Glow plugs ISUZU TF SERIES 2004 Workshop Manual

ENGINE ELECTRICAL 6D – 33
PRE-HEATING SYSTEM
INSPECTION AND REPAIR
Make the necessary adjustments, repairs, and part replacement if excessive wear of damage is discovered during
inspection.

VISUAL CHECK
Check the main fuses and glow indicator for damage.
Replace the part(s) if required.
GLOW RELAY
The glow relay is located in the relay box the engine
compartment.



825R300046




Use an ohmmeter to measure the resistance between
terminals No.2 and No.3.
If the measured value is outside the specified range, the
glow relay must be replaced.
Glow Relay Resistance Ohms
94  114

GLOW PLUG


LNW21KSH001401
Use a circuit tester to test the glow plugs for continuity.
Glow Plug Resistance (Reference) Ohms
Approximately 0.9

EGR SYSTEM 4JA1T (L)
Refer to 6F-9. (EGR system diagram)

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–217
DIAGNOSTIC TROUBLE CODE (DTC) P0380 (SYMPTOM CODE 4)
(FLASH CODE 66) GLOW RELAY CIRCUIT VOLTAGE LOW
DIAGNOSTIC TROUBLE CODE (DTC) P0380 (SYMPTOM CODE 8)
(FLASH CODE 66) GLOW RELAY CIRCUIT VOLTAGE HIGH
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The voltage on the coil of the relay glow plug is supplied
by the relay engine control module (ECM) main. The
ECM switches glow relay to operate glow plug depends
on the coolant temperature.
In the after glow phase the lamp is not illuminated but
the glow plugs remain active for a certain period
depending on engine coolant temperature.
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:
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
66 P0380 4 ON Glo w Re la y Circuit Volta ge
Lo wGlow relay circuit open or
sho rt to ground circuit.No fa il-sa fe fun ctio n.
8 ON Glo w Re la y Circuit Volta ge
HighGlo w re la y circuit short to vo lt-
age circuit.

6E–222 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P0381 (SUB CODE 4) (FLASH CODE 67)
GLOW PLUG INDICATOR CIRCUIT VOLTAGE LOW
DIAGNOSTIC TROUBLE CODE (DTC) P0381 (SUB CODE 8) (FLASH CODE 67)
GLOW PLUG INDICATOR CIRCUIT VOLTAGE HIGH
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The function of the glow time indicator lamp is to inform
the driver whether the glow system is activated.
When the lamp turned off, the engine can be started.
This does not imply that the glow plugs are no longer
activated.
In the after glow phase the lamp is not illuminated butthe glow plugs remain active for a certain period
depending on engine coolant temperature.
Diagnostic Aids
An intermittent may be caused by the following:
Poor connections.
Misrouted harness.
Flash
CodeCode Symptom
CodeMIL DTC Name DTC Setting Condition Fail-Safe (Back Up)
67 P0381 4 ON Glo w Plug Indica to r Circuit
Voltage LowGlo w plug indicator circuit
open or short to ground cir-
cuit.No fa il-sa fe fun ctio n.
8 ON Glo w Plug Indica to r Circuit
Vo lta ge HighGlo w plug indicator circuit
short to voltage circuit.

4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS 6E–367
10 1. Using the Tech 2, ignition “On”.
2. Monitor the “Glow Time Relay” in the data display
and then, does the supply voltage correctly supply
to the glow plug?
—Go to Step 11Repair voltage
supply circuit
and verify repair
11 Check the glow plugs for continuity.
If a problem is found, repair as necessary.
Was a problem found?
—Verify repair Go to Step 12
12 Check the ex haust system for a possible restriction.
Damaged or collapsed pipes or catalytic converter.
Internal muffler failure.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 13
13 Visually/physically inspect for the following conditions.
Restrict fuel supply system. Check for a pinched
fuel hose/pipe.
Check for a condition that causes fuel wax ing or
icing, such as the customer is using an incorrect
fuel type in winter season or water mix ed with the
fuel.
If a problem is found, repair as necessary.
Was a problem found?—Verify repair Go to Step 14
14 Replace the fuel filter.
Was the problem solved?—Verify repair Go to Step 15 Step Action Value(s) Yes No

6E–408 4JA1/4JH1 ENGINE DRIVEABILITY AND EMISSIONS
12 Substitute a known good MAF & IAT sensor assembly
and recheck.
Was the problem solved?—Go to Step 13Go to Step 30
13 Replace the MAF & IAT sensor assembly.
Is the action complete?—Veri fy repai r—
14 1. Using the Tech 2, ignition “On” and engine “Run”.
2. Monitor the “Glow Time Relay” in the data display.
Does the Tech 2 indicate correct “Glow Time Relay”
status depending on the time from engine “Run”?
If a problem is found, repair as necessary.
Was the problem found?—Go to Step 30Go to Step 15
15 1. Using the Tech 2, ignition “On” and engine “Run”.
2. Monitor the “Glow Time Relay” in the data display
and then, does the supply voltage correctly supply
to the glow plug?
—Go to Step 16Repair voltage
supply circuit
and verify repair
16 Check the glow plugs for continuity.
If a problem is found, repair as necessary.
Was a problem found?
—Verify repair Go to Step 17
17 Remove the CKP sensor from the flywheel housing
and check for the following conditions.
Objects sticking the CKP sensor.
Objects sticking the CKP sensor pulser.
If a problem is found, repair as necessary.
Was the problem found? —Verify repair Go to Step 18
18 Check the CKP sensor harness for the following
conditions.
Check for poor connector connection.
Check for misrouted harness.
Check for any accessory parts which may cause
electric interference.
If a problem is found, repair as necessary.
Was a problem found? —Verify repair Go to Step 19 Step Action Value(s) Yes No