2004 ISUZU TF SERIES brake sensor

6E–274 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The ECM monitors the brake switch signal on the feed
terminal to the ECM. If brake switch 1 or 2 circuit with
malfunction, DTC P0703 (Symptom Code A) or P0703
(Symptom Code B) will be stored.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.Rubbed through wire insulation.
Broken wire inside the insulation.
Check for the following conditions:
Poor connection at ECM-Inspect harness connectors
for backed out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal to wire connection.
Damaged harness-Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the “Brake Switch 1” and “Brake Switch 2” display on
the Tech2 while moving connectors and wiring
harness related to the sensor.
Diagnostic Trouble Code (DTC) P0703 (Symptom Code A) (Flash Code 25)
Brake Switch Circuit Malfunction
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
25 P0703 A ON Bra ke Switch Circuit
Malfunctio n1. Thro ttle po sitio n is more
tha n 0%.
2. Engine speed is more than
693rpm (4JA1-TC) or
665rpm (4JH1-TC).
3. Vehicle speed is more than
0km/h.
4. Brake switch 1 signal and
brake switch 2 signal are
differently inputted to the
ECM since the ignition
sw it ch w a s tur ne d o n.No fa il-sa fe fun ctio n.
B ON Bra ke Switch Circuit
Malfunctio n1. Thro ttle po sitio n is more
tha n 0%.
2. Engine speed is more than
693rpm (4JA1-TC) or 665
rpm (4JH1-TC).
3. Vehicle speed is more than
0km/h.
4. Brake switch 1 signal and
brake switch 2 signal are
differently inputted to the
ECM.
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go 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 As Stored By ECU” in
“F0: Diagnostic Trouble Codes”.
Is the DTC P0703 (Symptom Code A) stored as
“Present Failure”?—Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–287
DIAGNOSTIC TROUBLE CODE (DTC) P1120 (SYMPTOM CODE 1)
(FLASH CODE 21) PEDAL/THROTTLE POSITION SENSOR CIRCUIT HIGH
INPUT
DIAGNOSTIC TROUBLE CODE (DTC) P1120 (SYMPTOM CODE 7)
(FLASH CODE 21) PEDAL/THROTTLE POSITION SENSOR VOLTAGE SUPPLY
CIRCUIT HIGH INPUT
DIAGNOSTIC TROUBLE CODE (DTC) P1120 (SYMPTOM CODE 9)
(FLASH CODE 21) PEDAL/THROTTLE POSITION SENSOR VOLTAGE SUPPLY
CIRCUIT LOW INPUT
DIAGNOSTIC TROUBLE CODE (DTC) P1120 (SYMPTOM CODE D)
(FLASH CODE 21) PEDAL/THROTTLE POSITION SENSOR BRAKE SWITCH
ERROR
DIAGNOSTIC TROUBLE CODE (DTC) P1120 (SYMPTOM CODE E)
(FLASH CODE 21) PEDAL/THROTTLE POSITION SENSOR IDLE POSITION
SWITCH ERROR

6E–288 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The TPS is a potentiometer connected to throttle shaft
on the throttle body. It is installed to the main TPS and
idle switch.
The engine control module (ECM) monitors the voltage
on the signal line and calculates throttle position. As the
throttle valve angle is changed when accelerator pedal
moved. The TPS signal also changed at a moved
throttle valve. As the throttle valve opens, the output
increases so that the output voltage should be high.
The ECM monitors the TPS supply voltage and TPS
output voltage. The supply voltage is out of range, DTC
P1120 (Symptom Code 7) or P1120 (Symptom Code 9)
will be stored. The output voltage excessively high, DTC
P1120 (Symptom Code 1) will be stored.
If the brake pedal is depressed during accelerator pedal
is depressing, DTC P1120 (Symptom Code D) will be
stored.
If the relation of idle switch and TPS position are
incorrect, DTC P1120 (Symptom Code E) will be stored.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.
Rubbed through wire insulation.
Broken wire inside the insulation.
Check for the following conditions:
Poor connection at ECM-Inspect harness connectors
for backed out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal to wire connection.
Damaged harness-Inspect the wiring harness for
damage. If the harness appears to be OK, observe
the “Throttle Position”, “Idle Switch”, “Brake Switch 1”
and “Brake Switch 2” display on the Tech2 while
moving connectors and wiring harness related to the
sensor.
Diagnostic Trouble Code (DTC) P1120 (Sy mptom Code 1) (Flash Code 21)
Pedal/Throttle Position Sensor Circuit High Input
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
21 P1120 1 ON Pedal/Throttle Position Sen-
sor Circuit High InputThrottle position sensor out-
put voltage is more than 4.5V.ECM increa ses idle spe ed up
to 1400rpm.
7 ON Pedal/Throttle Position Sen-
sor Voltage Supply Circuit
High InputThrottle position sensor
power supply voltage is more
than 5.2V.
9 ON Pedal/Throttle Position Sen-
sor Voltage Supply Circuit
Lo w InputThrottle position sensor
power supply voltage is below
4.6V.
D ON Pedal/Throttle Position Sen-
sor Brake Switch Error1. Engine speed is more than
1700rpm.
2. Vehicle speed is more than
1.5km/h.
3. When brake pedal is
depressed during accelera-
tor pe da l is de pre ssing.
E ON Pedal/Throttle Position Sen-
sor Idle Position Switch Error1. Whe n idle switch is turne d
o ff, thro ttle positio n se nsor
wa s be lo w 0.35%.
or
2. Whe n idle switch is tune d
on, throttle position sensor
was more than 7.8%.
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go to On Board
Diagnostic
(OBD) System
Check

