check engine ISUZU TROOPER 1995 Workshop Manual

6E2-26 DRIVEABILITV AND EMISSIONS
ENGINE CONTROL MODULE WIRING DIAGRAM (1) (SOHC}
To ignition
switch 10 A
Meter fuse Underhood
connectors
located driver's side
shock tower
"Check Engine" MALFUNCTION
.-----------..:.:.1 N.:.:D:..:.IC=A~T~O:..:.R.:....=:.LA..::.M.:..::P:..___-,--___.:O:..:.R.:.:.N::.._IY.....:E:..:L=----1 c4
.------~~----~~O:..:R:..:N/~8~L=-=K--~ C 2
TCM
(C91-C8)
Engine Control Module(ECM)
"Check
engine" light control
DLC Diagnostic Request Input
Serial
data inpuVoutput
.--------f---+-....::...::;_;__=---_-1 A 12 System ground
Common
Data Link Connector (White) Chamber L.....::.=::....=..:=-=----+---1 C12 System ground
Intake air
temperature sensor
Throttle position
sensor
Manifold absolute pressure sensor
Engine
Coolant Temperature sensor Heated
oxygen
J-,.:..:W:.:..H.:..:T.:.:I8:..:L:.:U:......__ __ ....-To Fuel
RED/BLU (M/T)
1---=-'L T'-.!8~L:!:U'--l(.::::A/T!....!...!....) ---< f------lt+-~!,!..._'H---1 83
BRN/8LK
84
8RN/WHT 85
BRN/RED 87
8RN!YEL
BS
1---------~~~B~L~U~/8~L~K~--I 07
BLK/WHT
TCM
(C91-C6)
BLK/WHT 1------------4>---< t-----=~:..:.:..:_.:..:_ ....... -1 02
1-----------~ f----'-=-'-==--....-1 06
1-----------~ f--.-::..:=.=.:....=..c~-+--1 A 1
BLU/ORN
H02S Signal Input
H02S Ground
lAC coil "A" HI
lAC coil "A" LO
lAC coil "B" HI
lAC coil "B" LO
IAC=IDLE AIR CONTROL
Intake
Air Temperature(IAT)
signal input
Sensor ground
TPS signal input
5 volt reference
MAP
signal input
1---------'----...._.G:=.:..:.RY-=--------1 A 11 Sensor ground
1-------;---.:::G:..:R_;_YI:...::8:..:L::..:K:__---I 012 Engine Coolant Temperature
signal input
Fig. 6E2-17
•

DRIVEABILITY AND EMISSIONS 6E2-29
ENGINE CONTROL MODULE WIRING DIAGRAM (1) (DOHC)
Underhood connectors
located driver's side
shock
tower
To ignition
switch 7.5AMP ,.... ~ ®
I
I
Meter fuse I "Check Engine" I Malfunction I Indicator Lamp I
I
'
I 8LK/8LU I
D
I l TCM (C91-C8) 1
~ 1 2 ~ ~ co.;;mo~~ : ata Link Connector (White) Chamber 1 0 Common1 Chamber 1 Heated oxygen -= I
rg
=F
leair s ontrol C] alve
ld c v
M
te anifold
air
mperature sensor
Throttle position sensor
Manifold absolute pressure sensor
Engine
Coolant
T emperature
Sensor
sensor I
I
-A/IN-1:'1 WHT/8LU I
~ RED/8LU (M/TI I
~ ""21 L T 8LU (A/TI II ....::....1 ,1,
8LK/GRN :,
I
I
I
I
cam l:
I
I
Au A )I y"-\1 r--
8 8LK/WHT I I
I
I
I
8 ~ 1--II
~ r£ \ 'I A ,1,
8LU/ORN I
r£ ~ I
8 ~ f--I A I
I
I
_A& a A I y"-I r--I 8 I
I
I
Fig. 6E2-20
VLT
ORNNEL
ORN/8LK
8LK/8LU
I 8LK/8LU
To Fuel
pump relay
( ) RED ( v v
8LU
~ -8RN/8LK
8RN/WHT
8RN/RED
8RNNEL
8LU/8LK
TCM (C91-C6)
8LK/WHT !
