fuse chart ISUZU TROOPER 1995 User Guide

6E2-38 DRIVEABILITV AND EMISSIONS
CHART A-1
WILL NOT FLASH DIAGNOSTIC TROUBLE CODE (DTC) 12
NO "CHECK ENGINE" MALFUNCTION INDICATOR LAMP (MIL)
Circuit Description:
There should always be a steady "Check Engine" Malfunction Indicator Lamp (MIL), when the ignition is "ON" and
engine stopped. Battery positive
voltage is supplied directly to the light bulb. The Engine Control Module (ECM)
will control the light and turn it "ON" by providing a ground path through the VL T wire from the ECM to the bulb.
Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
CD The Test Light provides a ground source to the "Check Engine" MIL. If the circuit is okay the "Check Engine"
MIL should
be "ON" when the terminai"A5" is probed.
® Battery feed terminals "C16" and "B1" are protected by a 30 amp ECM fusible link in relay/fuse center under
the hood near the battery.
If terminals "C16" and "B1" have voltage, the ECM grounds or the ECM are faulty.
® Using a test light connected to 12 volts, probe each of the system ground circuits to be sure a good ground is
present. Refer to the
"ECM Terminal End View" in front of this section for ECM pin locations of ground
circuits.
Diagnostic Aids;
Engine runs OK, check;
• Faulty light bulb.
•
VL T wire open.
• Meter fuse blown. This will result in no oil or generator lights, seat belt reminder, etc.
Engine cranks, but
will not run.
• Continuous battery-fuse or fusible link open. • Ignition RED/GRN wire to ECM open.
• ECM ignition fuse open. • Poor connection to ECM.
• Battery RED/WHT wire to ECM open.
TO FUEL .._..,==~ ,__,__-----, PUMP 15A
RELAY .--------~~-RED/WHT Engine
Control
Module(ECM)
BATIERY VOLTAGE
INPUT
ECM FUSIBLE RED/WHT TO LINK 30A '\.. BATIERY ~ VOLTAGE---BLK!RED ~---.-RED/WHT
TO IGNITION - BLK!YEL ~~~-BLK!YEL --'--'~"'---..__
SWITCH TO EGR VALVE VSV
CANISTER PURGE VSV
SECONDARY INTAKE VSV
REED VALVE VSV TO KS MODULE
LOCATED
PASSENGER
SIDE FENDER CHASSIS GROUND
"CHECK ENGINE"
MALFUNCTION
I/P CONNECTOR INDICATOR LAMP
METER (BLUE)
("";:; TO - BLK!YEL ~(---VEL~(;-VLT IGNITION 7.5A SWITCH
BLK ~ GRN MAIN RELAY
SOCKETEND SPLICES
TO ECM TERM. "D1" ECM SYSTEM GROUND
DATA
LINK CONNECTOR(WHITE)
1/P CONNECTOR
(WHITE)
BA TIERY VOLTAGE INPUT
IGNITION
VOLTAGE INPUT
"CHECK ENGINE"
MALFUNCTION
INDICATOR
LAMP DRIVER
~
DIAGNOSTIC REQUEST INPUT
' VIEW Fig. 6E2-24
./ .................................... __________________________ _

DRIVEABILITV AND EMISSIONS 6E2-39
CHART A-1
WILL NOT FLASH DIAGNOSTIC TROUBLE CODE (DTC) 12
NO 11CHECK ENGINE" MALFUNCTION INDICATOR LAMP (MIL)
CD • IGNITION "OFF".
• DISCONNECT ENGINE CONTROL MODULE (ECM) CONNECTORS.
• IGNITION "ON". • PROBE ECM TERMINAL "A5" WITH TEST LIGHT TO GROUND. IS THE "CHECK ENGINE" MALFUNCTION INDICATOR LAMP "ON"?
FAULTY ECM CONNECTION OR ECM. CHECK:
- METER FUSE. FAUL TV BULB. OPEN IN THE VL T
-WIRE. -OPEN IGNITION FEED TO BULB.
@ • IGNITION "OFF".
®
• DISCONNECT ECM CONNECTORS.
• IGNITION "ON".
• PROBE
ECM TERMINAL "C16", "B1" & "A6" WITH TEST LIGHT
TO GROUND. IS THE LIGHT "ON" FOR ALL THREE (3) CIRCUITS?
REPAIR OPEN IN CIRCUIT
THAT DID NOT LIGHT THE TEST LIGHT. IF A FUSIBLE
LINK OR FUSE WAS BLOWN, LOCATE AND CORRECT THE SHORT TO
GROUND ON THAT CIRCUIT.

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.

