Navistar International DT 466 Diagnostic/Troubleshooting Manual page 389

7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
85 to gnd 0.06 V to 2 V
87 to gnd 12 V ±1.5 V
CAUTION: To avoid engine damage, turn the ignition switch to OFF before removing main power relay or any
ECM connector supplying power to the ECM. Failure to turn the ignition switch to OFF will cause a voltage
spike and damage to electrical components.
Voltage Checks at ECM – Key-On Engine-Off (Follow tests in order. Check with breakout box connected
between chassis harness and ECM. Inspect for bent pins and corrosion.)
Test Point Spec
X3–3 to gnd 12 V ±1.5 V
X3–6 to gnd 0 V to 0.25 V
X3–7 to gnd 0 V to 0.25 V
X3–5 to gnd 0.06 V to 2 V
X4–1 to gnd 12 V ±1.5 V
X4–2 to gnd 12 V ±1.5 V
CAUTION: To avoid engine damage, turn the ignition switch to OFF before removing main power relay or any
ECM connector supplying power to the ECM. Failure to turn the ignition switch to OFF will cause a voltage
spike and damage to electrical components.
Harness Resistance Checks – ECM to Main Power Relay (Turn the ignition switch to OFF. Inspect for bent
pins or corrosion. Connect relay breakout harness and breakout box to X3 and X4 chassis harness only.)
Test Point
X3–5 to 85 (ECM relay)
X4–1 to 87 (ECM relay)
X4–2 to 87 (ECM relay)
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
If > 2 V is present, check for open circuit between Pin X3–5 to Pin 85 on
relay or V circuit. See truck Chassis Electrical Circuit Diagram Manual
IGN
for relay and fuse locations.
Continuous voltage. If previous test points are in spec and no voltage is
present, replace relay.
Comment
Power from ignition switch to ECM. If no voltage, see truck Chassis
Electrical Circuit Diagram Manual for relay and fuse locations.
Ground – voltage reading indicates poor ground to battery. If voltage
is present check for open or high resistance between battery (–) and
ECM pins.
Ground – voltage reading indicates poor ground to battery. If voltage
is present check for open or high resistance between battery (–) and
ECM pins.
ECM grounds relay through internal transistor. If > 2 V is present, replace
ECM.
Power from relay to ECM. If no voltage, check for open between X4–1
and 87 on ECM relay. See truck Chassis Electrical Circuit Diagram
Manual for relay and fuse locations.
Power from relay to ECM. If no voltage, check for open between X4–2
and 87 on ECM relay. See truck Chassis Electrical Circuit Diagram
Manual for relay and fuse locations.
Spec Comment
< 5 Ω If > 5 Ω, check connections for open between ECM and relay.
See truck Chassis Electrical Circuit Diagram Manual for relay and
fuse locations.
< 5 Ω If > 5 Ω, check connections for open between ECM and relay.
See truck Chassis Electrical Circuit Diagram Manual for relay and
fuse locations.
< 5 Ω If > 5 Ω, check connections for open between ECM and relay.
See truck Chassis Electrical Circuit Diagram Manual for relay and
fuse locations.
EGES-270-1
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
385