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TK 56433-5-MM-EN
grounded 2 wire before replacing the fuse link. Replace
the fuse link by replacing the positive battery cable.
Air Heater
The air heater is mounted on the open end of the intake
manifold. It heats the intake air to help the engine start
in cold weather. The air heater is energized by the
microprocessor during preheat, just before the engine
is started.
The heater is probably defective if the resistance is
more than 0.2 ohms and the current draw is less than
60 amps, or if the current draw is more than 100 amps.
Check the resistance of the air intake heater with an
ohmmeter between the M6 terminal on the front of the
heater and the screw on the back of the heater (or the
heater case). The resistance should be 0.14 ± 0.02
ohms.
Check the current draw of the heater with a clamp-on
ammeter at the H1 wire near the M6 terminal on the
front of the heater. During preheat the current draw
should be approximately 70 amps.
Figure 11.
Air Heater
1.
M6 Terminal
Unit Wiring
Inspect the unit wiring and the wire harnesses during
scheduled maintenance inspections for loose, chafed,
or broken wires to protect against unit malfunctions
due to open or short circuits.
Wire Harness Routing
Do not change the factory routing of the wire harnesses
inside the unit.
