Isuzu KB P190. Manual - part 1467

IMMOBILIZER CONTROL SYSTEM (4JK1/4JJ1/HFV6)   11A-17

10

Notice: If no automatic transmission is installed,
skip to Step 11.

1.

Turn OFF the ignition.

2.

Reconnect the ECM C-56 and E-90 harness
connectors.

3.

Disconnect the TCM C-96 harness connector.

4.

Turn ON the ignition, with the engine OFF.

5.

Attempt to communicate with the PIM and
ICU.

Does the scan tool communicate with the PIM and
ICU?

—

Go to Step 13

Go to Step 11

11

1.

Turn OFF the ignition.

2.

Reconnect the ECM C-56 and E-90 harness
connectors if disconnected.

3.

Reconnect the TCM C-96 harness connector
if disconnected.

4.

Disconnect the PIM B-96 and B-97 harness
connectors.

5.

Turn ON the ignition, with the engine OFF.

6.

Attempt to communicate with the ICU.

Does the scan tool communicate with the ICU?

—

Go to Step 14

Go to Step 12

12

1.

Turn OFF the ignition.

2.

Reconnect the PIM B-96 and B-97 harness
connectors.

3.

Disconnect the ICU B-109 harness connector.

4.

Turn ON the ignition, with the engine OFF.

5.

Attempt to communicate with the ECM, TCM
and PIM.

Does the scan tool communicate with the ECM,
TCM and PIM?

—

Go to Step 19

Go to Step 15

13

1.

Test the CAN Low and High circuits between
the ECM (pins 23 and 55 of C-56) and the
TCM (pins 6 and 7 of C-96) for the following
conditions:

• A short to ground

• A short to battery or ignition voltage

• A short circuit each other

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 20

Go to Step 17

14

1.

Test the CAN Low and High circuits between
the PIM (pins 7 and 9 of B-97) and the TCM
(pins 37 and 38 of C-96) or ECM (pins 23 and
55 of C-56) for the following conditions:

• A short to ground

• A short to battery or ignition voltage

• A short circuit each other

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 20

Go to Step 18

Step

Action

Value(s)

Yes

No

11A-18   IMMOBILIZER CONTROL SYSTEM (4JK1/4JJ1/HFV6)

15

Repair the open circuit, short to ground, short to
voltage or short circuit each other on the CAN Low
or High circuits between the DLC and PIM or ICU.

Did you complete the repair?

—

Go to Step 20

—

16

Important: Replacement ECM must be
programmed and learned.

Replace the ECM. Refer to ECM Replacement.

Did you complete the replacement?

—

Go to Step 20

—

17

Important: Replacement TCM must be
programmed.

Replace the TCM. Refer to ECM Replacement.

Did you complete the replacement?

—

Go to Step 20

—

18

Important: Replacement PIM must be
programmed.

Replace the PIM. Refer to PIM Replacement.

Did you complete the replacement?

—

Go to Step 20

—

19

Important: Replacement ICU must be
programmed.

Replace the ICU. Refer to ICU Replacement.

Did you complete the replacement?

—

Go to Step 20

—

20

Attempt to establish communication with the ICU,
ECM, TCM and PIM.

Does the scan tool communicate with the ICU,
ECM, TCM and PIM?

—

System OK

Go to Step 2

Step

Action

Value(s)

Yes

No

IMMOBILIZER CONTROL SYSTEM (4JK1/4JJ1/HFV6)   11A-19

Lost Communication with The Immobilizer Control Unit (ICU)

Circuit Description

The engine control module (ECM), transmission control
module (TCM) (AISIN A/T only) and ICU all
communicate with the scan tool over the controller area
network (CAN) link. The ECM, TCM, ICU and the data
recording module (DRM) communicate with each other
over the same CAN link. (4JK1/ 4JJ1)

The ECM, TCM, powertrain interface module (PIM) and
ICU all communicate with the scan tool over the CAN
link. (HFV6)

Schematic Reference: Immobilizer Controls
Schematics

Connector End View Reference: ICU Connector End
View

Circuit/ System Testing Lost Communication with The Immobilizer Control Unit (ICU)

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check -
Immobilizer Controls?

—

Go to Step 2

Go to Diagnostic 

System Check - 

Immobilizer 

Controls

2

Attempt to establish communication with the ICU.

Does the scan tool communicate with the ICU?

—

Go to Intermittent 

Conditions

Go to Step 3

3

1.

Turn OFF the ignition.

2.

Disconnect the scan tool from the data link
connector (DLC) if connected.

3.

Measure the resistance across the CAN Low
and High circuits by probing the DLC (pins 6
and 14 of B-58).

Is the resistance within the specified value (parallel
resistance of the 120

Ω resistor in the ECM and the

120

Ω resistor in the ICU should be 60Ω)?

50 to 70 

Ω

Go to Step 5

Go to Step 4

4

1.

Test the CAN Low and High circuits between
the ICU (pins 5 and 6 of B-109) and the data
link connector (DLC) (pins 6 and 14 of B-58)
for an open circuit or high resistance.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 11

Go to Step 9

5

1.

Turn OFF the ignition.

2.

Disconnect the ICU harness connector.

3.

Connect a test lamp between the battery
voltage feed circuit  (pin 1 of B-109) and a
known good ground.

Does the test lamp illuminate?

—

Go to Step 6

Go to Step 7

6

Connect a test lamp across the battery voltage feed
circuit and the ground circuit (pins 1 and 3 of B-
109)

Does the test lamp illuminate?

—

Go to Step 9

Go to Step 8

7

Repair the open circuit or high resistance between
the Meter (+B) (10A) fuse and the ICU (pin 1 of B-
109).

Did you complete the repair?

—

Go to Step 11

—

8

Repair the open circuit or high resistance between
the ICU (pin 3 of B-109) and ground terminal.

Did you complete the repair?

—

Go to Step 11

—

11A-20   IMMOBILIZER CONTROL SYSTEM (4JK1/4JJ1/HFV6)

9

1.

Turn OFF the ignition.

2.

Disconnect the ICU harness connector.

3.

Inspect for an intermittent, for poor
connections and for corrosion at the harness
connector of the ICU (pins 1, 3, 5 and 6 of B-
109)

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 11

Go to Step 10

10

Important: Replacement ICU must be
programmed.
Replace the ICU.  Refer to ICU Replacement.

Did you complete the replacement?

—

Go to Step 11

—

11

1.

Turn OFF the ignition.

2.

Reconnect all previously disconnected fuse or
harness connector(s).

3.

Turn the ignition ON, with the engine OFF.

4.

Attempt to establish communication with the
ICU.

Does the scan tool communicate with the ICU?

—

System OK

Go to Step 3

Step

Action

Value(s)

Yes

No