engine coolant ISUZU TF SERIES 2004 Workshop Manual

6E-122 3.5L ENGINE DRIVEABILITY AND EMISSIONS
A/C SYSTEM CIRCUIT DIAGNOSIS



RTW36EMF000101

CIRCUIT DESCRIPTION
When air conditioning and blower fan are selected, and
if the system has a sufficient refrigerant charge, a
12-volt signal is supplied to the A/C request input of the
Engine Control Module (ECM). The A/C request signal
may be temporarily canceled during system operation
by the electronic thermostat in the evaporator case. The
electronic thermostat may intermittently remove the
control circuit ground for the A/C thermostat relay to
prevent the evaporator from forming ice. When the A/C
request signal is received by the ECM, the ECM
supplies a ground from the compressor clutch relay i
f
the engine operating conditions are within acceptable
ranges. With the A/C compressor relay energized,
voltage is supplied to the compressor clutch coil.
The ECM will enable the compressor clutch to engage
whenever A/C has been selected with the engine
running, unless any of the following conditions are
present:

 The A/C request switch is "Off".
 The engine speed is lower than 550rpm or greate
r
than 6375rpm.
 The engine coolant temperature is greater than
120
.
DIAGNOSTIC AIDS
To diagnose an the intermittent fault, check for the
following conditions:
 Poor connection at the ECM–Inspect connections fo
r
backed-out terminals, improper mating, broken locks,
improperly formed or damaged terminals, and poo
r
terminal-to-wire connection.
 Damaged harness–Inspect the wiring harness fo
r
damage. If the harness appears to OK, observe the
A/C clutch while moving connectors and wiring
harnesses related to the A/C. A sudden clutch
malfunction will indicate the source of the intermitten
t
fault.

6E-132 3.5L ENGINE DRIVEABILITY AND EMISSIONS Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure Parts Related
ECM Pin
No. Related
Multiple
DTC
P0117 A Engine Coolant Temperature
Sensor Low Input ECT sensor output voltage is below 0.08V. ECT sensor output voltage is
more than 0.08V. 1. Sensor signal circuit short to ground circuit.
2. ECT sensor malfunction.
3. ECM malfunction. A21 -
14
P0118 A Engine Coolant Temperature
Sensor High Input ECT sensor output voltage is more than 4.8V. The ECM uses default engine
coolant temperature value
based on start-up ECT and
time from start.
ECT sensor output voltage is
below 4.8V. 1. Sensor signal circuit open or short to voltage
circuit.
2. Sensor ground circuit open or short to voltage
circuit.
3. Poor connector connection
4. ECT sensor malfunction.
5. ECM malfunction. A21/
A22 P0406
1. No DTC relating to barometer sensor, ECT
sensor, CMP sensor, CKP sensor, MAF
sensor and TPS (low input & high input).
2. Engine speed is more than 2000rpm.
3. Engine coolant temperature is more than
75
C.
4. TPS output voltage is between 0.24V and
0.26V. Above conditions are met for 3
seconds.
OR
P0121 A Throttle Position Sensor
Range/Performance
1. No DTC relating to barometer sensor, ECT
sensor, CMP sensor, CKP sensor, MAF
sensor and TPS (low input & high input).
2. Engine speed is below 3200rpm.
3. Engine coolant temperature is more than
75
C.
4. TPS output voltage is between 4.54V and
4.56V. Above conditions are met for 3
seconds. No fail-safe function. TPS output voltage is below
0.24V or more than 0.26V.
OR
TPS output voltage is below
4.54V or more than 4.56V. 1. TPS malfunction.
2. Sensor signal circuit short to voltage circuit.
3. Electrical interference.
4. ECM malfunction. B27/
B26/
B39 - P0122 A Throttle Position Sensor Low
Input TPS output voltage is below 0.24V. TPS output voltage is more
than 0.24V. 1. Sensor power supply circuit open or short to
ground circuit.
2. Sensor signal circuit open or short to ground
circuit.
3. Poor connector connection.
4. TPS malfunction.
5. ECM malfunction. B27/
B26 P0336/
P0337
or
P0342
21
P0123 A Throttle Position Sensor High
Input TPS output voltage is more than 4.56V. The ECM uses default throttle
position value based on mass
air flow and engine speed.
TPS output voltage is below
4.56V. 1. Sensor power supply circuit short to voltage
circuit.
2. Sensor signal circuit short to voltage circuit.
3. Sensor ground circuit open or short to voltage
circuit.
4. Poor connector connection.
5. TPS malfunction.
6. ECM malfunction. B27/
B26/
B39 P0103/
P0113/
P0341/
P0342

