Isuzu KB P190. Service manual — part 849

Engine Management – V6 – Diagnostics

Page 6C1-2–118

Step Action

Yes

No

10 Replace the ECM. Refer to 6C1-3 Engine Management – V6 –

Service Operations.

Was the repair completed?

Go to Step 11

—

11 1

Using Tech 2, clear the DTCs.

2

Switch off the ignition for 30 seconds.

3

Start the engine.

4

Operate the vehicle within the conditions for running the DTC.

Does any of the CMP Sensor Circuit DTCs fail this ignition cycle?

Go to Step 2

Go to Step 12

12 Using Tech 2, select the DTC display function.

Does Tech 2 display any DTCs?

Go to the

appropriate DTC

Table in this Section

System OK

When all diagnosis and repairs are completed, check the system for correct operation.

7.22 DTC P0351, P0352, P0353, P0354, P0355,

P0356, P2300, P2301, P2303, P2304,
P2306, P2307, P2309, P2310, P2312,
P2313, P2315 or P2316

DTC Descriptors

This diagnostic procedure supports the following DTCs:

•

DTC P0351 – Ignition Coil Cylinder 1 Circuit Malfunction

•

DTC P0352 – Ignition Coil Cylinder 2 Circuit Malfunction

•

DTC P0353 – Ignition Coil Cylinder 3 Circuit Malfunction

•

DTC P0354 – Ignition Coil Cylinder 4 Circuit Malfunction

•

DTC P0355 – Ignition Coil Cylinder 5 Circuit Malfunction

•

DTC P0356 – Ignition Coil Cylinder 6 Circuit Malfunction

•

DTC P2300 – Ignition Coil Cylinder 1 Circuit Low Voltage

•

DTC P2301 – Ignition Coil Cylinder 1 Circuit High Voltage

•

DTC P2303 – Ignition Coil Cylinder 2 Circuit Low Voltage

•

DTC P2304 – Ignition Coil Cylinder 2 Circuit High Voltage

•

DTC P2306 – Ignition Coil Cylinder 3 Circuit Low Voltage

•

DTC P2307 – Ignition Coil Cylinder 3 Circuit High Voltage

•

DTC P2309 – Ignition Coil Cylinder 4 Circuit Low Voltage

•

DTC P2310 – Ignition Coil Cylinder 4 Circuit High Voltage

•

DTC P2312 – Ignition Coil Cylinder 5 Circuit Low Voltage

•

DTC P2313 – Ignition Coil Cylinder 5 Circuit High Voltage

•

DTC P2315 – Ignition Coil Cylinder 6 Circuit Low Voltage

•

DTC P2316 – Ignition Coil Cylinder 6 Circuit High Voltage

Circuit Description

The engine control relay applies positive voltage to the ignition voltage circuit of the ignition coil and the ignition coil dual
line ground circuits are directly connected to ground.

Engine Management – V6 – Diagnostics

Page 6C1-2–119

The ECM applies control voltage to the control circuit of the ignition coil during the calculated dwell period that allows
current flow to the ignition coil primary winding to generate a magnetic flux field. At the appropriate firing point, the ECM
interrupts the control voltage applied to the ignition coil.

Interruption of voltage applied to the control circuit of the ignition coil primary winding induces the transfer of electrical
energy from the ignition coil primary winding to the ignition coil secondary winding, which triggers the ignition coil to
produce a spark at the spark plug.

An ignition coil control circuit DTC sets if the ECM detects a fault condition in the control circuit of an ignition coil.

Conditions for Running the DTC

Run continuously once the following conditions are met:

•

The engine is running.

•

The engine speed is 480 – 5,000 rpm

•

The battery voltage is 10.0 – 16.0 V.

Conditions for Setting the DTC

DTC P0351, P0352, P0353, P0354, P0355 or P0356

The ECM detects an open circuit fault condition in the ignition coil control circuit.

DTC P2300, P2303, P2306, P2309, P2312 or P2315

The ECM detects a short to ground fault condition in the ignition coil control circuit.

