Took my 03 Gr.Caravan 3.3 flex in for inspection, in NYstate.
The emission computer could not see the engine idling. Said that the wire connection was OK, just couldn't connect.
But, my Innova 3160d scanner was giving me the green light saying that all the monitors are well. Problem is that even my scanner kept loosing connection, off and on.
Checked the DLC wiring, both grounds measure OK, have a good 12 volts and the PCI and SCI leads to the PCM read good continuity.
Add to that, there is no MIL and the van runs fine.

Anybody been down this road? Any suggestions? I do not want to have to give an arm and a leg to a dealer to try to read the buses and then be told that a 500 dollar module needs replaced. AT 163k the van's not worth a huge investment.

Thanks for any help.

Stan

 

How about a slightly loose wire at the van's OBD connector? Have you tried wiggling the wires coming into that connector while your scanner is connected to see if anything happens by doing that?

 

Ditto. Wiggle everything in sight and watch the scanner for any loss of signal.

 

Take a look at the injector harness. And I believe the DLC should have 2.5 volts to 5.0 volts.

 

WIRING HARNESS INTERMITTENT
OPEN PCI BUS CIRCUIT AT THE DATA LINK CONNECTOR (DLC)
PCI BUS CIRCUIT SHORTED TO VOLTAGE
MODULE SHORT TO VOLTAGE
PCI BUS CIRCUIT SHORTED TO GROUND
MODULE SHORT TO GROUND
TEST ACTION APPLICABILITY
1 Note: Determine which modules this vehicle is equipped with before beginning.
Note: When attempting to communicate with any of the modules on this
vehicle, the DRB will 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 following control modules:
Airbag Control Module
Body Control Module
MIC (INSTRUMENT CLUSTER)
Was the DRBIIIt able to communicate with one or more Module(s)?
All
Yes ! Go To 2
No ! Go To 3
2 Turn the ignition off.
Note: Visually inspect the related wiring harness. Look for any chafed,
pierced, pinched, or partially broken wires.
Note: Visually inspect the related wire harness connectors. Look for broken,
bent, pushed out, or corroded terminals.
Note: If the DRB can not communicate with a single module, refer to the
category list for the related symptom.
Were any problems found?
All
Yes ! Repair wiring harness/connectors as necessary.
Perform BODY VERIFICATION TEST - VER 1.
No ! Test Complete.
33
COMMUNICATION
Turn the ignition off.
Disconnect the PCM/ECM harness connector. Note: 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.
Disconnect the DRB from the Data Link Connector (DLC).
Disconnect the negative battery cable.
Measure the resistance of the PCI Bus circuit between the Data Link Connector
(DLC) and the PCM/ECM harness connector.
Is the resistance below 5.0 ohms?
All
Yes ! Go To 4
No ! Repair the PCI Bus circuit for an open.
Perform BODY VERIFICATION TEST - VER 1.
4 NOTE: Reconnect the PCM/ECM harness connector and the negative battery
cable.
Turn the ignition on.
Measure the voltage of the PCI Bus circuit at the Data Link Connector (DLC).
Is the voltage above 7.0 volts?
All
Yes ! Go To 5
No ! Go To 6
5 Turn the ignition off.
Using a voltmeter, connect one end to the PCI Bus circuit at the DLC, and the other
end to ground.
Note: When performing the next step turn the ignition off (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.
Is the voltage steadily above 7.0 volts with all the modules disconnected?
All
Yes ! Repair the PCI Bus circuit for a short to voltage.
Perform BODY VERIFICATION TEST - VER 1.
No ! Replace the module that when disconnected the short to voltage
was eliminated.
Perform BODY VERIFICATION TEST - VER 1.
34
COMMUNICATIONTurn the ignition off.
Disconnect the negative battery cable.
Using a ohmmeter, connect one end to the 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 bus, the lower the total
bus resistance will be.
Is the resistance below 150.0 ohms with all the modules disconnected?
All
Yes ! Repair the PCI Bus circuit for a short to ground.
Perform BODY VERIFICATION TEST - VER 1.
No ! Replace the module that when disconnected the short to ground
was eliminated.
Perform BODY VERIFICATION TEST - VER 1.
35
COMMUNICATION

*PCI BUS COMMUNICATION FAILURE — Continued