RED/8LU
8LU/ORN
TCtM
(C91-C5)
GRY/RED
GRY
GRY/8LK Engine
Control
Module (ECMI
.-----
AS "Check engine" light control
C4 DLC Diagnostic Request lnpu
C2 Serial data input/output
A12 System ground
C12 System ground
83
H02S Signal input
82 H02S ground
84
lAC coil "A" HI
85 lAC coil "A" LO
87 lAC coil "8" HI
86 lAC coil "8" LO
lAC = Idle Air Control
D7 MAT signal input
D2 Sensor ground
D6 TPS signal input
A1 5 volt reference
D9 MAP signal input
A11 Sensor ground
D12 Engine Coolant Temperatur e signal input
......__

DRIVEABILITY AND EMISSIONS 6E2-33
ENGINE CONTROL MODULE (ECM) CONNECTOR IDENTIFICATION
This engine control module voltage chart is for use with a digital voltmeter to further aid in diagnosis. The voltages
you get may vary due to low battery charge or other reasons, but they should be very close.
The following conditions must be before testing:
• Engine at operating temperature • "Scan tool" not installed
•
Engine idling in "Close Loop" (for "Engine Run"
column) •
All voltages showing "Battery Position Voltage
(8+)" indicates battery or charging voltage
•
DLC Diagnostic terminal not grounded
VOLTAGE VOLTAGE
DC CIRCUIT PIN WIRE
KEY ENG. COLOR
"ON" RUN
DC CIRCUIT PIN WIRE
KEY ENG. COLOR "ON" RUN
ID 5.0V 5.0V THROTILE
POSITION ~TP~ SENSOR & MANIFOLD ABSOLUT P ESSURE A1 BLU/ORN 8+ B+ BATIERY FEED B1 RED/WHT
5 VOLT REFERENCE B+"ON" B+ OFF AIR CONDITIONING CLUTCH RELAY A2 GRY/YEL 0 "OFF" 0* ON
CONTROL o• o• OXYGEN SIGNAL GROUND 82 BLU
B+ s+ INTAKE
AIR VACUUM SWITCH VALVE A3 WHT/BLU (VSV) CONTROL
o• O*® SHIFT INDICATOR LAMP DRIVER A4 ORN/BLU .430MV
VALlES OXYGEN
SIGNAL INPUT
B3 RED
NOT NOT
IDLE AIR CONTROL (lAC) COIL "A" HI B4 8RN/BLK USABLE
USABLE
o• B+ "CHECK ENGINE" MALFUNCTION A5 VLT INDICATOR LAMP CONTROL
B+ B+ IGNITION VOLTAGE SIGNAL INPUT
AS RED/GRN
NOT NOT
lAC COIL "A" LO B5 8RN/WHT USABLE USABLE
NOT NOT
lAC COIL
"B" LO B6 BRN/YEL USABLE
USABLE
B+ B+ EVAPORATE EMISSION CANISTER PURGE A7 WHT/RED VSVCONTROL NOT
NOT
lAC COIL "B" HI B7 BRN/RED USABLE
USABLE
B+ 8~ EXHAUST GAS RECIRCULATION AS WHT/GRN VSV CONTROL
@VAR VAR TRANS TP SENSOR SIGNAL OUTPUT A9 8RN
o• o• ELECTRONIC IGNITION REFERENCE LO 88 YEL/BLK
o• 1.1V-ELECTRONIC
IGNITION REFERENCE HI B9 YEL/RED
2.4V
NOT USED B10
NOT USED
A10
NOT USED
B11 o• o• SENSOR GROUND A11 GRY
NOT USED B12 GRY/BLU o• o• SYSTEM
GROUND A12 8LK/PNK
VOLTAGE
VOLTAGE
DC CIRCUIT PIN WIRE
KEY ENG. COLOR DC CIRCUIT PIN WIRE
KEY ENG. COLOR "ON" RUN "ON" RUN
NOT USED C1 o• o• SYSTEM GROUND D1 BLK/BLU
4.7V 4.7V
SERIAL DATA INPUT/OUTPUT C2 ORN/8LK o• 0* SENSOR GROUND D2 BLK/WHT
@) B+ B+ FUEL PUMP RELAY CONTROL C3 PNK/WHT NOT USED D3
B+ B+ DLC DIAGNOSTIC REQUEST INPUT C4 ORN/YEL NOT USED D4
NOT USED C5 o• .1·.2V IGNITION
CONTROL OUTPUT D5 YEL
