350 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
WARNING: To avoid serious personal injury, possible death, or damage to the engine or vehicle,
always disconnect main negative battery cable first. Always connect the main negative battery cable
last.
Voltage Check at Diagnostic Connector (Check at diagnostic connector
with key-on engine-off.)
Test Point
Spec Signal Comment
B to A B+ Power
Should be B+ power at B all times. If no power, check
ground and power circuits. See truck Chassis Electrical
Circuit Diagram Manual.
CtoA
1Vto4V Digital
signal
ThesumofCtoAandDtoAequals4Vto5V.
DtoA 1Vto4V Digital
signal
ThesumofCtoAandDtoAequals4Vto5V.
Resistance Check at Diagnostic Connector (Turn the ignition switch to OFF. Check at diagnostic
connector with negative battery cable disconnected.)
CtoA >1MΩ CAN+ If < 1 MΩ, a short between CAN+ and ground exists.
Disconnect ECM X3 and check again. If short is no longer
present, replace ECM. If short exists, harness or o ther node
component is inoperative.
DtoA
>1MΩ CAN – If < 1 M Ω, a short between CAN – and ground ex
ists.
Disconnect ECM X3 and check again. If sho
rt is no longer
present, replace ECM. If short still ex
ists, harness or oth er
node component inoperative.
CtoD 60Ω CAN The datalink has two terminating resistors in parallel of 120
Ω each. If > 70 Ω, check fo r missing terminating res ister
or open in the CAN+ or CAN – wires. If < 50 Ω,checkfor
extra terminating resistor. If < 5 Ω, check for short between
CAN+ and CAN –.
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
To Next Page
Loading...
Need help?
General