Navistar International DT 466 Diagnostic/Troubleshooting Manual page 487

7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
12–Pin Breakout Harness
Figure 475 IDM PWR circuit diagram
CAUTION: To avoid engine damage, turn the ignition switch to OFF before removing IDM relay or
disconnecting any connectors supplying power to the IDM. Failure to turn the ignition switch to OFF will
cause a voltage spike and damage to electrical components.
Voltage Checks at 12-pin Connector – Key-On Engine-Off (Check with breakout harness connected to
engine harness and chassis harness at 12–pin connector, IDM relay installed, and key-on engine-off. Follow
tests in order. Inspect for bent pins or corrosion.)
Test Point Spec
9 to gnd 12 V ±1.5 V Power from ignition switch to IDM. If no voltage, see truck Chassis Electrical
8 to gnd 0.06 V to 2
V
12 to gnd 12 V ±1.5 V IDM power from relay Pin 87. If no voltage, check from Pin 12 to Pin 87
6 to gnd 12 V ±1.5 V IDM logic power from relay Pin 87 with fuse. If fuse is blown, check for
1 to gnd 0 V to 0.25
V
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Comment
Circuit Diagram Manual for circuit numbers, connector and fuse locations.
IDM MPR – 12–pin connector. If > 2 V, check for open circuit between IDM
Pin X3–27 to Pin 8.
on relay for open or short to ground.
short to ground. If fuse is good, check for open circuit between fuse to Pin
6. See truck Chassis Electrical Circuit Diagram Manual for circuit numbers,
connector and fuse locations.
Ground – voltage reading indicates poor ground to battery. If voltage is
present check for open or high resistance between battery (–) and IDM pins.
EGES-270-1
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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