2007 ISUZU KB P190 Engine wiring

6E–218 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P1626 IMMOBILIZER NO SIGNAL
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The ECM decides whether that is an abnomality in the
immobilizer control system. DTC P1626 is recorded by
the ECM when no response from immobiliser.
Diagnostic Aids
Check for the following conditions:
• Poor connection at ECM and Immobilizer-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, disconnect
the ECM and Immobilizer, turn the ignition “ON” and
observe a voltmeter connected to the suspect driver
circuit at the ECM and Immobilizer harnass connector
while moving connectors and wiring harnesses
relates to the MIL. A change in voltage will indicate
the location of the fault.
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P1626 - Immobilizer No Signal No response from immobilizer control unit. 1. Engine does not start.
2. Check engine lamp flash.

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ISUZU KB P190 2007

6E–222 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P1631 IMMOBILIZER WRONG SIGNAL
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The ECM decides whether that is an abnomality in the
immobilizer control system. DTC P1631 is recorded by
the ECM when received response was not correct.
Diagnostic Aids
Check for the following conditions:
• Poor connection at ECM and Immobilizer-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, disconnect
the ECM and Immobilizer, turn the ignition “ON” and
observe a voltmeter connected to the suspect driver
circuit at the ECM and Immobilizer harnass connector
while moving connectors and wiring harnesses
relates to the MIL. A change in voltage will indicate
the location of the fault.
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P1631 - Immobilizer Wrong Signal Received response is not correct.1. Engine does not start.
2. Check engine lamp flash.

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ISUZU KB P190 2007

6E–224 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P1648 WRONG SECURITY CODE ENTERED
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The ECM decides whether that is an abnomality in the
immobilizer control system. DTC P1648 is recorded by
the ECM when received incorrect security code.
Diagnostic Aids
Check for the following conditions:
• Poor connection at ECM and Immobilizer-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, disconnect
the ECM and Immobilizer, turn the ignition “ON” and
observe a voltmeter connected to the suspect driver
circuit at the ECM and Immobilizer harnass connector
while moving connectors and wiring harnesses
relates to the MIL. A change in voltage will indicate
the location of the fault.
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P1648 - Wrong Security Code Entered Received incorrect security code. 1. Engine does not start.
2. Check engine lamp flash.

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ISUZU KB P190 2007

6E–226 ENGINE DRIVEABILITY AND EMISSIONS
DIAGNOSTIC TROUBLE CODE (DTC) P1649
IMMOBILIZER FUNCTION NOT PROGRAMMED
Condition for setting the DTC and action taken when the DTC sets
Circuit Description
The ECM decides whether that is an abnomality in the
immobilizer control system. DTC P1649 is recorded by
the ECM when security code & secret key not
programmed.
Diagnostic Aids
Check for the following conditions:
• Poor connection at ECM and Immobilizer-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, disconnect
the ECM and Immobilizer, turn the ignition “ON” and
observe a voltmeter connected to the suspect driver
circuit at the ECM and Immobilizer harnass connector
while moving connectors and wiring harnesses
relates to the MIL. A change in voltage will indicate
the location of the fault.
Code Type DTC Name DTC Setting Condition Fail-Safe (Back Up)
P1649 - Immobilizer Function Not Programmed Immobilizer function is not programmed in the ECM.1. Engine does not start.
2. Check engine lamp flash.

