Electrical Maintenance 8-20
AIR HEATER
The air heater heats the intake air to help the engine start in cold weather. The air heater is energised when the Preheat-Start switch
is held in the PREHEAT or START position, or when the microprocessor initiates a unit start-up (CYCLE-SENTRY switch in
the CYCLE position).
The air heater is mounted on the open end of the intake manifold. 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 0.1 to 0.2 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.
Hold the Preheat-Start switch in the PREHEAT position. The current draw should be approximately 89 amps at 12.5 volts. The
heater is probably defective if the current draw is less than 60 amps or more than 100 amps.
Air Heater – TK 482, TK 486 or TK 486V Engine
1. M6 Terminal
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