DTC P2301, P2304, P2307, P2310, P2313 and P2316

The ECM detects a short to voltage fault condition in the ignition coil control circuit.

Conditions for Clearing the DTC

The ignition coil control circuit DTCs are Type B DTCs. Refer to 1.4

Diagnostic Trouble Codes in this Section, for

action taken when Type B DTC sets and conditions for clearing Type B DTCs.

Additional Information

•

Refer to 6C1-1 Engine Management – V6 – General Information for details of the ignition coil operation.

•

A short to voltage fault condition damages the ignition coil. Do not replace the ignition until this fault condition is
rectified.

•

The ignition coils for each bank of the engine are fused separately. If all DTCs for a single bank are set, there may
be a fault in one of the ignition supply circuits.

•

The ignition coils for each bank of the engine have a separate ground connections. If all DTCs for a single bank
are set, there may be a fault in one of the ground circuits.

•

For an intermittent fault condition, refer to 5.2

Intermittent Fault Conditions in this Section.

•

Since fault condition in a wiring connector may trigger DTCs, always test the connectors related to this diagnostic
procedure for shorted terminals or poor wiring connection before replacing any component. Refer to 8A Electrical -
Body and Chassis for information on electrical fault diagnosis.

•

To assist diagnosis, refer to 3 Wiring Diagrams and Connector Charts in this Section, for the system wiring
diagram and connector charts.

Test Description

The following numbers refer to the step numbers in the diagnostic table:

3

Determines if there is a fault condition in the ignition voltage supply circuit.

5

Determines if there is a fault condition in the ground circuits of the ignition coil.

6

Tests if the ECM is commanding the ignition coil on and off.

Engine Management – V6 – Diagnostics

Page 6C1-2–120

DTC P0351 to P0356, P2300, P2301, P2303, P2304, P2306, P2307, P2309, P2310, P2312,
P2313, P2315 or P2316 Diagnostic Table

Step Action

Yes

No

1

Has the Diagnostic System Check been performed?

Go to Step 2

Refer to

4.4 Diagnostic

System Check in

this Section

2

1

Switch off the ignition for 30 seconds.

2

Start the engine.

3

Using Tech 2, select the DTC display function.

Does DTC P0351, P0352, P0353, P0354, P0355, P0356, P2300,
P2301, P2303, P2304, P2306, P2037, P2309, P2310, P2312, P2313,
P2315 or P2316 fail this ignition cycle?

Go to Step 3

Refer to Additional

Information in this

DTC

3

1

Disconnect the wiring connector of the appropriate ignition coil.

2

Switch on the ignition with the engine not running.

3

Connect a test lamp between the ignition voltage circuit of the
appropriate ignition coil connector and the ECM housing.

Does the test lamp illuminate?

Go to Step 4

Go to Step 6

4

Connect a test lamp between a 12 V and each of the ground circuits
of the ignition coil connector.

Does the test lamp illuminate?

Go to Step 5

Go to Step 7

5

1

Start the engine.

2

Using a digital multimeter, measure the frequency at the control
circuit of the ignition coil.

Does the multimeter display 3 – 20 Hz?

Go to Step 9

Go to Step 8

6

Repair the high resistance or open circuit fault condition at the ignition
voltage circuit of the ignition coil. Refer to 8A Electrical - Body and
Chassis for information on electrical wiring repair procedures.

Was the repair completed?

Go to Step 11

—

7

Repair the high resistance or open circuit fault condition at the ignition
coil ground circuits. Refer to 8A Electrical - Body and Chassis for
information on electrical wiring repair procedures.

Was the repair completed?

Go to Step 11

—

8

Test the appropriate ignition coil control circuit for a high resistance,
open circuit, short to ground or short to voltage fault condition. Refer
to 8A Electrical - Body and Chassis for information on electrical fault
diagnosis.

Was any fault found and rectified?

Go to Step 11

Go to Step 10

9

A short to voltage fault condition damages the ignition
coil. Do not replace the ignition until this fault
condition is rectified.