6E–298 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
Diagnostic Trouble Code (DTC) P1120 (Sy mptom Code D) (Flash Code 21)
Pedal/Throttle Position Sensor Brake Switch Error
Step Action Value(s) Yes No
1Was the “On-Board Diagnostic (OBD) System Check”
performed?
—Go to Step 2Go 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 As Stored By ECU” in
“F0: Diagnostic Trouble Codes”.
Is the DTC P1120 (Symptom Code D) stored as
“Present Failure”?—Go to Step 3Refer to
Diagnostic Aids
and Go to Step
3
3 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Select “F1: Clear DTC Information” in “F0:
Diagnostic Trouble Codes” with the Tech 2 and
clear the DTC information.
3. Operate the vehicle and monitor the “F0: Read
DTC Infor As Stored By ECU” in the “F0:
Diagnostic Trouble Codes”.
Was the DTC P1120 (Symptom Code D) stored in this
ignition cycle?—Go to Step 4Refer to
Diagnostic Aids
and Go to Step
4
4 Visually check the TPS.
Check for the following conditions.
Accelerator pedal sticking.
If a problem is found, repair as necessary.
Was the problem found? —Verify repair Go to Step 5
5 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Throttle Position” in the data display.
Does the Tech 2 indicate correct “Throttle Position”
from 0% to 100% depending on accelerator pedal
operation?—Go to Step 7Go to Step 6
6 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Throttle Position” in the data display.
3. Adjust the TPS within 0% to 100%.
Was the problem solved?—Verify repair Go to Step 11
7 1. Using the Tech 2, ignition “On” and engine “Off”.
2. Monitor the “Brake Switch 1” and “Brake Switch 2”
in the data display.
Does the Tech 2 indicate “Inactive” when the brake
pedal was not stepped on?—Go to Step 13Go to Step 8
8 Adjust the brake switch.
Was the problem solved?—Verify repair Go to Step 9
9 Substitute a known good brake switch and recheck.
Was the problem solved?—Go to Step 10Go to Step 13
10 Replace the brake switch.
Is the action complete?—Verify repair—
11 Substitute a known good TPS and recheck.
Was the problem solved?—Go to Step 12Go to Step 13
12 Replace the TPS.
Is the action complete?—Verify repair—

ENGINE MECHANICAL (6VE1 3.5L) 6A-11
Symptom Possible Cause Action
Engine overheating Level of Engine Coolant too low Replenish
Fan clutch defective Replace
Thermostat defective Replace
Engine Coolant pump defective Correct or replace
Radiator clogged Clean or replace
Radiator filler cap defective Replace
Level of oil in engine crankcase too
low or wrong engine oil Change or replenish
Resistance in exhaust system
increased Clean exhaust system or replace
defective parts
Throttle Position Sensor adjustment
incorrect Replace with Throttle Valve ASM
Throttle Position Sensor circuit open
or shorted Correct or replace
Cylinder head gasket damaged Replace
Engine overcooling Thermostat defective Replace (Use a thermostat set to
open at 82
C (180
F))
Engine lacks compression ———— Refer to Hard Start
Others Tire inflation pressure abnormal Adjust to recommended pressures
Brake drag Adjust
Clutch slipping Adjust or replace
Level of oil in engine crankcase too
high Correct level of engine oil
EGR valve defective Replace

6E-334 3.5L ENGINE DRIVEABILITY AND EMISSIONS
HARD START SYMPTOM
DEFINITIONS: Engine cranks, but does not start for a
long time. Does eventually start, or may start and then
immediately stall.



