Isuzu D-Max / Isuzu Rodeo (TFR/TFS). Manual — part 57

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

6E–223

DIAGNOSTIC TROUBLE CODE (DTC) P0703 (SYMPTOM CODE A)

(FLASH CODE 25) BRAKE SWITCH MALFUNCTION

DIAGNOSTIC TROUBLE CODE (DTC) P0703 (SYMPTOM CODE B)

(FLASH CODE 25) BRAKE SWITCH MALFUNCTION

Battery
Voltage

Battery
Voltage

ECM
Main Relay

Stop
Light
10A

Injection
Pump

Stop
Lamp

IC

IC

CPU

0.5
BLU/
BLK

58

2.0
BLU/
RED

0.5
BLU/
RED

3

0.5
WHT/
BLK

65

0.85
RED

0.85
RED

0.85
GRN

30

0.5
BLU/
RED
63

0.5
YEL

31

0.5
RED/
BLK

0.5
BLU/
RED

0.5
BLU/
RED

0.85
WHT

0.5
WHT/
RED

0.5
RED/
GRN

Clutch
SW

Resister

Neutral
SW

87

0.5
BLU/
YEL

39

Brake
SW

M/T

A/T

Inhibitor
SW

Ignition
SW

Back,
Turn
15A

Engine
15A

µP

N

P

Engine
Control
Module
(ECM)

Batt

Batt

6E–224

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

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

Circuit Description

The ECM monitors the brake switch signal on the feed
terminal to the ECM. If brake switch 1 or 2 circuit with
malfunction, DTC P0703 (Symptom Code A) or P0703
(Symptom Code B) will be stored.

Diagnostic Aids

An intermittent may be caused by the following:

• Poor connections.

• Misrouted harness.

• Rubbed through wire insulation.

• Broken wire inside the insulation.
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 “Brake Switch 1” and “Brake Switch 2” display on
the Tech2 while moving connectors and wiring
harness related to the sensor.

Diagnostic Trouble Code (DTC) P0703 (Symptom Code A) (Flash Code 25)

Brake Switch Malfunction

Flash

Code

Code

Symptom

Code

MIL

DTC Name

DTC Setting Condition

Fail-Safe (Back Up)

25

P0703

A

ON

Brake Switch Malfunction

1. Throttle position is more

than 0%.

2. Engine speed is more than

693rpm (4JA1-TC) or
665rpm (4JH1-TC).

3. Vehicle speed is more than

0km/h.

4. Brake switch 1 signal and

brake switch 2 signal are
differently inputted to the
ECM since the ignition
switch was turned on.

No fail-safe function.

B

ON

Brake Switch Malfunction

1. Throttle position is more

than 0%.

2. Engine speed is more than

693rpm (4JA1-TC) or
665rpm (4JH1-TC).

3. Vehicle speed is more than

0km/h.

4. Brake switch 1 signal and

brake switch 2 signal are
differently inputted to 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 P0703 (Symptom Code A) stored as
“Present Failure”?

—

Go to Step 3

Refer to

Diagnostic Aids

and Go to Step

3

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

6E–225

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 P0703 (Symptom Code A) stored in this
ignition cycle?

—

Go to Step 4

Refer to

Diagnostic Aids

and Go to Step

4

4

Check the “Stop Light fuse (10A)”.
If the fuse is burnt out, repair as necessary.
Was the problem found?

—

Verify repair

Go to Step 5

5

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

—

Verify repair

Go to Step 6

6

Using the DVM and check the brake switch 1.

1. Ignition “Off”, engine “Off”.

2. Remove the brake switch connector at the brake

pedal.

3. Check the brake switch 1.

Was the DVM indicated specified value?

Pedal is not

stepped on:

Continuity

Pedal stepped

on: No

continuity Go

to

Step 7

Replace pedal

switch and

verify repair

7

Using the DVM and check the brake switch 1 power
supply circuit.

1. Ignition “Off”, engine “Off”.

2. Remove the brake switch connector from the

brake switch.

3. Check the circuit for open circuit.

Was the DVM indicated specified value?

Battery
voltage

Go to Step 9

Go to Step 8

Step

Action

Value(s)

Yes

No

30

1

4

C-56

C-44

Brake Switch

1

4

V

1

C-44

6E–226

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

8

Repair the open circuit between the “Stop Light fuse
(10A)” and brake switch 1.
Is the action complete?

—

Verify repair

—

9

Using the DVM and check the brake switch 1 circuit.
Breaker box is available:

1. Ignition “Off”, engine “Off”.

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

connected) Ref. Page 6E-81

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 brake switch 1 and

check the circuit for open or short to voltage
circuit.

Was the problem found?

Pedal is not

stepped on:

Less than 1V

Pedal stepped

on: Battery

voltage Go

to

Step 12

Fixed at battery

voltage: Go to

Step 10

Fixed at less

than 1V: Go to

Step 11

10

Repair the short to voltage circuit between the brake
switch 1 connector and ECM.
Is the action complete?

—

Verify repair

—

11

Repair the open circuit between the brake switch 1
connector and ECM.
Is the action complete?

—

Verify repair

—

Step

Action

Value(s)

Yes

No

30

V

V

4

C-44

30

4

C-56

C-44

30

4

C-56

C-44