PCI Bus Communication Failure - Body

PCI BUS COMMUNICATION FAILURE

PCI BUS Communication Failure:

POSSIBLE CAUSES
- (D25) PCI BUS circuit open at data link connector (DLC)
- (D25) PCI BUS circuit shorted to ground
- (D25) PCI BUS circuit shorted to voltage
- ANY PCI BUS module internally shorted to ground
- ANY PCI BUS module internally shorted to voltage

Diagnostic Test

1. ATTEMPT TO COMMUNICATION WITH ANY PCI BUS MODULE

NOTE:
- Determine which modules this vehicle is equipped with before beginning.
- When attempting to communicate with any PCI Bus module on this vehicle, the DRB can display 1 of 2 different communication errors: a NO RESPONSE message or a BUS +/- SIGNALS OPEN message.

Turn the ignition on.
Using the DRB, attempt to communicate with the Instrument Cluster (MIC).
Using the DRB, attempt to communicate with the Front Control Module (FCM).
Using the DRB, attempt to communicate with the Occupant Restraint Controller (ORC).

Q: Was the DRB able to communicate with one or more modules?

YES: Go To 2
NO: Go To 3

2. CHECK FOR A INTERMITTENT CONDITION
Turn the ignition off.

NOTE:
- Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or partially broken wires.
- Visually inspect the related wire harness connectors. Look for broken, bent, pushed out, or corroded terminals.
- If the DRB can NOT communicate with a single module.

Q: Were any problems found?

YES: Repair the wiring harness/connectors as necessary. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Test Complete.

3. (D25) PCI BUS CIRCUIT OPEN AT THE DLC
Turn the ignition off.
Disconnect the negative battery cable
Disconnect the DRB from the DLC.
Disconnect the PCM/ECM harness connectors. If equipped with NGC follow the caution below

CAUTION: 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.

Measure the resistance of the (D25) PCI Bus circuit between the DLC and the PCM/ECM harness connector.

Q: Is the resistance below 5.0 ohms?

YES: Go To 4
NO: Repair the (D25) PCI Bus circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

4. CHECK THE (D25) PCI BUS CIRCUIT FOR A SHORT TO VOLTAGE





NOTE: Reconnect the PCM/ECM harness connector and the negative battery cable.

Turn the ignition on.
Measure the voltage of the (D25) PCI Bus circuit at the DLC.

Q: Is the voltage steadily above 7.0 volts?

YES: Go To 5
NO: Go To 6

5. (D25) PCI BUS CIRCUIT SHORTED TO VOLTAGE




Turn the ignition off.
Using a voltmeter, connect one end to the (D25) PCI Bus circuit at the DLC and the other end to ground.

NOTE: When performing the next step, turn the ignition off and wait one minute before disconnecting any module. When the module is disconnected, turn the ignition on to check for a short to voltage.

Turn the ignition on.
While monitoring the voltmeter, disconnect each module the vehicle is equipped with one at a time.

Q: Is the voltage steadily above 7.0 volts with all the modules disconnected?

YES: Repair the (D25) PCI Bus circuit for a short to voltage. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Replace the module that when disconnected the short to voltage was eliminated. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

6. (D25) PCI BUS CIRCUIT SHORTED TO GROUND




Turn the ignition off.
Disconnect the negative battery cable.
Using a ohmmeter, connect one end to the (D25) PCI Bus circuit at the DLC and the other end to ground.
While monitoring the ohmmeter, disconnect each module the vehicle is equipped with one at a time.

NOTE: Total bus resistance to ground thru all of the modules is typically between 350 to 1000 ohms. The more modules on the PCI Bus, the lower the total resistance will be.

Q: Is the resistance below 150.0 ohms with all the modules disconnected?

YES: Repair the (D25) PCI Bus circuit for a short to ground. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Replace the module that when disconnected the short to ground was eliminated. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test