@B+ B+ POWER STEERING PRESSURE SWITCH C6 GRN/YEL SIGNAL INPUT 0.54V VAR
TP SENSOR
SIGNAL INPUT D6 BLU/RED
@O* o• PARK/NEUTRAL POSITION
INPUT C7 BLU/PNK VAR
VAR INTAKE AIR TEMPERATURE SIGNAL D7 BLU/BLK INPUT D7 BLU/BLK
NOT USED CB ® ® VEHICLE SPEED SENSOR
SIGNAL INPUT D8 WHT/BLK
B+"ON" 0 "ON" AIR CONDITIONING REQUEST SIGNAL C9 GRN/ORN
0 "OFF" B+"OFF"
INPUT 4.7V 1-2V MANIFOLD ABSOLUTE PRESSURE D9 GRY/RED SIGNAL
INPUT
NOT USED
C10 8-10V
VAR K.S.
MODULE INPUT D10 LTGRN/WHT
B+ B+ FUEL INJECTOR
DRIVER C11 BLU/YEL o• 4.9V IGNITION CONTROL BYPASS CONTROL D11 YELIGRN
o• o• SYSTEM GROUND
C12 BLK/PNK VAR VAR ENGINE COOLANT TEMPERATURE
D12 GRY/BLK SIGNAL
INPUT
NOT USED
C13 NOT USED D13
B+ 8+
FUEL INJECTOR DRIVER C14 BLU/GRN NOT USED D14
o• o• SYSTEM GROUND
C15 BLK/BLU B+ B+ FUEL INJECTOR DRIVER D15 ORN/BLU
8+ B+ BATIERY FEED C16 RED/WHT B+ 8+
FUEL INJECTOR DRIVER D16 ORN/8LU
* All voltages shown "0" should read less than .5 volts.
Reads battery positive voltage for 2 seconds after ignition "ON" then should read 0 volts. CD
®
® @
B+ with shifter in gear and clutch pedal not depressed.
B+ to 0 volts depending on Position of drive wheels
B+ for 2 seconds.
@
®
0 Volt with steering wheel cramped.
A/T Vehicles only

6E2-34 DRIVEABILITY AND EMISSIONS
''SCAN TOOL" ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK
The Diagnostic Circuit is an organized approach to identifying a problem created by an electronic engine control
system malfunction. It must be the starting point for any drive ability complaint diagnosis, because it directs the
service technician to the next
logical step in diagnosing the complaint.
The "Scan tool" data listed in the table may be used for comparison, after completing the on-board diagnostic
system check and finding the on-board diagnostics functioning
properly with no trouble codes displayed. The
"Typical Data Values" are an average of display values recorded from normally operating vehicles and are
intended
to represent what a normally functioning system would typically display.
A "SCAN tool" that displays faulty data should not be used, and the problem should be reported to the
manufacturer. The use of a faulty "SCAN tool" can result in misdiagnosis and unnecessary parts
replacement.
Only the parameters listed below are used in this manual for diagnosis. If a "Scan tool" reads other parameters,
the
values are not recommended for use in diagnosis. For more description on the values and use of the "Scan
tool" to diagnosis engine control module inputs, refer to the applicable component diagnosis section in
"Component System", Section "6E2-C". If all values are within the range illustrated, refer to "Symptoms", Section
"6E2-B".
"SCAN TOOL" DATA
Test under following condition.
