Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual - part 82

4JA1-TC/4JH1-TC ENGINE DRIVEABILITY AND EMISSIONS

6E–323

15

Check any accessory parts which may cause electric
interference.
Was the problem found?

—

Remove the 

accessory parts 
and verify repair

Go to Step 16

16

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 17

17

Substitute a known good ECM and recheck. 
Was the problem solved? 
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.  

—

Go to Step 18

Go to Step 19

18

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

—

19

Replace the injection pump assembly. 
Is the action complete?

—

Verify repair

—

Step

Action

Value(s)

Yes

No

6E–324

4JA1-TC/4JH1-TC ENGINE DRIVEABILITY AND EMISSIONS

DIAGNOSTIC TROUBLE CODE (DTC) P1690 (SYMPTOM CODE 4) 

(FLASH CODE 77) CHECK ENGINE LAMP (MIL) CIRCUIT VOLTAGE LOW

DIAGNOSTIC TROUBLE CODE (DTC) P1690 (SYMPTOM CODE 8) 

(FLASH CODE 77) CHECK ENGINE LAMP (MIL) CIRCUIT VOLTAGE HIGH

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

Circuit Description

The Check Engine Lamp (Malfunction Indicator Lamp
=MIL) should always be illuminated and steady with
ignition  “On”. Ignition feed voltage is supplied to the
Check Engine Lamp bulb through the meter fuse. The
ECM turns the Check Engine Lamp “On” by grounding
the check engine lamp driver circuit for a certain time.

Diagnostic Aids

An intermittent may be caused by the following:

• Poor connections.

• Misrouted harness.

• Rubbed through wire insulation.

• Broken wire inside the insulation.

Flash 

Code

Code

Symptom 

Code

MIL

DTC Name

DTC Setting Condition

Fail-Safe (Back Up)

77

P1690

4

OFF

Check Engine Lamp (MIL) 
Circuit Voltage Low

Check engine lamp circuit 
open or short to ground cir-
cuit.

No fail-safe function.

8

OFF

Check Engine Lamp (MIL) 
Circuit Voltage High

Check engine lamp circuit 
short to ground circuit.

Ignition
SW

Meter
15A

6 15

7

Batt

Batt

0.5
RED/
WHT

29

0.5
ORG/
BLU

43

0.5
BRN/
YEL

42

0.5
BLK/
RED

27

0.5
BLU/
WHT

0.5 BLU/BLK

68

0.5
WHT

2.0
BLK

35

VSS

0.85
YEL

Imnobiliser

Control Unit

7

8

0.5
BRN/
YEL

IC

0.85
YEL

Glow

Check

Engine

Tacho

Meter

Speed

Meter

A/T

TCM

µP

µP

µP

µP

Engine
Control
Module
(ECM)

4JA1-TC/4JH1-TC ENGINE DRIVEABILITY AND EMISSIONS

6E–325

Check for the following conditions:

• Poor connection at ECM-Inspect harness connectors

for backed out terminals, improper mating, broken
locks, improperly formed or damaged terminals, and
poor terminal to wire connection.

• Damaged harness-Inspect the wiring harness for

damage. If the harness appears to be OK, observe
the “Check Engine Lamp” display on the Tech2 while
moving connectors and wiring harnesses. A change
in the display will indicate the location of the fault.

Diagnostic Trouble Code (DTC) P1690 (Symptom Code 4) (Flash Code 77) 

Check Engine Lamp (MIL) Circuit Voltage Low

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 P1690 (Symptom Code 4) stored as
“Present Failure”?

—

Go to Step 3

Refer to 

Diagnostic Aids 

and Go to Step 

3

3

1. Using the Tech 2, ignition “On” and engine “Off”. 

2. Select  “F1: Clear DTC Information” in “F0:

Diagnostic Trouble Codes” with the Tech 2 and
clear the DTC information. 

3. Operate the vehicle and monitor the “F0: Read

DTC Infor As Stored By ECU” in the “F0:
Diagnostic Trouble Codes”. 

Was the DTC P1690 (Symptom Code 4) stored in this
ignition cycle?

—

Go to Step 4

Refer to 

Diagnostic Aids 

and Go to Step 

4

4

1. Ignition “On”, engine “Off”. 

2. Check the “Check Engine” lamp. 

Does the lamp turn “On”?

—

Go to Step 5

Go to Step 6

5

1. Ignition “On”, engine “Off”. 

2. Check the “Check Engine” lamp. 

Does the lamp turn “Off”?

—

Go to Step 9

Go to Step 7

6

Check the “Check Engine” lamp bulb. 
If the bulb is burnt out, repair as necessary. 
Was the problem found?

—

Verify repair

Go to Step 7

6E–326

4JA1-TC/4JH1-TC ENGINE DRIVEABILITY AND EMISSIONS

7

Check for poor/faulty connection at the meter
connector and ECM connector. If a poor/faulty
connection is found, repair as necessary. 
Was the problem found?

—

Verify repair

Go to Step 8

Step

Action

Value(s)

Yes

No

2

6

42

C-56

B-23

4JA1-TC

B-23

4JH1-TC