Isuzu engine C22NE / 22LE / 20LE. Manual - part 99

DRIVEABILITY AND EMISSIONS  6E1-225

DIAGNOSTIC TROUBLE CODE DTC (Flash DTC=51)

ELECTRICALLY PROGRAMMABLE READ-ONLY MEMORY (EPROM) ERROR

Circuit Description

The Engine control module (ECM) used in this vehicle
utilizes an electrically programmable read- only
memory (EPROM). The EPROM contains program ID-
Calibration variable.
This malfunction checks the integrity of the EPROM
(ECM will not run), then DTC 51 will set.

Conditions for Setting the DTC

• If calculated check sum is not equal to the stored

check sum.

Action Taken When the DTC Sets

• The ECM will illuminate the malfunction indicator

lamp (MIL) the first time the malfunction is detected.

Conditions for Clearing the MIL/DTC

• Once the ECM determines that a fault(s) has been

rectified then the CEL will switch OFF, although the

fault code will remain in the ECM memory.

Any fault codes will remain in ECM memory until -

1. They are cleared by disconnecting the Battery

for more than 30 seconds.

2. A service tool such as Tech 2 is used to clear

them.

3. Ten consecutive starts without logging a fault.

Diagnostic Aids

• Diagnostic Trouble Code 51 indicates that the ECM

will not run. The only possible repair is the EPROM

or ECM replacement.

6E1-226  DRIVEABILITY AND EMISSIONS

DTC (Flash DTC = 51)

Electrically Programmable Read-Only Memory (EPROM) Error

Action

Value(s)

Yes

No

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

-

Go to step 2

Go to OBD

System

Check

Refer to Service Bulletins.
Is there still a problem?

-

Go to step 3

Verify Repair

Replace the EPROM or ECM.
Is the action complerte?

Note) Refer to 6E1-243.

Verify Repair

-

DRIVEABILITY AND EMISSIONS  6E1-227

DIAGNOSTIC TROUBLE CODE DTC (Flash DTC = 55)

ELECTRICALLY ERASABLE PROGRAMMABLE READ-ONLY MEMORY (EEPROM) ERROR

Circuit Description

The Engine control module (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, diagnostics operation.
This malfunction checks the integrity of
microprocessor config resister located in the
EEPROM (ECM will not run), then DTC 55 will set.

Conditions for Setting the DTC

• The ECM detects an internal program fault.

Action Taken When the DTC Sets

• The ECM will illuminate the malfunction indicator

lamp (MIL) the first time the malfunction is detected.

Conditions for Clearing the MIL/DTC

• Once the ECM determines that a fault(s) has been

rectified then the CEL will switch OFF, although the

fault code will remain in the ECM memory.

Any fault codes will remain in ECM memory until -

1. They are cleared by disconnecting the Battery

for more than 30 seconds.

2. A service tool such as Tech 2 is used to clear

them.

3. Ten consecutive starts without logging a fault.

Diagnostic Aids

• Diagnostic Trouble Code 55 indicates that ECM will

not run. The only possible repair is the EPROM or

ECM replacement.

6E1-228  DRIVEABILITY AND EMISSIONS

DTC (Flash DTC = 55)

Electrically Erasable Programmable Read-Only Memory Error

Action

Value(s)

Yes

No

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

-

Go to step 2

Go to OBD

System

Check

Refer to Service Bulletins.
Is there still a problem?

-

Go to step 3

Verify Repair

Replace the EPROM or ECM.
Is the action complerte?

Note) Refer to 6E1-243.

Verify Repair

-