vehicle of adequate capacity. Attach the hooks of the
safety chains (25) to the tow vehicle.
o. Attach the auxiliary service cable on the aft end of
the tow vehicle to the connector assembly (64, figure 7-
27) to provide 12-volt electrical power for the auxiliary
trailer light system.
p. Remove the dummy couplers with vent (23, figure
7-28) from the brake system fittings, if installed.
Connect the tow vehicle air brake system supply hoses
to the couplers (21).
q. Release the hand brake levers on the test trailer
and auxiliary trailer prior to towing.
Failure to observe the towing speed
limitations specified in the following
step may result in damage to the
r. Tow the test trailer and auxiliary trailer at a speed
not to exceed 20 mph on paved, smooth highways. Tow
each trailer over unimproved roads at 8 mph maximum