power and grounding the vehicle. A three-wire connecting cable, 25 feet long and of adequate
line capacity to supply power for all heater units simultaneously, shall be furnished. Connecting
cable shall include a matching female connector at the vehicle end and a standard, three-pronged
(two power plus one ground) male connector at the other end. Electrical apparatus shall conform
to Federal Motor Carrier Safety Regulation 393.77(c)(7). Electrical insulation of the connecting
cable shall withstand normal operating stresses in low ambient air temperatures (down to minus
60 °F) without cracking or loss of dielectric capacity. All heater lead wires shall be installed
without interfering with vehicle component operation, and without loose excess wire. Provision
for storage of the cable shall be provided in the vehicle cab. Heaters shall be furnished as follows:
(a) Coolant heater, 1500-watt minimum rating, shall be installed in the engine block or in
the lower coolant inlet hose. An engine thermostat with an operating range of 170 °F
to 195 °F shall be installed;
(b) An oil pan heater of the permanent external surface mount, permanent in-pan mount,
or immersion type that meets the following requirements, shall be installed:
(1) Not less than 22 watts per quart heating capacity
(2) Not more than 18 watts per square inch heating capacity
(3) Thermal balance design or thermostat control providing for uninterrupted
(4) Provision for mounting below minimum service oil level.
(c) A fuel warmer or pre-heater shall be provided to prevent clogging of fuel filters due
to wax crystallization in the fuel. The fuel warmer shall use engine coolant to transfer
sufficient heat to the diesel fuel to heat it from an inlet temperature of minus 40°F to
an outlet temperature of plus 90 °F, with a flow rate not less than the maximum fuel
demand of the engine fuel system. A coolant shutoff valve shall be provided for the
coolant inlet inside of the fuel warmer unit.
3.4.2 Electrical system. The electrical system shall be in accordance with Federal Motor
Carrier Safety Regulations 393.27 through 393.31 and 393.33.
* 126.96.36.199 Starting system. A 12- or 24-volt starting system, with a 12-volt lighting system shall
be furnished. Engine starting equipment include an ether starting system or glow plug. If an ether
system is furnished in lieu of a glow plug, it shall be of the measured shot type. The measured
shot type ether system shall be key operated or manually operated from the driver's compartment
and shall be inoperative with the engine warm. Complete provisions for a replaceable ether
reservoir of not less than 12 fluid ounces shall be furnished. A reservoir need not be furnished.