Dodge Ram 2004 Service Manual page 285

*NO RESPONSE FROM ECM (PCI BUS) - DIESEL ONLY —
TEST
2 With the DRBIII read ECM Diagnostic Trouble Codes. This is to ensure power and
grounds to the ECM are operational.
NOTE: If the DRBIII will not read ECM DTC's, follow the NO RESPONSE
TO ECM (SCI only) symptom path.
NOTE: If the vehicle will not start and the DRBIII displays a no response
message, refer to the appropriate symptom in the powertrain diagnostic
procedures.
Turn the ignition off.
Disconnect the ECM harness connectors.
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 DRBIII . Attach
the red and black leads and the cable to probe adapter to the scope input cable.
With the DRBIII 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 Probe to x10.
Press F2 again when complete.
Connect the Black lead to the ECM ground. Connect the Red lead to the PCI Bus
circuit in the ECM connector.
Turn the ignition on.
Observe the voltage display on the DRBIII Lab Scope.
Does the voltage pulse from 0 to approximately 7.5 volts?
Yes → Replace and program the Engine Control Module in accordance
No
ACTION
with the Service Information.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIE-
SEL).
→ Repair the PCI Bus circuit for an open.
Perform POWERTRAIN VERIFICATION TEST VER - 1 (DIE-
SEL).
271
COMMUNICATION
Continued
APPLICABILITY
All