TM 5-2420-230-24-2
B3.9 and B5.9 Series Engines
Air Intake Manifold Heater (010-072)
Section 10 - Air Intake System - Group 10
Page 10-53
Normal Operation of the Intake Manifold Heater System
Temperature
Condition
Elements
Duration
Duty Cycle Percent ON/OFF
Below -19C
Preheat
Both
30 seconds
Continuous
[-2F]
Postheat
Both
15 seconds
Continuous
One
15 seconds
Continuous
One
40 seconds
50/50
One
106 seconds
25/75
-19 to -8C
Preheat
Both
20 seconds
Continuous
[-2 to 18F]
Postheat
Both
20 seconds
Continuous
One
20 seconds
Continuous
One
20 seconds
Continuous
One
40 seconds
50/50
One
106 seconds
25/75
-8 to 8C
Preheat
Both
10 seconds
Continuous
[18 to 46F]
Postheat
Both
10 seconds
Continuous
One
10 seconds
Continuous
One
10 seconds
Continuous
One
40 seconds
50/50
One
106 seconds
25/75
Below 8C
Preheat
None
[46F]
Postheat
None
Amperage Draw - 95 amps per element
To prevent excessive drain on the batteries, the electric heater controller has incorporated a battery monitoring
feature. If the battery VDC were dropped too low, the heater controller would delay the postheat cycle, prevent-
ing further drain on the batteries. This battery protection feature is only activated on vehicles with weak or
drained batteries.
*Heater control modules/electronic control modules with serial numbers below 0080000A will not have a preheat cycle
during this cycle.
L-1177