Idle I Upper radiator hose hot I Closed throttle I Park or neutral I "Closed Loop" I All Accessories "OFF"
"SCAN TOOL" position Units displayed Typical data value
Engine Speed RPM ± 50 RPM from desired RPM in drive (A/T) ± 100 RPM from desired rpm in neutral (MIT)
Desired
RPM RPM Engine control module idle command (varies with Engine load and temperature)
ENG COOL TEMP
Degrees Celsius/Fahrenheit 85-105 (185-221)
Intake Air Temperature (IAT) Degrees Celsius/Fahrenheit 10-90 (50-199) (varies with Underhood
temperature and sensor location)
Manifold Absolute Pressure Volts 1 - 2 (varies with manifold and barometric pressure)
Barometric Pressure Volts Varies depending on altitude
Throttle Position Volts .50-1.25
Throttle Angle 0-100% 0 at Idle
BPW (base pulse width) Milliseconds 0.0 to 499.9
Oxygen Sensor Volts Volts .1 - 1 (varies continuously)
S.T. Fuel
Trim Counts 108-154
LT. Fuel Trim Counts 116-145
Loop Status
Open/Closed "Closed Loop"
Fuel Trim Cell 0/1 1
Spark Advance Degrees Varies continuously
Ignition Control Enable No/Yes Yes
Knock Retard
Degrees
0-45
Shift Light OFF/ON OFF
Idle Air Control
Counts (steps) 1 -50 depending on engine load
PARK/NEUTRAL P-N and R-D-L Park/Neutral (AUTO)
A/C Request Switch Yes/No No
A/C Request ON/OFF "OFF"
Vehicle Speed
Mile per hour/KPH 0
Power Steering
NORMAL/HI PRESSURE NORMAL
EGR Solenoid
ON/OFF OFF
AIR Control Solenoid
ON/OFF OFF
Induction Air Solenoid OFF/ON OFF ("ON" above 5000 RPM)
Air Fuel Ratio Ratio 0-25.5:1
EVAP Purge OFF/ON OFF
Idle Throttle No/Yes Yes
Fuel Trim Enable No/Yes Yes
System Voltage Volts 13-15
PROM ID 000 0-65535
Time From Start 00:00

6E2-36 DRIVEABILITV AND EMISSIONS
ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK
The on-board diagnostic system check is an organized approach to identifying a problem created by an Electronic
Engine
Control System malfunction. It must be the starting point for any driveability complaint diagnosis, because
it directs the service technician to the next logical step in diagnosing the complaint. Understanding the chart and
using
it correclty will reduce diagnostic time and prevent the unnecessary replacement of good parts.
Test Description:
Number(s) below refer to circled number(s) on the following diagnostic chart.
CD This check is to see if the Engine Control Module (ECM) can provide a ground path for the "Check Engine"
malfunction indicator lamp, this is a bulb check. If it can do this, it confirms that the ECM has power, ground
and is capable
of some functions. If the malfunction indicator lamp is "OFF", Chart A-1 will check for both
ignition feed and constant battery power to the
ECM and the ECM grounds.
® This check is done to see if the ECM has the capability of performing internal diagnostics. Diagnostic trouble
code
12 means there is no crankshaft position coming to the ECM, this is normal because the engine is not
running.
® This check is used to see if the ECM can supply serial data for Tech 1 "Scan tool" use.
@ Look at all the parameters to determine if on is not in a normal state with just the ignition "ON" and engine
"OFF". In particular, look at the barometric pressure reading from the MAP sensor voltage and kPa values.
Are they normal for
your altitude? If not, use Chart C1-D. Look at the Engine Coolant Temperature (ECT)
Sensor value to see if the value is shifted above or below where it should be. If so, see diagnostic aid chart on
Diagnostic Trouble
Code 14 chart.
@ This test is used to see if the cause of a "No-Start" is because of an ECM problem or the vehicle electrical
system.
® This check is to see ifthe ECM has any diagnostic codes stored in it memory to aid in diagnosing the customer
complaint.