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ISUZU KB P190 2007

6E–232 ENGINE DRIVEABILITY AND EMISSIONS
SYMPTOM DIAGNOSIS
PRELIMINARY CHECKS
Before using this section, perform the “On-Board
Diagnostic (OBD) System Check” and verify all of the
following items:
• The engine control module (ECM) and malfunction indicator lamp (MIL = Check Engine Lamp) are
operating correctly.
• There are no Diagnostic Trouble Code(s) stored.
• Tech 2 data is within normal operating range. Refer to Typical Scan Data Values.
• Verify the customer complaint and locate the correct symptom in the table of contents. Perform the
procedure included in the symptom chart.
VISUAL/PHYSICAL CHECK
Several of the symptom procedures call for a careful
visual/physical check. This can lead to correcting a
problem without further checks and can save valuable
time. This check should include the following items:
• ECM grounds for cleanliness, tightness and proper location.
• Vacuum hoses for splits, kinks, and proper connection, shown on the “Emission Control System
Schematics”. Check thoroughly for any type of leak or
restriction.
• Air intake ducts for collapsed or damaged areas.
• Air leaks at throttle body mounting area, manifold absolute pressure (MAP) sensor and intake manifold
sealing surfaces.
• Ignition wires for cracking, harness, and carbon tracking.
• Wiring for proper connections, pinches and cuts.
INTERMITTENT
Important: An intermittent problem may or may not turn
on the malfunction indicator lamp (MIL) or store a
Diagnostic Trouble Code. Do NOT use the Diagnostic
Trouble Code (DTC) charts for intermittent problems.
The fault must be present to locate the problem.
Most intermittent problems are cased by faulty electrical
connections or wiring. Perform a careful visual/physical
check for the following conditions.
• Poor mating of the connector halves or a terminal not fully seated in the connector (backed out).
• Improperly formed or damaged terminal.
• All connector terminals in the problem circuit should be carefully checked for proper contact tension.
• Poor terminal-to-wire connection. This requires removing the terminal form the connector body to
check.
• Ignition coils shorted to ground and arcing at ignition wires or plugs. • MIL (Check Engine Lamp) wire to ECM shorted to
ground.
• Poor ECM grounds. Refer to the ECM wiring diagrams.
Road test the vehicle with a Digital Multimeter
connected to a suspected circuit. An abnormal voltage
when the malfunction occurs is a good indication that
there is a fault in the circuit being monitored.
Using Tech 2 to help detect intermittent conditions. The
Tech 2 has several features that can be used to located
an intermittent condition.
An intermittent MIL (Check Engine Lamp) with no stored
Diagnostic Trouble Code may be caused by the
following:
• Ignition coil shorted to ground and arcing at ignition wires or plugs.
• MIL (Check Engine Lamp) wire to ECM short to ground.
• Poor ECM grounds. Refer to the ECM wiring diagrams.
Check for improper installation of electrical options such
as light, cellular phones, etc. Check all wires from ECM
to the ignition control module for poor connections.
Check for an open diode across the A/C compressor
clutch and check for other open diodes (refer to wiring
diagrams in Electrical Diagnosis).
If problem has not been found, refer to ECM connector
symptom tables.
• Check the “Broadcast Code” of the ECM, and compare it with the latest Isuzu service bulletins and/
or Isuzu EEPROM reprogramming equipment to
determine if an update to the ECM’s reprogrammable
memory has been released.
To check the “Broadcast Code”, connect the Tech 2,
then look for “ID info.” then select “Broadcast Code”.
This should display a 4 character code, such as “XBYA”
(example only).
This identifies the contents of the reprogrammable
software and calibration contained in the ECM.
If the “Broadcast Code” is not the most current
available, it is advisable to reprogram the ECM’s
EEPROM memory, which may either help identify a
hard-to find problem or may fix the problem.
The Service Programming System (SPS) will not allow
incorrect software programming or incorrect calibration
changes.

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ISUZU KB P190 2007

ENGINE DRIVEABILITY AND EMISSIONS 6E–243
9 Check the fuel pressure. Refer to 6E-108 page“Fuel
System Diagnosis
”.
Was a problem found? — Verify repair Go to Step 10
10 Monitor “ B1S1 (Bank 1 Sensor 1) Status ” on the Tech
2.
Is the “ B1S1 (Bank 1 Sensor 1) Status ” in the rich
condition? — Verify repair Go to Step 11
11 Check items that can cause the engine to run rich. Refer to DTC P1167 “Fuel Supply System Rich During
Deceleration Fuel Cut Off”.
Was a problem found? — Verify repair Go to Step 12
12 Check items that can cause the engine to run lean. Refer to DTC P1171 “Fuel Supply System Lean
During Power Enrichment”.
Was a problem found? — Verify repair Go to Step 13
13 Check for proper ignition voltage output with the spark tester.
Was a problem found? — Verify repair Go to Step 14
14 Check for a loose ignition control module ground. Was a problem found? — Verify repair Go to Step 15
15 Visually/physically inspect all spark plug high-tension cables. Check for the following conditions:
• Verify that the resistance of all spark plug high- tension cables are less than the specified value.
• Verify that the all spark plug high-tension cables are correctly fitted to eliminate cross-fitting.
• Verify that the all spark plug high-tension cables are not arcing to ground.
Spraying the spark plug high-tension cables with a
light mist of water may help locate an intermittent
problem.
Was a problem found? #1 cyl. 4.4k
Ω
#2 cyl. 3.6k Ω
#3 cyl. 3.1k Ω
#4 cyl. 2.8k ΩVerify repair Go to Step 16
16 1. Check the ignition coil secondary resistance. 2. Replace the coil if it is greater than the specifiedresistance.
Did the coil require replacement? 2.5kΩ Verify repair Go to Step 17
17 1. Remove the spark plugs and check for gas or oil fouling cracks, wear, improper gap, burned
electrodes, heavy deposits, or improper heat
range.
2. If spark plugs are fouled, the cause of fouling must be determined before replacing the spark plugs.
Was a problem found? — Verify repair Go to Step 18
18 1. Check the injector connectors. 2. If any of the connectors are connected at animproper cylinder, connect as necessary.
Was a problem found? — Verify repair Go to Step 19
19 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 20
20 Visually/physically check the vacuum hose for splits, kinks and proper connections and routing.
Was a problem found? — Verify repair Go to Step 21
Step
Action Value(s) Yes No