6E2-58 DRIVEABILITY AND EMISSIONS
Circuit Description:
DIAGNOSTIC TROUBLE CODE (DTC) 13
HEATED OXYGEN SENSOR (H02S) CIRCUIT
(OPEN/GROUNDED CIRCUIT)
The engine control module supplies a voltage of about .45 volt between terminals "83" and "82". (If measured
with a
10 megohm digital voltmeter, this may read as low as .32 volt).
When the Heated Oxygen Sensor (H02S) reaches operating temperature, it varies this voltage from about .1 volt
(exhaust is lean) to about .9 volt (exhaust is rich). The H02S has a heater incorporated as part of the sensor.
This heater is used to
heatthe sensor up, thus causing the H02S to produce voltage sooner. The heater portion of
the sensor
will not affect Diagnostic Trouble Code (DTC) 13 setting.
The sensor
is like an open circuit and produces no voltage, when it is below 3oo·c (572.F). An open sensor circuit,
or could sensor, cause "Open Loop" operation.
Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
• Engine operating temperature above 69SC (157.1.F).
• At least 3 minutes have elapsed since engine start-up.
• Oxygen signal voltage is steady between .347 and .547 volt.
• Throttle angle
above 9.8%.
• No DTC 21 or 31 is set.
• All above conditions are met for about 40 seconds.
If the conditions for a DTC 13 exist, the system will not go "Closed Loop."
® This test determines if the H02S is the problem or if the engine control module and wiring are at fault.
@ Use only a 10 megohm digital meter when performing this test. This test checks the continuity of "83" and
"82". If "82" is open, the engine control module voltage on "83" will be over .6 volt (600 mV).
Diagnostic Aids:
Normal "Scan tool" H02S voltage varies between 1 OOmv to 999 mv (.1 and 1.0 volt), while in "Closed Loop". DTC
13 sets in 40 seconds, if sensor signal voltage remains between 0.347 and 0.547 volt, but the system will go "Open
Loop"
in about 15 seconds.
Verify a
clean, tight ground connection for "82" at the engine mounting point. Open "83" or "82" will result in a DTC
13. If DTC 13 is intermittent, refer to "Symptoms", Section "6E2-8".
TRANSMISSION
HARNESS BLK CONNECTOR r 1
TRANSMISSION
HARNESS CONNECTOR
(BLUE) I /'< r--BLK/GRN ~~,---.,------«----BLU
RED/BLU (MIT) --« ! « RED
(BLUE) ~
PASSENGER Q SIDE
L T BLU (A/T) L
WHT/RED 1
P=H=~ r BLK/GRN ---.---BLK!GRN
BLK!YEL BLK!BLU FENDER
02 -----·'$ HEATER ELEMENT
02
l
ENGINE
BLOCK
TRANSMISSION HARNESS
-CONNECTOR (BLUE)
DRIVER'S SIDE REAR AT CYLINDER HEAD
SENSOR 10A TO
HEATER ---RED/GRN --• FUEL PUMP FUSE RELAY
Fig. 6E2-34
ENGINE CONTROL
MODULE(ECM)
H02S GROUND REFERENCE
H02S SIGNAL
ECM GROUNDS
ECM GROUNDS
•

FUEL SYSTEM
• CHECK:
• CHECK:
• CHECK:
• CHECK:
• CHECK:
• CHECK:
Fuel pump relay operation-pump should
turn "ON" for 2 seconds when ignition is
turned
"ON". Use CHART A-5.
Fuel injectors are correct for the vehicle.
Fuel
pressure, use CHART A-7.
Contaminated
fuel.
Engine fuse (visual inspect).
A
faulty in-tank fuel pump check valve will
allow
the fuel in the lines to drain back to
the tank after engine is stopped. To check
for this condition, perform fuel system
diagnosis CHART A-7.
IGNITION SYSTEM
• CHECK: For proper ignition voltage output with
spark tester J26792 or equivalent (ST-
125).
DRIVEABILITY AND EMISSIONS 6E2-91
• CHECK: Spark plugs. Remove spark plugs, check
for wet plugs, cracks, wear, improper
gap, burned electrodes, or heavy
deposits. Repair
or replace as necessary.
• CHECK: Bare or shorted wires.
• CHECK: Loose ignition coil ground.
ADDITIONAL CHECKS
• CHECK: Idle air control operation-use CHART C-
2C.
• CHECK: Basic engine problem. Refer to ENGINE
MECHANICAL DIAGNOSIS (SECTION
6A).
• CHECK: Service Bulletins for calibration updates.
SURGES AND/OR CHUGGLES
Definition: Engine power variation under steady
throttle or cruise. Feels like the car speeds
up and
slows down with no change in the
acceleration pedal.
PRELIMINARY CHECKS
• Perform the careful visual checks as described at
start
of "Symptoms," Section "6E2-B."
•
Be sure driver understands transmission
operation, and air conditioning compressor
operation
as explained in the owner's manual.
SENSORS
• CHECK: Heated oxygen sensor (H02S). The
H02S should respond quickly to different
throttle position, if it does not, check the
H02S for silicon or other contaminations
from fuel, or use of improper RTV sealant.
The sensor may have a white, powdery
coating and result in a high but false
signal voltage
(rich heated H02S signal
indication). The engine control module
will
then reduce the amount of fuel
delivered
to the engine, causing a severe
driveability problem. Also, watch for
green glycol contamination or cracking.
FUEL SYSTEM
• NOTICE: To determine ifthe condition is caused by
a rich
or lean system, the car should be
driven at the speed of the complaint.
Monitoring block learn will help identify a
problem.
Lean -Block learn above 142. Refer to
"Diagnostic Aids" on facing page of
diagnostic trouble code 44.
Rich -L.T. Fuel Trim above 118. Refer to
"Diagnostic Aids" on facing page of
diagnostic trouble code 45.
• CHECK: Fuel pressure while condition exists. Use
CHART A-7.
• CHECK: In-line fuel filter. Replace if dirty or
plugged.
IGNITION SYSTEM
• CHECK: For proper ignition voltage output using
spark tester (ST-125) J26792
or
equivalent .
• CHECK: Spark plugs. Remove spark plugs, check
for wet plugs, cracks, wear, improper
gap, burned electrodes, or heavy
deposits. Repair
or replace as necessary.
Also, check condition of electronic
ignition and spark plug wires.
• CHECK: Ignition timing. Using "Scan tool".
ADDITIONAL CHECKS
• CHECK: Engine control module grounds for being
clean, tight and in their proper location.
• CHECK: Vacuum lines for kinks or leaks.
• CHECK: Exhaust gas recirculation -There should
be no exhaust gas recirculation at idle.
Refer to CHART C-7.
• CHECK: Generator output voltage. Repair if less
than 9 or more than 16 volts.