PCM Messages Not Received (FCM)

PCM MESSAGES NOT RECEIVED (FCM)

WHEN MONITORED
With the ignition on.

SET CONDITION
The FCM does not receive any messages from the PCM for atleast 5 seconds.

POSSIBLE CAUSES
- (D25) PCI BUS circuit open
- Powertrain control module power and ground
- Front control module

Diagnostic Test

1. CHECK THE STATUS OF THE PCM ON THE PCI BUS NETWORK
Turn the ignition on.
With the DRB, enter System Monitors then J1850 Module Scan.

Q: Is the PCM active on the bus?

YES: Erase the DTC, if the DTC resets replace the Front Control Module. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 2

2. ATTEMPT TO COMMUNICATE WITH THE PCM
With the DRB, attempt to communicate with the PCM.

Q: Was the DRB able to communicate with the PCM?

YES: Go To 3
NO: Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

3. CHECK THE (D25) PCI BUS CIRCUIT FOR AN OPEN




Turn the ignition off.
Disconnect the PCM harness connector.

CAUTION: If the vehicle is equipped with an NGC controller, 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 DRB from the DLC.
Measure the resistance of the PCI Bus circuit between the PCM connector (from special tool #8815 if NGC) and the DLC.

Q: Is the resistance below 5.0 ohms?

YES: Replace and program the PCM. Perform the appropriate VERIFICATION TEST.
NO: Repair the PCI Bus circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test