Isuzu 4JA1 Workshop Manual page 422

6E-168 Engine Control System (4JH1)
DTC P0703 (Symptom Code A, B) (Flash Code 25)
Circuit Description
The brake pedal switch is installed on the brake pedal
bracket. The brake pedal 1 switch is a normally open
type switch and the brake pedal 2 switch is a normally
closed type switch. When the brake pedal is pressed,
the brake pedal 1 switch signal is provided to the engine
control module (ECM) and the stoplights are turned ON.
Then, the brake pedal 2 switch signal to the ECM is
stopped (low voltage). If the ECM detects the brake
switch signals out of correlation, this DTC will set.
Condition for Running the DTC
• The ignition switch is ON.
• The engine speed is higher than 665 RPM.
• The vehicle speed is higher than 0 km/h (0 MPH).
Condition for Setting the DTC
• The ECM detects that the brake pedal 1 switch
(normally open type switch) signal and brake pedal
2 switch (normally closed type switch) signal
correlation error for longer than 30 seconds within
the enabling conditions ever since ignition switch is
ON. (Symptom Code A)
• The ECM detects that the brake pedal 1 switch
(normally open type switch) signal and brake pedal
2 switch (normally closed type switch) signal
correlation error for longer than 30 seconds.
(Symptom Code B)
Step
1 Did you perform the Diagnostic System Check-
Engine Controls?
2 1. Install the scan tool.
2. Turn ON the ignition, with the engine OFF.
3. Observe the Brake Pedal 1 Switch parameter
with the scan tool while fully depressing and
releasing the brake pedal.
Does the scan tool indicate Applied when the brake
pedal is applied and Released when the brake pedal
is released?
3 1. Check to ensure the brake pedal switch is
adjusted correctly. The plunger should be all the
way in when the pedal is released, yet should not
impede with the brake pedal full upward travel.
2. Adjust the brake pedal switch as necessary.
Did you find and correct the condition?
4 1. Turn OFF the ignition.
2. Inspect the Stop (15A) fuse (C-15) in the cabin
fuse block.
Is the Stop (15A) fuse (C-15) open?
Action
Action Taken When the DTC Sets
• The ECM illuminates the malfunction indicator
lamp (MIL) when the diagnostic runs and fails.
Condition for Clearing the MIL/DTC
• The ECM turns OFF the MIL when the diagnostic
runs and does not fail.
• A history DTC clears after 40 consecutive driving
cycles without a fault. Or clear with the scan tool.
Diagnostic Aids
• If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.
• Misadjusted brake pedal switch will cause this
DTC to set.
DTC P0703 (Symptom Code A, B) (Flash Code 25)
Schematic Reference: Engine Controls Schematics
Connector End View Reference: Engine Controls
Connector End Views or Engine Control Module (ECM)
Connector End Views
Value(s) Yes

Go to Step 2

Go to Step 10

Go to Step 22

Go to Step 5
No
Go to Diagnostic
System Check-
Engine Controls
Go to Step 3
Go to Step 4
Go to Step 6