUEL ASSEMBLY IS FAULTY. RETURN LINE.