Isuzu KB P190. Manual — part 860

Engine Management – V6 – Diagnostics

Page 6C1-2–162

Conditions for Clearing the DTC

The clutch switch circuit DTC is a Type C DTC. Refer to 1.4

Diagnostic Trouble Codes in this Section, for action

taken when Type C DTCs set and conditions for clearing Type C DTCs.

Additional Information

•

For an intermittent fault condition, refer to 5.2

Intermittent Fault Conditions in this Section.

•

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

•

Refer to 8C Cruise Control for clutch pedal switch operation and testing.

•

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.

DTC P0704 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

Operate the vehicle within the conditions for running the DTC.

3

Using Tech 2, select the DTC display function.

Does DTC P0704 fail this ignition cycle?

Go to Step 3

Refer to Additional

Information in this

DTC

3

1

Switch on the ignition with the engine not running.

2

On Tech 2 select: Engine / V6 Engine / Data Display / Engine
Data 1.

3

Observe the status of the cruise control cancel switch.

4

Depress the clutch pedal.

Does Tech 2 display change from Inactive to Active when the pedal is
pressed?

Refer to Additional

Information in this

DTC

Go to Step 4

4

1

Disconnect the wiring connector from the cruise control cancel
switch. Refer to 8C Cruise Control – HFV6.

2

Switch on the ignition.

3

Connect a test lamp between the voltage circuit of cruise control
cancel clutch switch and a ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 5

5

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

Was the repair completed?

Go to Step 9

—

6

Test the cruise control cancel clutch switch. Refer to 8C Cruise
Control – HFV6.

Was any fault found and rectified?

Go to Step 9

Go to Step 7

Engine Management – V6 – Diagnostics

Page 6C1-2–163

7

Test the control circuit of the cruise control clutch switch, which failed
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 9

Go to Step 8

8

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

Was the repair completed?

Go to Step 9

—

9

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 DTC P0704 fail this ignition cycle?

Go to Step 2

Go to Step 11

10 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.

7.42 DTC

P0850

DTC Descriptor

This diagnostic procedure supports DTC P0850 – Park / Neutral Signal Circuit Incorrect Signal.

Circuit Description

The Park / Neutral (P / N) switch is a part of the automatic transmission gear selector position switch assembly.

The P / N switch is a normally open switch that closes when the transmission is shifted to Park or Neutral position. The
ECM applies a reference 12 V to the signal circuit of the P / N switch when it is open. When the transmission is shifted
to the Park or Neutral position, the P / N switch closes and pulls the P/ N switch signal circuit to ground.

DTC P0850 sets when the ECM detects a fault condition in the P / N switch circuit.

Conditions for Running the DTC

DTC P0850 runs continuously when the ignition voltage is 10.0 – 16.0 V.

Conditions for Setting the DTC

DTC P0850 sets when the ECM detects one of the following fault conditions:

•

The P / N switch signal circuit is pulled to ground for 100 seconds while the TCM sends a signal that the
transmission is in gear.

•

The P / N switch signal circuit is 12 V for 100 seconds while the TCM sends a signal the transmission is in park or
neutral.

Conditions for Clearing the DTC

DTC P0850 is a Type ‘C’ DTC. Refer to 1.4 Diagnostic Trouble Codes in this Section, for action taken when Type ‘C’
DTCs set and conditions for clearing Type ‘C’ DTCs.

Additional Information

•

The ECM uses the transmission range data to enable engine cranking when DTC P0850 sets.

•

For an intermittent fault condition, refer to 5.2

Intermittent Fault Conditions in this Section.

•

Refer to 6C1-1 Engine Management – V6 – General Information for details of the park / neutral switch operation.

Engine Management – V6 – Diagnostics

Page 6C1-2–164

•

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.

DTC P0850 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 on the ignition.

2

Using Tech 2, observe the status of the automatic transmission
gear position.

3

Shift the transmission lever across all gear levels.

Does Tech 2 display P/N when the transmission is in park or neutral
and In Gear when the transmission lever is in other positions?

Go to Step 3

Go to Step 4

3

1

Switch off the ignition for 30 seconds.

2

Switch on the ignition.

3

Shift the transmission lever across all gear levels.

Does DTC P0850 fail this ignition cycle?

Go to Step 4

Refer to Additional

Information in this

DTC

4

1

Remove the transmission position switch wiring connector.
Refer to 7C4 Automatic Transmission_4L60E – On-vehicle
Servicing.

2

Connect a test lamp between the ground circuit of the
transmission switch and a 12 V source.

Does the test lamp illuminate?

Go to Step 5

Go to Step 6

5

1

Connect a 3 A jumper wire between the signal circuit of the
park / neutral signal circuit and a good ground.

2

Using Tech 2, observe the status of the transmission gear.

Does Tech 2 display a change from In Gear to P/N when the jumper
wire is connected?

Go to Step 8

Go to Step 7

6

Repair the high resistance or open circuit fault condition in the ground
circuit of the transmission position switch. Refer to 8A Electrical -
Body and Chassis for information on electrical wiring repair
procedures.

Was the repair completed?

Go to Step 10

—

7

Test the signal circuit of the park / neutral switch 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 10

Go to Step 9

8

Replace the transmission position switch. Refer to 7C4 Automatic
Transmission – 4L60E – On-vehicle Servicing.

Was the repair completed?

Go to Step 10

—

9

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

Was the repair completed?

Go to Step 10

—

Engine Management – V6 – Diagnostics

Page 6C1-2–165

Step Action

Yes

No

10 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 DTC P0850 fail this ignition cycle?

Go to Step 2

Go to Step 11

11 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.

7.43 DTC

P1648

DTC Descriptor

This diagnostic procedure supports DTC P1648 – Wrong Security Code Entered.

Circuit Description

Tech 2 is used to program the engine control module (ECM). Before any programming, a security code must be entered
into Tech 2. The ECM will check if the code entered is correct before continuing. If the security code is incorrect, DTC
P1648 sets.

Conditions for Running the DTC

Conditions for running the DTC are:

•

The ignition is switched on.

•

The ignition voltage is 10.0 – 16.0 V.

Conditions for Setting the DTC

An incorrect security code is entered into Tech 2 when attempting to program the ECM.

Action Taken When the DTC Sets

When the DTC sets, the malfunction indicator lamp (MIL) is not displayed.

Conditions for Clearing the DTC

The immobiliser security code is a Type ‘C’ DTC. Refer to 1.4 Diagnostic Trouble Codes in this Section, for action
taken when a Type ‘C’ DTC sets and conditions for clearing Type ‘C’ DTCs.

Additional Information

•

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

•

Refer to 6C1-3 Engine Management –V6 – Service Operations for details on resetting the ECM.

•

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.

•

For an intermittent fault condition, refer to 5.2

Intermittent Fault Conditions in this Section.

•

To assist diagnosis, refer to 3

Wiring Diagrams and Connector Charts in this Section, for the system wiring

diagram and connector charts.