TO FUEL
PUMP
RELAY 15A
,------------+--RED/WHT Engine
Control Module(ECM)
BATTERY
VOLTAGE INPUT
ECM FUSIBLE L_ __ RED/WHT
~~TTERY LINK 30A ~
VOLTAGE ..,.,.f----BLK/RED
TO
~t-----tr-RED/WHT -----,t--+---.-RED/GRN
IGNITION BLK/YEL J-------BLK/YEL -TCM BLK
SWITCH
TO EGR VALVE VSV
CANISTER PURGE VSV SECONDARYINTAKEVSV REED VALVE VSV
TO FUEL (C91-C8)
INJECTORS RED/GRN
TO KS MODULE ..,._ ___ RED/GRN
LOCATED
PASSENGER
SIDE
FENDER CHASSIS
GROUND
"CHECK ENGINE" MALFUNCTION
I/P CONNECTOR INDICATOR LAMP
METER (BLUE)
f'7:' TO ..,._ __ BLK/YEL ~~VEL~(;-VLT IGNITION
SWITCH 7.5A
SPLICES TO
ECM TERM. "D1" ECM SYSTEM
GROUND
DATA LINK CONNECTOR(WHITE)
Fig. 6E2-23a
1/P CONNECTOR
(WHITE)
BATTERY VOLTAGE INPUT
IGNITION
VOLTAGE INPUT
"CHECK ENGINE"
MALFUNCTION
INDICATOR
LAMP DRIVER
-=:J._
DIAGNOSTIC
REQUEST INPUT
•

DRIVEABILITY AND EMISSIONS 6E2-37
ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK
(j) • IGNITION "ON" ENGINE "OFF".
• NOTE "CHECK ENGINE" MALFUNCTION INDICATOR LAMP.
STEADY LIGHT
@ • JUMPER DATA LINK CONNECTOR TERM. "1" TO "3".
• DOES MALFUNCTION INDICATOR LAMP FLASH DTC 127
@ DOES "SCAN TOOL" DISPLAY ENGINE CONTROL MODULE DATA?
REFER TO APPLICABLE DTC CHART. START WITH LOWEST DTC.
CHECK FOR GROUNDED DIAGNOSTIC TEST CKT. USE WIRING DIAGRAM ON CHART A-1.
@ COMPARE "SCAN TOOL" DATA WITH TYPICAL VALUES SHOWN ON FACING PAGE. ARE VALUES NORMAL OR WITHIN TYPICAL RANGES?
REFER TO INDICATED "COMPONENT(S) SYSTEM" CHECKS IN~·.

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.

6E2-40 DRIVEABILITY AND EMISSIONS
CHART A-2
NO DATA LINK CONNECTOR (DLC) DATA OR
WILL NOT FLASH DIAGNOSTIC TROUBLE CODE (DTC) 12
"CHECK ENGINE" MALFUNCTION INDICATOR LAMP (MIL) "ON" STEADY
Circuit Description:
There should always be a steady "Check Engine" malfunction indicator lamp when the ignition is "ON" and engine
stopped. Battery positive
voltage is supplied directly to the light bulb. The Engine Control Module (ECM) will turn
the
light "ON" by grounding VLT wire at the ECM.
With the diagnostic test terminal grounded, the light should flash a diagnostic trouble code (DTC) 12, followed by
any trouble code(s) stored in memory.
A steady
light suggests a short to ground in the light control VLT wire, or an open in diagnostic ORNIYEL wire.
Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
CD If there is a problem with the ECM that causes a "Scan tool" to not read Serial data, then the ECM should not
flash a DTC 12.1f DTC 12 does flash, be sure that the "Scan tool" is working properly on anothervehicle.lfthe
"Scan tool" is functioning properly and ORN/BLK wire is OK, the ECM, may be at fault for the NO data link
connector symptom.
@ If the light goes "OFF" when the ECM connector is disconnected, then, the VLTwire is not shorted to ground.
® This step will check for an open diagnostic request ORN/YEL wire.