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-133
Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure Parts Related
ECM Pin
No. Related
Multiple
DTC
P0131 A O2 Sensor Circuit Low Voltage
(Bank 1 Sensor 1) B21/
B22 P0171/
P1171/
P1172 P0151 A O2 Sensor Circuit Low Voltage
(Bank 2 Sensor 1) 1. No DTC relating to ECT sensor, CMP sensor,
CKP sensor, VSS, injector control circuit,
ignition control circuit and O2 sensor circuit no
activity (bank 1 & 2).
2. Engine speed is between 1000rpm and
4000rpm.
3. Engine coolant temperature is between 70
C
and 110
C.
4. Vehicle speed is between 0km/h and
120km/h.
5. Engine load is between 80% and 160%.
6. Throttle position fluctuation is below 0.28V.
7. O2 sensor bank 1 or bank 2 output voltage is
more than 400mV for 50 seconds. "Open Loop" fuel control. O2 sensor bank 1 or bank 2
output voltage is below 400mV
for 50 seconds. 1. Sensor harness open or short to ground
circuit.
2. O2 sensor malfunction.
3. MAF sensor output is incorrect.
4. Air intake line malfunction.
5. IAC valve malfunction.
6. Low fuel pressure.
7. Injector malfunction.
8. ECM malfunction.
B23/
B24 P0174/
P1171/
P1172 P0132 A O2 Sensor Circuit High Voltage
(Bank 1 Sensor 1) B21/
B22 P0172 P0152 A O2 Sensor Circuit High Voltage
(Bank 2 Sensor 1) 1. No DTC relating to ECT sensor, CMP sensor,
CKP sensor, VSS, injector control circuit,
ignition control circuit and O2 sensor circuit no
activity (bank 1 & 2).
2. Engine speed is between 1000rpm and
4000rpm.
3. Engine coolant temperature is between 70
C
and 110
C.
4. Vehicle speed is between 0km/h and
120km/h.
5. Engine load is between 80% and 160%.
6. Throttle position fluctuation is below 0.28V.
7. O2 sensor bank 1 or bank 2 output voltage is
below 600mV for 50 seconds. "Open Loop" fuel control. O2 sensor bank 1 or bank 2
output voltage is more than
600mV for 50 seconds. 1. Sensor harness open or short to ground
circuit.
2. O2 sensor malfunction.
3. MAF sensor output is incorrect.
4. Air intake line malfunction.
5. AC valve malfunction.
6. Low fuel pressure.
7. Injector malfunction.
8. EVAP purge solenoid valve malfunction.
9. Ignition system malfunction.
10. Spark plug malfunction.
11. ECM malfunction. B23/
B24 P0175 P0134 A O2 Sensor Circuit No Activity
Detected (Bank 1 Sensor 1) B21/
B22 -
15

P0154 A O2 Sensor Circuit No Activity
Detected (Bank 2 Sensor 1) 1.No DTC relating to MAF sensor, ECT sensor,
CMP sensor, CKP sensor, VSS, injector
control circuit and ignition control circuit.
2. Engine coolant temperature is more than
70
C.
3. Vehicle speed is more than 60km/h.
4. O2 sensor bank 1 or bank 2 output voltage is
between 350mV and 600mV. "Open Loop" fuel control. O2 sensor bank 1 or bank 2
output voltage is below 0.35mV
consecutively.
OR
O2 sensor bank 1 or bank 2
output voltage is more than
600mV consecutively. 1. O2 sensor malfunction.
2. ECM malfunction.
B23/
B24 -

