Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 163

6E–256

4JH1 ENGINE DRIVEABILITY AND EMISSIONS

5

Using the DVM and check the neutral switch (inhibitor
switch). 

1. Ignition “Off”, engine “Off”. 

2. Remove the neutral switch connector (inhibitor

switch connector) at the transmission. 

3. Check the neutral switch (P range  N range

switch). 

Was the DVM indicated specified value?

Neutral (P or 

N): Continuity

Other than 

neutral (P or 

N): No 

continuity Go 

to 

Step 6

Replace neutral 

switch (inhibitor 

switch) and 

verify repair

6

Using the DVM and check the neutral switch (inhibitor
switch) power supply circuit. 

1. Ignition “On”, engine “Off”. 

2. Remove the neutral switch (inhibitor switch)

connector from the switch. 

3. Check the circuit for open circuit. 

Was the DVM indicated specified value?

Battery 
voltage

Go to Step 8

Go to Step 7

7

Repair the open circuit between the “ECM fuse (10A)”
and neutral switch (between the “Back Up fuse (15A)”
and inhibitor switch). 
Is the action complete?

—

Verify repair

—

Step

Action

Value(s)

Yes

No

E-11

E-12

M/T

1

2

3

6

5

4

7

8

10

9

8

3

2

A/T

V

E-12

M/T

V

3

E-51

A/T

4JH1 ENGINE DRIVEABILITY AND EMISSIONS

6E–257

8

Using the DVM and check the neutral switch (inhibitor
switch) circuit. 
Breaker box is available: 

1. Ignition “Off”, engine “Off”. 

2. Install the breaker box as type B. (ECM

connected) Ref. Page 6E-73 

3. Ignition “On”, engine “Off”. 

4. Check the circuit for open or short to voltage

circuit. 

Was the DVM indicated specified value?

Breaker box is not available: 

1. Ignition “On”, engine “Off”. 

2. Back probe the DVM to the neutral switch (inhibitor

switch) and check the circuit for open or short to
voltage circuit. 

Was the DVM indicated specified value?

Neutral (P or 

N): Battery 

voltage

Other than 

neutral (P or 

N): Less than 

1V Go 

to 

Step 11

Fixed at battery 

voltage: Go to 

Step 9

Fixed at less 

than 1V: Go to 

Step 10

9

Repair the short to voltage circuit between the neutral
switch connector (inhibitor switch connector) and
ECM. 
Is the action complete?

—

Verify repair

—

Step

Action

Value(s)

Yes

No

87

V

V

8

2

V

V

E-11

E-51

M/T

A/T

87

87

8

2

C-57

C-57

M/T

A/T

E-11

E-51

6E–258

4JH1 ENGINE DRIVEABILITY AND EMISSIONS

10

Repair the open circuit between the neutral switch
connector (inhibitor switch connector) and ECM. 
Is the action complete?

—

Verify repair

—

11

Is the ECM programmed with the latest software
release? 
If not, download the latest software to the ECM using
the “SPS (Service Programming System)”. 
Was the problem solved?

—

Verify repair

Go to Step 12

12

Replace the ECM. 
Is the action complete? 
IMPORTANT: The replacement ECM must be
programmed. Refer to section of the Service
Programming System (SPS) in this manual. 
Following ECM programming, the immobiliser system
(if equipped) must be linked to the ECM. Refer to
section 11 “Immobiliser System-ECM replacement” for
the ECM/Immobiliser linking procedure.

—

Verify repair

—

Step

Action

Value(s)

Yes

No

87

87

8

2

C-57

C-57

M/T

A/T

E-11

E-51

4JH1 ENGINE DRIVEABILITY AND EMISSIONS

6E–259

DIAGNOSTIC TROUBLE CODE (DTC) P1605 (SYMPTOM CODE C) 

(FLASH CODE 55) SEED AND KEY FILE DESTROYED

DIAGNOSTIC TROUBLE CODE (DTC) P1605 (SYMPTOM CODE D) 

(FLASH CODE 55) EEPROM DEFECT

DIAGNOSTIC TROUBLE CODE (DTC) P1605 (SYMPTOM CODE E) 

(FLASH CODE 55) EEPROM DEFECT

Condition for setting the DTC and action taken when the DTC sets

Circuit Description & Diagnostic Aids

The ECM used in this vehicle utilizes an electrically
erasable & programmable read only memory
(EEPROM). The EEPROM contains program
information and the calibrations required for engine and

diagnostics operation. 
If the ECM inside (IC, circuit, memory, etc,) failed, DTC
P1605 (Symptom Code C), P1605 (Symptom Code D)
or P1605 (Symptom Code E) will be stored.

Diagnostic Trouble Code (DTC) P1605 (Symptom Code C) (Flash Code 55) 

Seed and Key File Destroyed

Diagnostic Trouble Code (DTC) P1605 (Symptom Code D) (Flash Code 55) 

EEPROM Defect

Diagnostic Trouble Code (DTC) P1605 (Symptom Code E) (Flash Code 55) 

EEPROM Defect

Flash 

Code

Code

Symptom 

Code

MIL

DTC Name

DTC Setting Condition

Fail-Safe (Back Up)

55

P1605

C

ON

Seed and Key File Destroyed

Seed or key file in EEPROM 
is destroyed.

No fail-safe function.

D

ON

EEPROM Defect

Write and read from the 
EEPROM are failed during ini-
tialization of the ECM.

ECM uses default values from 
the EPROM.

E

ON

EEPROM Defect

EEPROM checksum does not 
match with the read check 
sum during initialization of the 
ECM.

Step

Action

Value(s)

Yes

No

1

Was  the  “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to Step 2

Go to On Board 

Diagnostic 

(OBD) System 

Check

2

1. Connect the Tech 2. 

2. Review and record the failure information. 

3. Select “F0: Read DTC Infor As Stored By ECU” in

“F0: Diagnostic Trouble Codes”. 

Is the DTC P1605 (Symptom Code C), P1605
(Symptom Code D) or P1605 (Symptom Code E)
stored as “Present Failure”?

—

Go to Step 3

Refer to 

Diagnostic Aids 

and Go to Step 

3