® At this point, the "Check Engine" malfunction indicator lamp wiring is OK. The problem is a faulty ECM.IfDTC
12 does not flash, the ECM should be replaced.
TO FUEL PUMP
FUEL RED/BLK ENGINE CONTROL MODULE(ECM)
PUMP 15A
RELAY
,.-------------.--RED/WHT
TO BATTERY
ECM FUSIBLE
LINK 30A
VOLTAGE
...,. .. 1---BLK!RED
TO IGNITION
SWITCH ENGINE
15A
'------RED/WHT
BLK
BLK!YEL
~ BLK!YEL
TO EGA VALVE VSV TO FUEL CANISTER PURGE VSV INJECTORS ..._ ___ RED/GRN
LOCATED
PASSENGER
SIDE
FENDER CHASSIS
GROUND
SECONDARY
INTAKE VSV TO KS ..._ ___ RED/GRN REED VALVE VSV MODULE
"CHECK ENGINE"
MALFUNCTION
liP CONNECTOR INDICATOR
LAMP
METER (BLUE)
f'7:'
TO -----BLK!YEL ~~ YEL ---\C:;J- SWITCH
BLK
GRN
MAIN RELAY SOCKET END VIEW
7.5A
SPLICES TO ECM TERM. "D1" ECM SYSTEM
GROUND
DATA LINK CONNECTOR
(WHITE)
Fig. 6E2-25
I/P CONNECTOR
(WHITE)
BATTERY VOLTAGE
INPUT
BATTERY VOLTAGE
INPUT
IGNITION
VOLTAGE INPUT
"CHECK ENGINE"
MALFUNCTION
INDICATOR
LAMP DRIVER
~
DIAGNOSTIC
REQUEST INPUT

®
.... /"{ rtS (ill .. , (. --f (.'' \J DRIVEABILITV AND EMISSIONS 6E2-41
CHART A-2
NO DATA LINK CONNECTOR (DLC) DATA OR
WILL NOT FLASH DIAGNOSTIC TROUBLE CODE (DTC) 12
"CHECK ENGINE" MALFUNCTION INDICATOR LAMP (MIL) "ON" STEADY
• IGNITION "ON", ENGINE "OFF". IS THE "CHECK ENGINE" MALFUNCTION INDICATOR LAMP (MIL) "ON"?
~ $
• GROUND DATA LINK CONNECTOR, DIAGNOSTIC USE CHART A-1 I TERMINAL "1" AND "3". DOES LIGHT FLASH DIAGNOSTIC TROUBLE CODE (DTC) 12?
$ $
• IGNITION "OFF". G) IF PROBLEM WAS NO DATA LINK CONNECTOR
• DISCONNECT ENGINE CONTROL MODULE (ECM) DATA: CHECK SERIAL DATA CIRCUIT FOR OPEN OR CONNECTORS.
SHORT TO GROUND BETWEEN ECM AND DATA • IGNITION "ON" AND NOTE MIL LINK CONNECTOR. IF OK, IT IS A FAULTY ECM.
I LIGHT "OFF" I LIGHT "ON" j
I • IGNITION "OFF". REPAIR SHORT TO GROUND IN MIL CIRCUIT.
• RECONNECT ECM.
• IGNITION "ON", ENGINE "OFF",
DIAGNOSTIC TEST TERMINAL NOT GROUNDED.
• BACK
PROBE ECM TERMINAL "C4" WITH TEST
LIGHT TO GROUND.
LEAVE CONNECTED AND WATCH MIL.
I NO DTC 12 I DTC 12 I
I REPLACE ECM I CHECK FOR OPEN IN ORNIYEL WIRE. IF OK, CHECK FOR OPEN CIRCUIT BETWEEN DATA LINK CONNECTOR TERMINAL "3" AND GROUND.
CLEAR DTC(S) AND CONFIRM "CLOSED LOOP" OPERATION AND NORMAL"CHECK ENGINE" MALFUNCTION INDICATOR LAMP OPERATION.