6E-134 3.5L ENGINE DRIVEABILITY AND EMISSIONS Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure Parts Related
ECM Pin
No. Related
Multiple
DTC
P0171 B O2 Sensor System Too Lean
(Bank 1) - -
44
P0174 B O2 Sensor System Too Lean
(Bank 2) 1. No DTC relating to MAF sensor, IAT sensor,
ECT sensor, TPS, CMP sensor, CKP sensor,
VSS, injector control circuit, ignition control
circuit, O2 sensor circuit low voltage & high
voltage (bank 1 & 2) and O2 sensor circuit no
activity (bank 1 & 2).
2. Engine speed is more than 600rpm.
3. Intake air temperature is more than 50
C.
4. Engine coolant temperature is between 35
C
and 120
C.
5. Engine load is more than 20.
6. EVAP purge solenoid valve on-duty is below
100%.
7. Air-fuel ratio correction volume is more than
150% for 20 seconds. No fail-safe function. Air fuel ratio correction volume
is between 50% and 150% for
5 seconds. 1. Sensor harness open or short to ground
circuit.
2. O2 sensor malfunction.
3. MAF sensor output is incorrect.
4. Air intake line malfunction.
5. IAC valve malfunction.
6. Low fuel pressure.
7. Injector malfunction.
8. ECM malfunction.
- -
P0172 B O2 Sensor System Too Rich
(Bank 1) - -
45
P0175 B O2 Sensor System Too Rich
(Bank 2) 1. No DTC relating to MAF sensor, IAT sensor,
ECT sensor, TPS, CMP sensor, CKP sensor,
VSS, injector control circuit, ignition control
circuit, O2 sensor circuit low voltage & high
voltage (bank 1 & 2) and O2 sensor circuit no
activity (bank 1 & 2).
2. Engine speed is more than 600rpm.
3. Intake air temperature is more than 50
C.
4. Engine coolant temperature is between 35
C
and 120
C.
5. Engine load is more than 20.
6. EVAP purge solenoid valve on-duty is below
100%.
7. Air-fuel ratio correction volume is below 50%
for 20 seconds. No fail-safe function. Air fuel ratio correction volume
is between 50% and 150% for
5 seconds. 1. Sensor harness open or short to ground
circuit.
2. O2 sensor malfunction.
3. MAF sensor output is incorrect.
4. Air intake line malfunction.
5. AC valve malfunction.
6. Low fuel pressure.
7. Injector malfunction.
8. EVAP purge solenoid valve malfunction.
9. Ignition system malfunction.
10. Spark plug malfunction.
11. ECM malfunction. - -

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-135
Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure Parts Related
ECM Pin
No. Related
Multiple
DTC
P1171 D Fuel Supply System Lean
During Power Enrichment
(Bank 1) B21/
B22/
-
44
P1172 D Fuel Supply System Lean
During Power Enrichment
(Bank 2) 1. No DTC relating to MAF sensor, IAT sensor,
ECT sensor, TPS, CMP sensor, CKP sensor,
VSS, injector control circuit, ignition control
circuit, O2 sensor circuit low voltage & high
voltage (bank 1 & 2) and O2 sensor circuit no
activity (bank 1 & 2).
2. Engine speed is between 1000rpm and
6000rpm.
3. Intake air temperature is below 70
C.
4. Engine coolant temperature is between 30
C
and 120
C.
5. Engine load is between 150 and 255.
6. Throttle position output is more than 2.22V
and fluctuation is below 0.28V.
7. Except fuel cut operation.
8. O2 sensor output voltage below 250mV for 10
seconds. No fail-safe function.
O2 sensor output voltage is
more than 520mV for 5
seconds.
1. Sensor harness open or short to ground
circuit.
2. O2 sensor malfunction.
3. MAF sensor output is incorrect. 4. Air intake
line malfunction.
5. IAC valve malfunction.
6. Low fuel pressure.
7. Injector malfunction.
8. ECM malfunction.
B23/
B24 -
P0201 A Injector 1 Control Circuit
A36 - P0202 A Injector 2 Control Circuit
B3 - P0203 A Injector 3 Control Circuit
A35 - P0204 A Injector 4 Control Circuit
B4 - P0205 A Injector 5 Control Circuit
A34 -
31
P0206 A Injector 6 Control Circuit 1. No DTC relating to CMP sensor and CKP
sensor.
2. Under sequential injection.
3. Injection pulse is between 2.5ms and 7.5 ms.
4. Except fuel cut operation.
5. Engine speed is between 600rpm and
2000rpm.
6. 30 injection signals are not detected
consecutively. No fail-safe function. 30 injection signals are
detected consecutively. 1. Injector harness open circuit, short to ground
or short to voltage.
2. Injector malfunction.
3. ECM malfunction.
B5 -

6E-138 3.5L ENGINE DRIVEABILITY AND EMISSIONS Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure Parts Related
ECM Pin
No. Related
Multiple
DTC
P0404 B EGR Circuit
Range/Performance (Open
Valve) 1. Engine is stopping.
2. No DTC relating to ECT sensor, CKP sensor
and VSS.
3. Vehicle speed is below 4km/h.
4. Engine coolant temperature is more than
75
C.
5. EGR solenoid valve on-duty ratio is more than
100%.
6. EGR valve output monitoring signal high. EGR valve output monitoring
signal low. 1. EGR solenoid harness short to voltage circuit.
2. EGR valve sticking.
3. ECM malfunction. A5 - P1404 B EGR Circuit
Range/Performance (Closed
Valve) 1. Engine is running.
2. Engine speed is below 4000rpm.
3. No DTC relating to CKP sensor.
4. EGR solenoid valve on-duty ratio is 0%.
5. EGR valve output monitoring signal low. 1. EGR operation is stopped.
2. EGR valve closed position
learning operation is
disabled.
3. EGR position feedback is
disabled.

