Isuzu KB P190. Manual - part 452

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-191

DTC P0571 (Flash Code 26)

Circuit Description

The brake switch is installed on the brake pedal
bracket. The brake switch 1 is a normally open type
switch and the brake switch 2 is a normally closed type
switch. When the brake pedal is pressed, the brake
switch 1 signal is provided to the ECM and the
stoplights are turned ON. Then, the brake switch 2
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.

Condition for Setting the DTC

• The ECM detects a brake switch 1 (normally open

type switch) signal and brake switch 2 (normally
closed type switch) signal correlation error for
longer than 10 seconds over 33 times since
ignition switch is ON.

Action Taken When the DTC Sets

• The ECM will not illuminate the MIL or SVS lamp.

Refer to DTC Type Definitions for Action Taken
When the DTC Sets - Type D.

• The ECM inhibits cruise control.

Condition for Clearing the DTC

• Refer to DTC Type Definitions for Condition for

Clearing the DTC - Type D.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

• Misadjusted brake switch will cause this DTC to

set.

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Controls
Connector End Views or ECM Connector End Views

Circuit/ System Testing DTC P0571

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check -
Engine Controls?

—

Go to Step 2

Go to Diagnostic

System Check -
Engine Controls

Install a scan tool.

Turn ON the ignition, with the engine OFF.

Observe the Brake Switch 1 parameter with a
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?

—

Go to Step 8

Go to Step 3

Check to ensure the brake 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.

Adjust the brake switch as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 4

Turn OFF the ignition.

Disconnect the brake switch harness
connector.

Connect a test lamp between the battery
voltage feed circuit of the brake switch 1
harness (pin 1 of C-44) and a known good
ground.

Does the test lamp illuminate?

—

Go to Step 5

Go to Step 6

6E-192 ENGINE CONTROL SYSTEM (4JK1/4JJ1)

Turn ON the ignition, with the engine OFF.

Observe the Brake Switch 1 parameter with a
scan tool while momentarily jumping 3-amp
fused jumper wire across the brake switch
harness connector between pins 1 and 2 of
the C-44.

Does the scan tool indicate Applied when the circuit
is jumpered and Released when the circuit is not
jumpered?

—

Go to Step 14

Go to Step 7

Repair the open circuit or high resistance between
the Stop Light (15A) fuse and the brake switch (pin
1 of C-44). Check the Stop Light (15A) fuse first.

Did you complete the repair?

—

Go to Step 18

—

Test the signal circuit between the ECM (pin
21 of C-58) and the brake switch (pin 2 of C-
44) for the following conditions:

• An open circuit

• A short to battery or ignition voltage

• High resistance

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 15

Observe the Brake Switch 2 parameter with a 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?

—

Go to Diagnostic

Aids

Go to Step 9

Check to ensure the brake 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.

Adjust the brake switch as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 10

Turn OFF the ignition.

Disconnect the brake switch harness
connector.

Turn ON the ignition, with the engine OFF.

Connect a test lamp between the ignition
voltage feed circuit of the brake switch 2
harness (pin 4 of C-44) and a known good
ground.

Does the test lamp illuminate?

—

Go to Step 11

Go to Step 12

Observe the Brake Switch 2 parameter with a scan
tool while momentarily jumping 3-amp fused
jumper wire across the brake switch harness
connector between pins 3 and 4 of the C-44.

Does the scan tool indicate Released when the
circuit is jumpered and Applied when the circuit is
not jumpered?

—

Go to Step 14

Go to Step 13

Repair the open circuit or high resistance between
the Engine (10A) fuse and the brake switch (pin 4
of C-44). Check the Engine (10A) fuse first.

Did you complete the repair?

—

Go to Step 18

—

Step

Action

Value(s)

Yes

ENGINE CONTROL SYSTEM (4JK1/4JJ1) 6E-193

Test the signal circuit between the ECM (pin 1
of C-58) and the brake switch (pin 3 of C-44)
for the following conditions:

• An open circuit

• A short to battery or ignition voltage

• High resistance

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 15

Inspect for an intermittent and for poor
connections at the harness connector of the
brake switch (pins 1, 2, 3 and 4 of C-44).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 16

Turn OFF the ignition.

Disconnect the ECM harness connector.

Inspect for an intermittent and for poor
connections at the harness connector of the
ECM (pins 1 and 21 of C-58).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 18

Go to Step 17

Replace brake switch. Refer to Brake Switch
Replacement.

Did you complete the replacement?

—

Go to Step 18

—

Important: Replacement ECM must be
programmed and learned.
Replace the ECM. Refer to ECM Replacement.

Did you complete the replacement?

—

Go to Step 18

—

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

Clear the DTCs with a scan tool.

Turn OFF the ignition for 30 seconds.

Turn ON the ignition, with the engine OFF.

Observe the Brake Switch 1 and Brake Switch
2 parameter with a 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 on each parameter?

—

Go to Step 19

Go to Step 2

Observe the DTC Information with a scan tool.

Are there any DTCs that you have not diagnosed?

—

Go to DTC List

System OK

Step

Action

Value(s)

Yes

6E-194 ENGINE CONTROL SYSTEM (4JK1/4JJ1)

DTC P0601 (Flash Code 53)

Circuit Description

This diagnostic applies to internal microprocessor
integrity conditions within the ECM.

Condition for Setting the DTC

• The ECM detects that the calculated checksum

does not agree with the ECM internal registered
checksum.

Action Taken When the DTC Sets

• The ECM illuminates the SVS lamp when the

diagnostic runs and fails. Refer to DTC Type
Definitions for Action Taken When the DTC Sets -
Type C. (Euro 4 Specification)

• The ECM illuminates the MIL when the diagnostic

runs and fails. Refer to DTC Type Definitions for
Action Taken When the DTC Sets - Type A.
(Except Euro 4 Specification)

• The ECM limits fuel injection quantity.

• The ECM inhibits pilot injection.

• The ECM inhibits cruise control.

• The ECM stops engine running when the vehicle

speed is lower than 5 km/h (3 MPH) for 5 seconds.
The engine will run after the key is cycled when the
ignition has been tuned OFF for longer than 10
seconds.

Condition for Clearing the DTC

• Refer to DTC Type Definitions for Condition for

Clearing the SVS Lamp/ DTC - Type C. (Euro 4
Specification)

• Refer to DTC Type Definitions for Condition for

Clearing the MIL/ DTC - Type A. (Except Euro 4
Specification)

Circuit/ System Testing DTC P0601

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check -
Engine Controls?

—

Go to Step 2

Go to Diagnostic

System Check -
Engine Controls

Install a scan tool.

Turn OFF the ignition for 30 seconds.

Turn ON the ignition, with the engine OFF.

Monitor the DTC Information with a scan tool.

Does the DTC fail this ignition?

—

Go to Step 3

Go to Step 4

Important: Replacement ECM must be
programmed and learned.
Replace the ECM. Refer to ECM Replacement.

Did you complete the replacement?

—

Go to Step 4

—

Clear the DTCs with a scan tool.

Turn OFF the ignition for 30 seconds.

Start the engine.

Operate the vehicle within the Conditions for
Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/ Failure
Records.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 5

Observe the DTC Information with a scan tool.

Are there any DTCs that you have not diagnosed?

—

Go to DTC List

System OK

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