Navistar International DT 466 Diagnostic/Troubleshooting Manual page 453

7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
Harness Resistance Check – Element to Relay (Turn the ignition switch to OFF. Disconnect harness
from element terminal. Check for corrosion. Trace wiring harness from element to IAH relay. Ensure the
correct relay terminal is being tested.)
Element terminal 1 to relay
output terminal 1
Element terminal 2 to relay
output terminal 2
Voltage Check at Relays – Battery Feed Wires (Starter)
Relay 1: Battery feed terminal
to gnd
Relay 2: Battery feed terminal
to gnd
Voltage Check at Relays – Output (Output State Test) (Turn the ignition switch to ON. Run Glowplug /
Inlet Air Heater Output State Test. For help, see "Inlet Air Heater Output State Test" in Section 3 (page 68).)
Relay 1: Relay output post to
gnd
Relay 2: Relay output post to
gnd
Actuator Control Voltage Check at Relay Connection (Disconnect control wiring from relay. Turn the
ignition switch ON. Run the Glow Plug / Air Heater Output State Test. For help, see "Inlet Air Heater Output
State Test" in Section 3 (page 68).)
Element 1: A to gnd
Element 1: A to B
Element 2: A to gnd
Element 2: A to B
NOTE: If both relays are < B+, check wiring back to the ECM and 12-pin connector. Verify ECM programming.
The Glowplug / IAH parameter should be option 2 (IAH).
Actuator Control Voltage Check at ECM (Connect breakout box [X1 only] to ECM. Turn the ignition switch
to on. Run the Glow Plug / Inlet Air Heater Output State Test. For help, see "Inlet Air Heater Output State
Test" in Section 3 (page 68).)
Output State Test High
X1–17 to gnd
Output State Test Low
X1–17 to gnd
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
< 5 Ω If > 5 Ω, check for a corroded terminal or an open circuit.
< 5 Ω If > 5 Ω, check for a corroded terminal or an open circuit.
B+ If < B+, check for dead battery, open in IAH harness, or
open in truck battery harness.
B+ If < B+, check for dead battery, open in IAH harness, or
open in truck battery harness.
B+ If < B+, check for dead battery, open IAH harness, open
in truck battery harness, faulty IAH relay, ECM for IAH
programming, or open relay control circuit from ECM.
B+ If < B+, check for dead battery, open IAH harness, open
in truck battery harness, faulty IAH relay, ECM for IAH
programming, or open relay control circuit from ECM.
B+ If < B+, do Actuator Control Voltage Check at ECM (page
449).
B+ If < B+, do Harness Resistance Check – Relay to 12-pin
Connector. (page 450).
B+ If < B+, do Actuator Control Voltage Check at ECM (page
449).
B+
If < B+, do Harness Resistance Check – Relay to 12-pin
Connector. (page 450).
B+ If < B+, and ECM is programmed correctly, replace the
ECM.
0 V If > 0.25 V, and ECM is programmed correctly, replace the
ECM.
EGES-270-1
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
449