EGR valve output monitoring
signal high. 1. EGR solenoid harness open circuit or short to
ground circuit.
2. EGR valve sticking.
3. ECM malfunction. A5 - P0405 B EGR Circuit Low
1. No DTC relating to EGR circuit
range/performance.
2. EGR solenoid valve on-duty ratio is more than
40%.
3. EGR position sensor output voltage is below
0.3V. EGR position sensor output
voltage is more than 0.3V. 1. EGR position sensor power supply circuit
open or short to ground circuit.
2. EGR position sensor signal circuit open or
short to ground circuit.
3. Poor connector connection.
4. EGR valve malfunction.
5. ECM malfunction. A9/
A24 - P0406 B EGR Circuit High
1. No DTC relating to EGR circuit
range/performance.
2. EGR solenoid valve on-duty ratio is below
40%.
3. EGR position sensor output voltage is more
than 4.6V. No fail-safe function.

EGR position sensor output
voltage is below 4.6V. 1. EGR position sensor power supply circuit
short to voltage circuit.
2. EGR position sensor signal circuit short to
voltage circuit.
3. EGR position sensor ground circuit open or
short to voltage circuit.
4. Poor connector connection.
5. EGR valve malfunction.
6. ECM malfunction. A9/
A22/
A24 P0118 P0444 A EVAP Purge Solenoid Valve
Circuit Low Voltage 1. No DTC relating to CKP sensor and system
voltage.
2. Engine speed is below 4000rpm.
3. Purge solenoid valve on-duty ratio is below
48%.
4. Purge solenoid valve output monitoring signal
low. Purge solenoid valve output
monitoring signal high. 1. Solenoid harness open circuit or short to
ground.
2. Solenoid malfunction.
3. ECM malfunction. B15 -
32
P0445 A EVAP Purge Solenoid Valve
Circuit High Voltage 1. No DTC relating to CKP sensor and system
voltage.
2. Engine speed is below 4000rpm.
3. Purge solenoid valve on-duty ratio is more
than 50%.
4. Purge solenoid valve output monitoring signal
high. No fail-safe function.

Purge solenoid valve output
monitoring signal low. 1. Solenoid harness short to voltage.
2. Solenoid malfunction.
3. ECM malfunction. B15 -

6E-140 3.5L ENGINE DRIVEABILITY AND EMISSIONS Flash
Code Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up) Recovery Condition Related Failure Parts Related
ECM Pin
No. Related
Multiple
DTC
P1508 B Idle Air Control System
Low/Closed 1. No DTC relating to MAF sensor, IAT sensor,
ECT sensor, TPS, CMP sensor, CKP sensor,
VSS and system voltage.
2. Engine speed is between 675rpm and
6000rpm.
3. Engine coolant temperature is more than
75
C.
4. Intake air temperature is between -10
C and
80
C.
5. Vehicle is stopping.
6. Small amount of intake air through the idle air
control valve. (Idle air control valve is sticking
at close position.) Above conditions are met
for 2 seconds. 1. IAC valve harness open circuit, short to
ground circuit or short to voltage circuit.
2. Poor connector connection.
3. IAC valve malfunction.
4. IAC valve is sticking at close position.
5. ECM malfunction. B13/
B14/
B16/
B17 -
22
P1509 B Idle Air Control System
High/Open 1. No DTC relating to MAF sensor, IAT sensor,
ECT sensor, TPS, CMP sensor, CKP sensor,
VSS and system voltage.
2. Engine speed is between 675rpm and
6000rpm.
3. Engine coolant temperature more than 75
C.
4. Intake air temperature is between -10
C and
80
C.
5. Vehicle is stopping.
6. Large amount of intake air through the idle air
control valve. (Idle air control valve is sticking
at open position.) Above conditions are met
for 2 seconds. Fuel cut is operated at high idle
speed.
Correct amount of air intake
through the idle air control
valve. (Correct movement of
the idle air control valve.)

