International VT 275 V6, Руководство пользователя

Страница: 33 / 112

ELECTRONIC CONTROL SYSTEM
33
International ® VT 275 V6 Engine
Inlet Air Heater Operation
• The VT 275 has an Inlet Air Heater
(IAH) element mounted in the front
of the intake manifold. The IAH is
used to improve cold start
operation, reduce emissions and
white smoke, and improve engine
warm-up. When the key is ON, the
ECM determines if the element
should be activated and for how
long, based on barometric pressure
and engine oil temperature. On time
is limited to prevent heater element
damage and to prevent damage to
the intake manifold.
The heater relay delivers full voltage
to the element if battery voltage is
normal, or the relay is pulsed by the
ECM to control the current if battery
voltage is above normal. If the
battery voltage is so low that the
starter motor operation may be
affected, the inlet air heater is disabled.
Relay Operation
• The IAH relay receives battery
power from the starter power feed
terminal. The normally open terminal
connects to the element through
the harness. One end of the relay
coil is always grounded through pin
4 of the engine 12-way connector.
The other end of the coil receives
12 volts from ECM pin X1-18 to
close the relay contacts.
Inlet Air Heater Diagnostics
• An additional wire on the normally
open terminal connects to ECM pin
X2-11. This diagnostic circuit
allows the ECM to determine if the
IAH relay is on when commanded
on by the ECM.
• The Inlet Air Heater can be turned
on using the KOEO Glow
Plug/Inlet Air Heater Test. The test
can only be activated twice per key
cycle. The ECM will delay the Inlet
Air Heater operation for three
seconds after the test is activated.
ECM
BATTERY
200 A
IAH
C
IAH
D
MAF / IAT
IAH
RELAY
EOT
STARTER IAH
BAP
X1-18 IAHC
X2-11 IAHD
N.O. TERMINAL
4
12-WAY
ENGINE TO CHASSIS
CONNECTOR
X1
X2
X3
X4
X1
X2
X3
X4