Dodge Ram. Manual — part 65

Symptom List:

FCM - EEPROM CHECKSUM FAILURE
FCM - INTERNAL BOOTLOADER CHECKSUM FAILURE
FCM - INTERNAL FLASH MEMORY CHECKSUM FAILURE
FCM - PCI BUS INTERNAL - LOOPBACK FAILURE

Test Note:

All symptoms listed above are diagnosed using the same tests.

The title for the tests will be FCM - EEPROM CHECKSUM
FAILURE.

When Monitored and Set Condition:

FCM - EEPROM CHECKSUM FAILURE

When Monitored:

Set Condition:

When the EEPROM memory checksum is determined to be incorrect.

FCM - INTERNAL BOOTLOADER CHECKSUM FAILURE

When Monitored:

Set Condition:

When the bootloader checksum is determined to be incorrect.

FCM - INTERNAL FLASH MEMORY CHECKSUM FAILURE

When Monitored:

Set Condition:

When the flash memory checksum is determined to be incorrect.

FCM - PCI BUS INTERNAL - LOOPBACK FAILURE

When Monitored:

Set Condition:

When a loopback test has failed.

POSSIBLE CAUSES

INTERNAL FAILURE

TEST

ACTION

APPLICABILITY

1

Turn the ignition on.
With the DRB, erase FCM DTC’s.
Turn the ignition off then turn the ignition on and wait approximately 1 minute.
With the DRB, read FCM DTC’s.
Did this DTC reset?

All

Yes

→ Replace the Front Control Module in accordance with the service

information.
Perform BODY VERIFICATION TEST - VER 1.

No

→ Test Complete.

257

COMMUNICATION

Symptom:

FCM - MIC MESSAGES NOT RECEIVED

When Monitored and Set Condition:

FCM - MIC MESSAGES NOT RECEIVED

When Monitored:

With the ignition on.

Set Condition:

The FCM does not receive any messages from the MIC for at least 5

seconds.

POSSIBLE CAUSES

ATTEMPT TO COMMUNICATE WITH THE INSTRUMENT CLUSTER (MIC)

FRONT CONTROL MODULE

TEST

ACTION

APPLICABILITY

1

Turn the ignition on.
With the DRB, enter Body then Electro/Mech Cluster.
Was the DRB able to I/D or communicate with the Instrument Cluster (MIC)?

All

Yes

→ Go To 2

No

→ Refer to the Communication category for the related symptom.

Perform BODY VERIFICATION TEST - VER 1.

2

With the DRB, erase DTC’s.
Turn the ignition on and wait approximately 1 minute.
With the DRB, read DTC’s.
Did this DTC reset?

All

Yes

→ Replace the Front Control Module in accordance with the service

information.
Perform BODY VERIFICATION TEST - VER 1.

No

→ Test Complete.

258

COMMUNICATION

Symptom:

FCM - PCM MESSAGES NOT RECEIVED

When Monitored and Set Condition:

FCM - PCM MESSAGES NOT RECEIVED

When Monitored:

Withe the ignition on.

Set Condition:

The FCM does not receive any messages from the PCM for at least 5

seconds.

POSSIBLE CAUSES

PCM MESSAGES NOT RECEIVED

ATTEMPT TO COMMUNICATE WITH THE PCM

PCI BUS CIRCUIT OPEN

POWERTRAIN CONTROL MODULE

TEST

ACTION

APPLICABILITY

1

Turn the ignition on.
With the DRB, enter SYSTEM MONITORS then J1850 MODULE SCAN.
Is the PCM active on the BUS?

All

Yes

→ Erase DTC, if DTC resets replace the Front Control Module in

accordance with the service information.
Perform BODY VERIFICATION TEST - VER 1.

No

→ Go To 2

2

Turn the ignition on.
With the DRB, attempt to communicate with the PCM.
Was the DRB able to communicate with the PCM?

All

Yes

→ Go To 3

No

→ Refer to the communication category and perform the appropriate

symptom.
Perform BODY VERIFICATION TEST - VER 1.

259

COMMUNICATION

TEST

ACTION

APPLICABILITY

3

Turn the ignition off.
Disconnect the PCM harness connector.
CAUTION: IF NGC, DO NOT PROBE THE PCM HARNESS CONNECTORS.
PROBING THE PCM HARNESS CONNECTORS WILL DAMAGE THE PCM
TERMINALS RESULTING IN POOR TERMINAL TO PIN CONNECTION.
INSTALL MILLER SPECIAL TOOL #8815 TO PERFORM DIAGNOSIS.
Disconnect the DRBIII

t from the DLC.

Measure the resistance of the PCI Bus circuit between the PCM connector (from
special tool #8815 if NGC) and the DLC.
Is the resistance below 5.0 ohms?

All

Yes

→ Replace and program the Powertrain Control Module in accor-

dance with the service information.
Perform POWERTRAIN VERIFICATION TEST VER - 1.

No

→ Repair the PCI Bus circuit for an open.

Perform BODY VERIFICATION TEST - VER 1.

260

COMMUNICATION

FCM - PCM MESSAGES NOT RECEIVED —

Continued