7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS 291
voltage that the control side was switching, either
power or ground.
If the ECM is switching the ground circuit, the
other s ide of the actuator circuit should measure
more than 1 k ohms from the connector pin to
connector 9260 Pin A.
If the ECM is sw itch ing the power circuit, the other
side of the actuator circuit should measure less
than 5 ohms from the connector pin to connector
9260 Pin A.
Connector Resistance Checks to Chassis Ground
Figure 372 Resistance check to chassis ground
Procedure
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.
NOTE: The truck Chassis Electrical C ircuit Diagram
Manual should always be used for chassis ground
circuit information.
1. Disconnect chassis connector 9260.
NOTE: Connector 9260 is a 2-wire connector
usually located in the battery box. Pin A is the
chassis ground connection for the ECM and IDM.
See truck Chassis Electrical Circuit Dia gram
Manual for complete chassis side ECM and IDM
ground circuit information.
2. Connect breakout harness to harness only.
3. Disconnect negative battery cable.
4. Use breakou t harness to me asure resistance fro m
the lead of the breakout harness to the negative
battery cable.
See Circuit D iag n os tics in this section for circu it
specifications.
Sensor signal ground circuits should measure
greater than 5 00 ohms.
V
REF
and signal circuits should measure more than
1kohm.
The control side of an actuator will measure more
than 1 k ohms, but the expected voltage for the
other side of the actuator circuit will measure the
voltage that the control side was switching, either
power or ground.
If the ECM is switching the ground circuit, the
other side of the actuator circuit should measure
more than 1 k ohms from the connector pin to
battery ground.
If the ECM is switching the power circuit, the other
side of the actuator circuit should measure greater
than 500 ohms from the connector pin to battery
ground.
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.
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