Isuzu N-Series. Manual - part 671

6E-106 Engine Control System (4HK1)

Turn OFF the ignition.

Connect a 3-amp fused jumper wire between
the 5 volts reference circuit and the signal
circuit of the BARO sensor harness (pins 3
and 2 of B-422 connector).

Turn ON the ignition, with the engine OFF.

Observe the BARO Sensor parameter with the
Tech 2.

Is the BARO Sensor parameter more than specified
value?

4.5 volts

Go to Step 8

Go to Step 7

Test the 5 volts reference circuit between the
engine control module (ECM) (pin 61 of J-191
connector) and the BARO sensor (pin 3 of B-
422 connector) for an open circuit or high
resistance.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 12

Go to Step 9

Test the signal circuit between the ECM (pin
71 of J-191 connector) and the BARO sensor
(pin 2 of B-422 connector) for the following
conditions:

• An open circuit
• A short to ground
• A short to the low reference circuit
• High resistance

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 12

Go to Step 9

Turn OFF the ignition.

Inspect for an intermittent and for poor
connections at the harness connector of the
BARO sensor (pins 2 and 3 of B-422
connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 12

Go to Step 10

Turn OFF the ignition.

Disconnect the ECM harness connector.

Inspect for an intermittent and for poor
connections on the BARO sensor circuits at
the harness connector of the ECM (pins 61
and 71 of J-191 connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 12

Go to Step 11

Replace the BARO sensor. Refer to Barometric
Pressure (BARO) Sensor Replacement in this
section.

Did you complete the replacement?

—

Go to Step 12

—

Important:
Replacement ECM must be programmed.

Replace the ECM. Refer to Engine Control Module
(ECM) Replacement / Fuel Injector ID Code Data
Programming in this section.

Did you complete the replacement?

—

Go to Step 12

—

Step

Action

Value(s)

Yes

Engine Control System (4HK1) 6E-107

Reconnect all previously disconnected
harness connector(s).

Clear the DTCs with the Tech 2.

Turn OFF the ignition for 30 seconds.

Start the engine.

Operate the vehicle within the Conditions for
Running the DTC.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 13

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

Step

Action

Value(s)

Yes

6E-108 Engine Control System (4HK1)

P0108 (Flash Code 71)

Circuit Description
The barometric pressure (BARO) sensor is located
under the instrument panel cluster (IPC) near the pedal
bracket. The BARO sensor is a transducer that varies
voltage according to the barometric pressure changes
and the generated voltage is input to the engine control
module (ECM) for the BARO signal. The BARO sensor
has the following circuits.

• 5 volts reference circuit.
• Low reference circuit.
• BARO sensor signal circuit.

The ECM supplies 5 volts to the BARO sensor on the 5
volts reference circuit. The ECM also provides a ground
on the low reference circuit. The BARO sensor
provides a signal to the ECM on the BARO signal
circuit, which is relative to the pressure changes
barometric pressure. The ECM should detect a low
signal voltage at a low barometric pressure, such as
high altitude place. The ECM should detect high signal
voltage at a high barometric pressure. 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

• DTCs P1630 and P1632 are not set.
• The ignition switch is ON.
• The ignition voltage is more than 18 volts.

Condition for Setting the DTC

• The ECM detects that the BARO sensor signal

voltage is more than 4.9 volts for 10 seconds.

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 75 kPa (11

psi) for engine control.

• The ECM inhibits EGR valve control.

Condition for Clearing the MIL / DTC

• The ECM turns OFF the MIL when the key is

cycled after a current DTC clears.

• A current DTC clears when the diagnostic runs and

does not fail.

• A history DTC clears after 20 consecutive driving

cycles without a fault. Or clear with the Tech 2 or
accelerator pedal operation.

Diagnostic Aid

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

DTC P0108 (Flash Code 71)
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.

Turn ON the ignition, with the engine OFF.

Observe the Barometric Pressure (BARO)
Sensor parameter with the Tech 2.

Is the BARO Sensor parameter more than the
specified value?

4.9 volts

Go to Step 3

Go to Diagnostic

Aids

Turn ON the ignition, with the engine OFF.

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

Is DTC P1632 also set?

—

Go to Step 4

Go to Step 5

Turn OFF the ignition.

Disconnect the BARO sensor harness
connector.

Turn ON the ignition, with the engine OFF.

Observe the BARO Sensor parameter with the
Tech 2.

Is the BARO Sensor parameter less than the
specified value?

0.5 volts

Go to DTC P1632

Go to Step 7

Engine Control System (4HK1) 6E-109

Turn OFF the ignition.

Disconnect the BARO sensor harness
connector.

Turn ON the ignition, with the engine OFF.

Observe the BARO Sensor parameter with the
Tech 2.

Is the BARO Sensor parameter less than the
specified value?

0.5 volts

Go to Step 6

Go to Step 7

Turn OFF the ignition.

Connect a test lamp between the low
reference circuit of the BARO sensor harness
(pin 1 of B-422 connector) and battery voltage.

Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

—

Go to Step 9

Go to Step 8

Important:
The BARO sensor may be damaged if the sensor
signal circuit is shorted to a voltage source.

Test the signal circuit between the engine
control module (ECM) (pin 71 of J-191
connector) and the BARO sensor (pin 2 of B-
422 connector) for the following conditions:

• A short to battery or ignition voltage
• A short to any 5 volts reference

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 12

Test the low reference circuit between the
ECM (pin 60 of J-191 connector) and the
BARO sensor (pin 1 of B-422 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

Turn OFF the ignition.

Inspect for an intermittent and for a poor
connection at the harness connector of the
BARO sensor (pin 1 of B-422 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 BARO sensor circuit at the
harness connector of the ECM (pin 60 of J-
191 connector).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 12

Replace the BARO sensor. Refer to Barometric
Pressure (BARO) Sensor Replacement in this
section.

Did you complete the replacement?

—

Go to Step 13

—

Step

Action

Value(s)

Yes

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