1. IAC valve harness open circuit, short to
ground circuit or short to voltage circuit.
2. Poor connector connection.
3. IAC valve malfunction.
4. IAC valve is sticking at open position.
5. ECM malfunction. B13/
B14/
B16/
B17 - 65 P1601 D CAN BUS Off CAN BUS off condition is detected consecutively.
CAN BUS on condition is
detected consecutively for 2
seconds. 1. ECM and TCM communication circuit open,
short to ground or short to voltage.
2. Electrical interference.
3. ECM malfunction.
4. TCM malfunction. A10/
A11 - 67 U2104 D CAN BUS Reset Counter
Overrun 1. No DTC CAN BUS Off.
2. CAN valid counter does not change for 2
seconds. Torque reduction control is
disable.
CAN valid counter changes
consecutively for 2 seconds. 1. ECM and TCM communication circuit open,
short to ground or short to voltage.
2. Electrical interference.
3. ECM malfunction.
4. TCM malfunction. A10/
A11 P1767/
U2104 (AT)

6E-142 3.5L ENGINE DRIVEABILITY AND EMISSIONS
MULTIPLE DTC SETS TROUBLESHOOTING AIDS
An open or short to voltage circuit in the sensor ground circuit between the ECM terminal A22 and splice will cause
one or more of following DTCs to be set:





P0406 (Flash Code 32): EGR Circuit High





P0118 (Flash Code 14): Engine Coolant Temperature Sensor High Input

A short to ground circuit in the sensor power supply circuit between the ECM terminal A24 and splice will cause one
or more of following DTCs to be set:





P0122 (Flash Code 21): Throttle Position Sensor Low Input





P0336 (Flash Code 29): Crankshaft Position Sensor Circuit Range/Performance (58X)





P0337 (Flash Code 29): Crankshaft Position Sensor Circuit No Signal (58X)


RTW46EMF000201

6E-168 3.5L ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P0117 (FLASH CODE 14) ENGINE
COOLANT TEMPERATURE (ECT) SENSOR LOW INPUT



RUW46EMF000201

Condition For Setting The DTC and Action Taken When The DTC Sets
Flash
Code
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
14 P0117 A Engine Coolant
Temperature Sensor
Low Input
ECT sensor output voltage is below 0.08V. The ECM uses default engine
coolant temperature value based on
start-up ECT and time from start.

Circuit Description
The engine coolant temperature (ECT) sensor is a
thermistor mounted on a coolant crossover pipe at the
rear of the engine. The Engine Control Module (ECM)
applies a voltage (about 5 volts) through a pull-up
resistor to the ECT signal circuit. When the engine
coolant is cold, the sensor (thermistor) resistance is
high, therefore the ECM will measure a high signal
voltage. As the engine coolant warms, the senso
r
resistance becomes lower, and the ECT signal voltage
measured at the ECM drops.

DIAGNOSTIC AIDS
Check for the following conditions:
 Poor connection at ECM – Inspect harness
connectors for backed-out terminals, imprope
r
mating, broken locks, improperly formed or damaged
terminals, and poor terminal-to-wire connection.
 Damaged harness –Inspect the wiring harness fo
r
damage. If the harness appears to be OK, observe
the ECT display on the Tech 2 while moving
connectors and wiring harnesses related to the ECT
sensor. A change in the ECT display will indicate the
location of the fault.
If DTC P0117 cannot be duplicated, the information
included in the Failure Records data can be useful in
determining vehicle mileage since the DTC was last set.
If it is determined that the DTC occurs intermittently.

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-169
Diagnostic Trouble Code (DTC) P0117 (Flash Code 14) Engine Coolant
Temperature (ECT) Sensor Low Input
Step Action Value (s) Yes No
1 Was the "On-Board Diagnostic (OBD) System Check"
performed?
- Go to Step 2 Go to On Board
Diagnostic (OBD)
System Check
2
1. Connect the Tech 2.
2. Review and record the failure information.
3. Select "F0: Read DTC Infor By Priority" in "F0:
Diagnostic Trouble Code".
Is the DTC P0117 stored as "Present Failure"?
- Go to Step 3 Refer to
Diagnostic Aids
and Go to Step 3
3
1. Using the Tech2, ignition "On" and engine "Off".
2. Select "Clear DTC Information" with the Tech2 and
clear the DTC information.
3. Operate the vehicle and monitor the "F5: Failed
This Ignition" in "F2: DTC Information"
Was the DTC P0117 stored in this ignition cycle?
-
Go to Step 4 Refer to
Diagnostic Aids
and Go to Step 4
4
Check for poor/faulty connection at the ECT sensor or
ECM connector. If a poor/faulty connection is found,
repair as necessary.
Was the problem found?
E-69
E-60(A)







- Verify repair Go to Step 5
5
Visually check the ECT sensor.
Was the problem found?
- Go to Step 8 Go to Step 6