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. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
- Verify repair Go to Step 3
3
Was a visually/physical check performed?
- Go to Step 4 Go to Visual /
physical Check
4
1. Using a Tech 2, display the ECT sensor and IAT
sensor value.
2. Check the specified value or wire.
Was the problem found?
- Verify repair Go to Step 5
5
Check the ECM grounds to verify that they are clean
and tight. Refer to the ECM wiring diagrams.
Was a problem found?
- Verify repair Go to Step 6
6
Visually/physically inspect for the following conditions:

Restrict air intake system. Check for a restricted air
filter element, or foreign objects blocking the air
intake system.

Check for objects blocking the IAC passage or
throttle bore, excessive deposits in the throttle bore
and on the throttle plate.

Check for a condition that causes a large vacuum
leak, such as an incorrectly installed or faulty
crankcase ventilation hose/brake booster hose.
Was a problem found?
- Verify repair Go to Step 7
7
1. Using a Tech 2, display the IAC value.
2. Check for a faulty, plugged, or sticking IAC
operation.
Was the problem found?
- Verify repair Go to Step 8
8
Check the CKP sensor signal or installation condition.
Refer to DTC P0336 "Crankshaft Position Sensor
Circuit Range/Performance" and DTC P0337
"Crankshaft Position Sensor Circuit No Signal".
Was a problem found?
- Verify repair Go to Step 9
9
Check for proper ignition voltage output with a spark
tester.
Was the problem found?
- Verify repair Go to Step 10

3.5L ENGINE DRIVEABILITY AND EMISSIONS 6E-337
ROUGH, UNSTABLE, OR INCORRECT IDLE, STALLING SYMPTOM
DEFINITIONS: Engine runs unevenly at idle. If severe,
the engine or vehicle may shake. Engine idle speed
may vary in RPM. Either condition may be severe
enough to stall the engine.





X

time rpm
Rough Idle
Stall



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. Perform a bulletin search.
2. If a bulletin that addresses the symptom is found,
correct the condition as instructed in the bulletin.
Was a bulletin found that addresses the symptom?
- Verify repair Go to Step 3
3
Was a visually/physical check performed?
- Go to Step 4 Go to Visual /
physical Check
4
1. Check for incorrect idle speed. Ensure that the
following conditions are present.

Engine fully warm.

Accessories are OFF. 2. Using a Tech 2, monitor
IAC position.
Is the IAC position within the specified values?
10 - 20 StepsGo to Step 6 Go to Step 5
5
Visually/physically inspect for the following conditions:

Restrict air intake system. Check for a restricted air
filter element, or foreign objects blocking the air
intake system.

Check for objects blocking the IAC passage or
throttle bore, excessive deposits in the throttle bore
and on the throttle plate.

Check for a condition that causes a large vacuum
leak, such as an incorrectly installed or faulty
crankcase ventilation hose/brake booster hose.
Was a problem found?
- Verify repair Go to Step 6
6
1. Using a Tech 2, display the ECT sensor and IAT
sensor value.
2. Check the specified value or wire.
Was the problem found?
- Verify repair Go to Step 7

6-8 ENGINE DIAGNOSIS (C24SE)
Condition Possible cause Correction
Engine overheating Level of Engine Coolant too low Replenish
Thermo switch or fan motor
defective Replace
Thermostat defective Replace
Engine Coolant pump defective Correct or replace
Radiator clogged Clean or replace
Radiator filter cap defective Replace
Level of oil in engine crankcase
too low or wrong oil in engine Change or replenish
Resistance in exhaust system
increased Clean exhaust system or replace
defective parts
Throttle Position Sensor
adjustment incorrect Adjust Wide Open Throttle switch
setting
Throttle Position Sensor circuit
open or shorted Correct or replace
Cylinder head gasket damaged Replace
Cooling Fan clutch defective Replace
Fan belt slipping Adjust tension of V-belt or replace
V-belt
Engine overcooling Thermostat defective Replace (Use a thermostat set to
open at 92
C (197.6
F))
Engine lacks compression - Refer to Hard Start
Others Tire inflation pressure abnormal Adjust to recommend pressures
Brake drag Adjust
Clutch slipping Adjust or replace
Level of oil in engine crankcase
too high Correct level of engine oil

Engine Noisy
Abnormal engine noise often consists of various
noises originating in rotating parts, sliding parts and
other moving parts of the engine. It is, therefore,
advisable to locate the source of noise systematically.

Condition Possible cause Correction
Noise from crank journals or from
crank bearings
(Faulty crank journals and crank
bearings usually make dull noise
that becomes more evident when
accelerating) Oil clearance increased due to
worn crank journals or crank
bearings Replace crank bearings and
crankshaft or regrind crankshaft
and install the over size bearing
Crankshaft out of round Replace crank bearings and
crankshaft or regrind crankshaft
and install the over size bearing
Crank bearing seized Replace crank bearings and
crankshaft or regrind crankshaft
and install the over size bearing