Replace the faulty ignition coil. Refer to 6C1-3 Engine Management –
V6 – Service Operations.

Was the repair completed?

Go to Step 11

—

Engine Management – V6 – Diagnostics

Page 6C1-2–121

Step Action

Yes

No

10 Replace the ECM. Refer to 6C1-3 Engine Management – V6 –

Service Operations.

Was the repair completed?

Go to Step 11

—

11 1

Using Tech 2, clear the DTCs.

2

Switch off the ignition for 30 seconds.

3

Start the engine.

4

Operate the vehicle within the conditions for running the DTC.

Does any of the ignition coil control circuit DTCs fail this ignition
cycle?

Go to Step 2

Go to Step 12

12 Using Tech 2, select the DTC display function.

Does Tech 2 display any DTCs?

Go to the

appropriate DTC

Table in this Section

System OK

When all diagnosis and repairs are completed, check the system for correct operation.

7.23 DTC P0420 or P0430

DTC Descriptors

This diagnostic procedure supports the following DTCs:

•

DTC P0420 Catalyst System Low Efficiency Bank 1

•

DTC P0430 Catalyst System Low Efficiency Bank 2

Circuit Description

To maintain a reasonably low emission level of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen
(NOx) a 3-way catalytic converter (TWC) is used. The catalyst within the converter promotes a chemical reaction that
oxidizes the HC and CO present in the exhaust gas. This reaction converts the gases into harmless water vapour and
carbon dioxide. The catalyst also reduces the NOx, converting the NOx into nitrogen. The engine control module (ECM)
monitors this process using the post catalyst heated oxygen sensor (HO2S) signal. The post-catalyst HO2S located in
the exhaust stream after the TWC, produces an output signal that indicates the oxygen storage capacity of the catalyst.
The oxygen storage capacity (OSC) determines the ability of the catalyst to convert the exhaust emissions effectively. If
the catalyst is functioning correctly, the post-catalyst HO2S signal will be far less active than the signal produced by the
pre-catalyst HO2S.

To determine OSC, the ECM commands a rich air / fuel mixture until all oxygen is removed from the catalyst. The ECM
then commands a lean air / fuel mixture and monitors the rear heated oxygen sensors to calculate the oxygen storage
capacity. The catalyst is operated in this mode until one of the following conditions occur:

•

The oxygen stored in the catalyst exceeds a calibrated threshold, which is determined from the rear HO2S signal.

•

The rear HO2S indicates the catalyst to be completely saturated with oxygen, which is determined from the rear
HO2S signal.

If the ECM detects the average OSC is less than a threshold, this DTC sets. This indicates that the TWC oxygen
storage capacity is below a threshold considered acceptable.

Conditions for Running the DTC

•

Before the ECM can report, the following DTCs must run and pass:
DTC P0420 or P0430 failed, DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0053,
P0056, P0057, P0058, P0059, P0101, P0102, P0103, P0121, P0122, P0123, P0130, P0131, P0132, P0133,
P0135, P0137, P0138, P0139, P0140, P0141, P0150, P0151, P0152, P0153, P0155, P0157, P0158, P0159,
P0160, P0161, P0221, P0222, P0223, P0335, P0336, P0338, P167A, P167B, P2096, P2097, P2098, P2099,
P2195, P2196, P2197, P2198, P2232, P2235, P2237, P2240, P2243, P2247, P2251, P2254, P2270, P2271,
P2272, P2273, P2297, P2298, P2626, and P2629.

•

The following DTCs are not set:
DTCs P0030, P0031, P0032, P0036, P0037, P0038, P0050, P0051, P0052, P0053, P0056, P0057, P0058,
P0059, P0101, P0102, P0103, P0116, P0117, P0118, P0119, P0121, P0122, P0123, P0125, P0130, P0131,
P0132, P0133, P0135, P0137, P0138, P0139, P0140, P0141, P0150, P0151, P0152, P0153, P0155, P0157,