Harness Resistance Checks; Operational Voltage Checks - Navistar International DT 466 Diagnostic/Troubleshooting Manual

292 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS

Harness Resistance Checks

Procedure
CAUTION: To avoid engine damage, turn the ignition
switch to OFF before disconnecting the connector or
relay for the ECM and IDM. Failure to turn the switch
to OFF will cause a voltage spike and damage to
electrical components.
1. Check harness resistance if high resistance or an
open circuit is suspected.
2. Connect breakout harness to harness only.
3. Connect breakout box to the ECM end of the
harness only.
4. Measure resistance from breakout box pin to the
breakout harness pin. Circuit wires should have a
resistance of less than 5 ohms.
See Circuit Diagnostics in this section for circuit
specifications.
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.

Operational Voltage Checks

Operational voltages checks determine In-range
faults or intermittent connections.
To determine
connections, monitor a suspected circuit and recreate
conditions likely to cause the problem.
Monitor signal voltage with the EST using continuous
monitor session and initiating KOEO Continuous
Monitor Test. See Circuit Diagnostics in this section
for circuit specifications.
Use a DMM and breakout harness or a DMM and
breakout box. See Circuit Diagnostics in this section
for circuit specifications.
EGES-270-1
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
in-range faults and intermittent