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ISUZU KB P190 2007

6E–246 ENGINE DRIVEABILITY AND EMISSIONS
10 Monitor “B1S1 (Bank 1 Sensor 1) Status ” on the Tech
2.
Is the “ B1S1 (Bank 1 Sensor 1) Status ” in the rich
condition? — Go to Step 11Go to Step 12
11 Check items that can cause the engine to run rich. Refer to DTC P1167 “Fuel Supply System Rich During
Deceleration Fuel Cut Off”.
Was a problem found? — Verify repair Go to Step 12
12 Check items that can cause the engine to run lean. Refer to DTC P1171 “Fuel Supply System Lean
During Power Enrichment”.
Was a problem found? — Verify repair Go to Step 13
13 Check for proper ignition voltage output with the spark tester.
Was a problem found? — Verify repair Go to Step 14
14 Check for a loose ignition control module ground. Was a problem found? — Verify repair Go to Step 15
15 Visually/physically inspect all spark plug high-tension cables. Check for the following conditions:
• Verify that the resistance of all spark plug high- tension cables are less than the specified value.
• Verify that the all spark plug high-tension cables are correctly fitted to eliminate cross-fitting.
• Verify that the all spark plug high-tension cables are not arcing to ground.
Spraying the spark plug high-tension cables with a
light mist of water may help locate an intermittent
problem.
Was a problem found? #1 cyl. 4.4k
Ω
#2 cyl. 3.6k Ω
#3 cyl. 3.1k Ω
#4 cyl. 2.8k ΩVerify repair Go to Step 16
16 1. Check the ignition coil secondary resistance. 2. Replace the coil if it is greater than the specifiedresistance.
Did the coil require replacement? 2.5kΩ Verify repair Go to Step 17
17 1. Remove the spark plugs and check for gas or oil fouling cracks, wear, improper gap, burned
electrodes, heavy deposits, or improper heat
range.
2. If spark plugs are fouled, the cause of fouling must be determined before replacing the spark plugs.
Was a problem found? — Verify repair Go to Step 18
18 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 19
19 Visually/physically check the vacuum hose for splits, kinks and proper connections and routing.
Was a problem found? — Verify repair Go to Step 20
Step
Action Value(s) Yes No

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ISUZU KB P190 2007

6E–248 ENGINE DRIVEABILITY AND EMISSIONS
CUTS OUT, MISSES SYMPTOM
DEFINITIONS: Steady pulsation or jerking that follows
engine speed; usually more pronounced as engine load
increases.
Step Action Value(s) Yes No
1 Was the “ On-Board Diagnostic (OBD) System Check ”
performed? — Go to Step 2Go to
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 visual/physical check performed? —Go to Step 4Go to
Visual /
physical Check .
4 Check the ECM grounds to verify that they are clean and tight. Refer to the ECM wiring diagrams in
Electrical Diagnosis .
Was a problem found? — Verify repair Go to Step 5
5 Check for a loose or short circuit of ignition coil module voltage feed.
Was a problem found? — Verify repair Go to Step 6
6 Check for a loose or short circuit of ignition coil module ground.
Was a problem found? — Verify repair Go to Step 7
7 Visually/physically inspect all spark plug high-tension cables. Check for the following conditions:
• Verify that the resistance of all spark plug high- tension cables are less than the specified value.
• Verify that the all spark plug high-tension cables are correctly fitted to eliminate cross-fitting.
• Verify that the all spark plug high-tension cables are not arcing to ground.
Spraying the spark plug high-tension cables with a
light mist of water may help locate an intermittent
problem.
Was a problem found? #1 cyl. 4.4k
Ω
#2 cyl. 3.6k Ω
#3 cyl. 3.1k Ω
#4 cyl. 2.8k ΩVerify repair Go to Step 7
8 Check the CKP sensor wire, shield wire, or installation condition.
Was a problem found? — Verify repair Go to Step 9
9 Monitor “ B1S1 (Bank 1 Sensor 1) Status ” on the Tech
2.
Is the “ B1S1 (Bank 1 Sensor 1) Status ” in the rich
condition? — Go to Step 10Go to Step 11

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ISUZU KB P190 2007