Isuzu N-Series. Service manual - part 777

Engine Control System (4JH1) 6E-159

P1105 (Symptom Code 1) (Flash Code 86)

Circuit Description
The barometric pressure (BARO) sensor is installed
inside of the engine control module (ECM) and
converts the BARO into a voltage signal. The ECM
uses this voltage signal to calibrate the fuel injection
quantity and injection timing for altitude compensation.
If the ECM detects an excessively high BARO sensor
signal voltage, this DTC will set.

Condition for Running the DTC

• The ignition switch is ON.

Condition for Setting the DTC

• The ECM detects that the BARO sensor signal

voltage is more than 4.4 volts for 1 second.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM uses a BARO substitution of 1013 hPa.

Condition for Clearing the MIL/DTC

• The ECM turns OFF the MIL when the diagnostic

runs and does not fail.

• A history DTC clears after 40 consecutive driving

cycles without a fault. Or clear with the Tech 2.

DTC P1105 (Symptom Code 1) (Flash Code 86)

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check –
Engine Controls?

—

Go to Step 2

Go to Diagnostic

System Check –

Engine Controls

Install the Tech 2.

Turn OFF the ignition for 30 seconds.

Start the engine.

Monitor the Diagnostic Trouble Code (DTC)
Information with the Tech 2.

Does the DTC fail this ignition?

—

Go to Step 3

Go to Step 4

Important:
Replacement ECM must be programmed.

Replace the ECM. Refer to Engine Control Module
(ECM) Replacement in this section.

Did you complete the replacement?

—

Go to Step 4

—

Clear the DTCs with the Tech 2.

Turn OFF the ignition for 30 seconds.

Start the engine.

Monitor the DTC Information with the Tech 2.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 5

Observe the DTC Information with the Tech 2.

Are there any DTCs that you have not diagnosed?

—

Go to Diagnostic

Trouble Code (DTC)

List

System OK

6E-160 Engine Control System (4JH1)

P1105 (Symptom Code 2) (Flash Code 86)

Condition for Running the DTC

• The ignition switch is ON.

Condition for Setting the DTC

• The ECM detects that the BARO sensor signal

voltage is less than 1.5 volts for 1 second.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

• The ECM uses a BARO substitution of 1013 hPa.

Condition for Clearing the MIL/DTC

• The ECM turns OFF the MIL when the diagnostic

runs and does not fail.

• A history DTC clears after 40 consecutive driving

cycles without a fault. Or clear with the Tech 2.

DTC P1105 (Symptom Code 2) (Flash Code 86)

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check –
Engine Controls?

—

Go to Step 2

Go to Diagnostic

System Check –

Engine Controls

Install the Tech 2.

Turn OFF the ignition for 30 seconds.

Start the engine.

Monitor the Diagnostic Trouble Code (DTC)
Information with the Tech 2.

Does the DTC fail this ignition?

—

Go to Step 3

Go to Step 4

Important:
Replacement ECM must be programmed.

Replace the ECM. Refer to Engine Control Module
(ECM) Replacement in this section.

Did you complete the replacement?

—

Go to Step 4

—

Clear the DTCs with the Tech 2.

Turn OFF the ignition for 30 seconds.

Start the engine.

Monitor the DTC Information with the Tech 2.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 5

Observe the DTC Information with the Tech 2.

Are there any DTCs that you have not diagnosed?

—

Go to Diagnostic

Trouble Code (DTC)

List

System OK

Engine Control System (4JH1) 6E-161

P1110 (Symptom Code 4) (Flash Code 72)

Circuit Description
The engine control module (ECM) controls the exhaust
brake which energizes the intake throttle solenoid valve
and exhaust brake solenoid valve based on vehicle
running condition. The ECM commands each solenoid
valve to close each throttle valve by applying vacuum.
If the ECM detects that an open circuit or short to
ground on the intake throttle solenoid valve control
circuit, this DTC will set.

Condition for Running the DTC

• The ignition switch is ON.

Condition for Setting the DTC

• The ECM detects a low voltage condition on the

intake throttle solenoid valve control circuit for
longer than 3 seconds when the solenoid valve is
commanded OFF.

Action Taken When the DTC Sets

• The ECM illuminates the malfunction indicator

lamp (MIL) when the diagnostic runs and fails.

Condition for Clearing the MIL/DTC

• The ECM turns OFF the MIL when the diagnostic

runs and does not fail.

• A history DTC clears after 40 consecutive driving

cycles without a fault. Or clear with the Tech 2.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Test Description
The number below refers to the step number on the
diagnostic table.
5. If the intake throttle solenoid valve control circuit
between the ECM and the solenoid valve is normal,
voltage level high DTC P1110 (Symptom Code 8) will
set.

DTC P1110 (Symptom Code 4) (Flash Code 72)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check –
Engine Controls?

—

Go to Step 2

Go to Diagnostic

System Check –

Engine Controls

Install the Tech 2.

Turn OFF the ignition for 30 seconds.

Start the engine.

Monitor the Diagnostic Trouble Code (DTC)
Information with the Tech 2.

Does the DTC fail this ignition?

—

Go to Step 3

Go to Diagnostic

Aids

Turn OFF the ignition.

Disconnect the intake throttle solenoid valve
harness connector.

Connect a test lamp between the voltage feed
circuit of the intake throttle solenoid valve
harness (pin 1 of J-40 connector) and a known
good ground.

Does the test lamp illuminate?

—

Go to Step 4

Go to Step 6

Turn OFF the ignition.

Connect a test lamp between the control
circuit of the intake throttle solenoid valve
harness (pin 2 of J-40 connector) and battery
voltage.

Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

—

Go to Step 8

Go to Step 5

6E-162 Engine Control System (4JH1)

Connect a 3-amp fused jumper wire across
the intake throttle solenoid valve harness
connector between pins 1 and 2 of the J-40
connector.

Lift the driving wheels or drive the vehicle.

Let the vehicle run so that the exhaust brake
may operate while observing the Intake
Throttle Solenoid Command parameter with
the Tech 2.

Does DTC P1110 (Symptom Code 8) set when the
exhaust brake is operating, but not DTC P1110
(Symptom Code 4)?

—

Go to Step 9

Go to Step 7

Repair the open circuit or high resistance on the
voltage feed circuit between the ECM main relay
(pin 5 of X-14 connector) and the intake throttle
solenoid valve (pin 1 of J-40 connector).

Did you complete the repair?

—

Go to Step 13

—

Test the control circuit between the engine
control module (ECM) (pin 95 of B-233
connector) and the intake throttle solenoid
valve (pin 2 of J-40 connector) for an open
circuit or high resistance.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 10

Test the control circuit between the ECM (pin
95 of B-233 connector) and the intake throttle
solenoid valve (pin 2 of J-40 connector) for a
short to ground.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 12

Turn OFF the ignition.

Disconnect the intake throttle solenoid valve
harness connector.

Inspect for an intermittent and for poor
connections at the harness connector of the
intake throttle solenoid valve (pins 1 and 2 of
J-40 connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 11

Turn OFF the ignition.

Disconnect the ECM harness connector.

Inspect for an intermittent and for a poor
connection on the intake throttle solenoid
valve control circuit at the harness connector
of the ECM (pin 95 of B-233 connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 12

Replace the intake throttle solenoid valve. Refer to
Intake Throttle Solenoid Valve Replacement in this
section.

Did you complete the replacement?

—

Go to Step 13

—

Step

Action

Value(s)

Yes

Content .. 775 776 777 778 ..