Chrysler Town, Dodge Caravan. Manual — part 784
Symptom:
*NO RESPONSE FROM ECM (SCI ONLY) - DIESEL ONLY
POSSIBLE CAUSES
CHECK ECM POWERS AND GROUNDS
CABIN HEATER ASSIST
SCI TRANSMIT CIRCUIT SHORTED TO VOLTAGE
SCI TRANSMIT CIRCUIT SHORTED TO GROUND
SCI TRANSMIT CIRCUIT OPEN
ENGINE CONTROL MODULE
TEST
ACTION
APPLICABILITY
1
Perform the symptom Checking ECM Power and Ground Circuits in the Driveability
category.
Did the vehicle pass this test?
All
Yes
→ Go To 2
No
→ Repair as necessary.
Perform ROAD TEST VERIFICATION - VER-2.
2
Turn the ignition off.
Disconnect the ECM harness connectors.
Disconnect the DRB from the DLC.
Measure the resistance between ground and the SCI Transmit circuit.
Is the resistance below 5.0 ohms?
All
Yes
→ Go To 3
No
→ Go To 4
3
Turn the ignition off.
Disconnect the Cabin Heater Assist C1 harness connector.
Measure the resistance between ground and the SCI Transmit circuit.
Is the resistance below 5.0 ohms?
All
Yes
→ Repair the SCI Transmit circuit for a short to ground.
Perform ROAD TEST VERIFICATION - VER-2.
No
→ Replace the Cabin Heater Assist in accordance with the service
information.
Perform ROAD TEST VERIFICATION - VER-2.
4
Turn the ignition off.
Disconnect the DRB from the DLC.
Disconnect the ECM harness connectors.
Disconnect the Cabin Heater Assist C1 harness connector.
Turn the ignition on.
Measure the voltage of the SCI Transmit circuit at the DLC connector (cav 7).
Is the voltage above 1.0 volt?
All
Yes
→ Repair the SCI Transmit circuit for a short to voltage.
Perform ROAD TEST VERIFICATION - VER-2.
No
→ Go To 5
372
COMMUNICATION
TEST
ACTION
APPLICABILITY
5
Turn the ignition off.
Disconnect the ECM harness connectors.
Disconnect the DRB from the DLC.
Measure the resistance of the SCI Transmit circuit between the ECM connector and
the DLC.
Is the resistance below 5.0 ohms?
All
Yes
→ Go To 6
No
→ Repair the SCI Transmit circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2.
6
If there are no possible causes remaining, view repair.
All
Repair
Replace and program the Engine Control Module in accordance
with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2.
373
COMMUNICATION
*NO RESPONSE FROM ECM (SCI ONLY) - DIESEL ONLY —
Continued
Symptom:
*NO RESPONSE FROM FRONT CONTROL MODULE
POSSIBLE CAUSES
ATTEMPT TO COMMUNICATE WITH ANOTHER MODULE
OPEN GROUND CIRCUIT(S)
OPEN PCI BUS CIRCUIT
FRONT CONTROL MODULE
TEST
ACTION
APPLICABILITY
1
Turn the ignition on.
With the DRB, attempt to communicate with the Airbag Control Module.
With the DRB, attempt to communicate with the Controller Antilock Brake (CAB)
module.
With the DRB, attempt to communicate with the Body Control Module (BCM).
Was the DRB able to I/D or communicate with any of the modules?
All
Yes
→ Go To 2
No
→ Refer to symptom list for problems related to the PCI Bus
Communication Failure.
Perform BODY VERIFICATION TEST - VER 1.
2
Turn the ignition off.
Remove the Front Control Module from the IPM.
Using a 12-volt test light connected to 12-volts, probe both Ground circuits.
Is the test light illuminated for each circuit?
All
Yes
→ Go To 3
No
→ Repair the Ground circuit(s) for an open.
Perform BODY VERIFICATION TEST - VER 1.
374
COMMUNICATION
TEST
ACTION
APPLICABILITY
3
Note: Ensure there is PCI Bus communication with other modules on the
vehicle before proceeding. If not, refer to the symptom list from the menu
and repair as necessary.
Remove the Front Control Module from the IPM.
Use Scope input cable CH7058, Cable to Probe adapter CH7062, and the red and
black test probes.
Connect the scope input cable to the channel one connector on the DRB. Attach the
red and black leads and the cable to probe adapter to the scope input cable.
With the DRBIII
t select Pep Module Tools.
Select lab scope.
Select Live Data.
Select 12 volt square wave.
Press F2 for Scope.
Press F2 and use the down arrow to set voltage range to 20 volts. Set the probe to x10.
Press F2 again when complete.
Connect the Black lead to the chassis ground. Connect the Red lead to the PCI Bus
circuit in the FCM connector.
Turn the ignition on.
Observe the voltage display on the DRB Lab Scope.
Does the voltage pulse from 0 to approximately 7.5 volts?
All
Yes
→ Go To 4
No
→ Repair the PCI Bus circuit for an open.
Perform BODY VERIFICATION TEST - VER 1.
4
If there are no possible causes remaining, view repair.
All
Repair
Replace the Front Control Module in accordance with the service
information.
Perform BODY VERIFICATION TEST - VER 1.
375
COMMUNICATION
*NO RESPONSE FROM FRONT CONTROL MODULE —
Continued
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