This task covers:
c. Operating Test
Trailer parked on level ground, brakes engaged
and wheels chocked.
Tool kit, mechanics general,
Release all pressure from the air system before you disconnect any components.
Pressurized air can cause serious personal injury.
Remove all power to trailer prior to making any repairs to the Electronic Control
Unit (ECU). Failure to do so may result in serious injury or death.
Release all air pressure from the air lines.
Identify and label all electrical cables and air lines connected to ECU.
Disconnect the air lines from the ECU and seal opening to lines with tape. Also seal ECU
air ports with tape or protective caps if available.
Disconnect electrical cables from the ECU sensor ports and seal ports with tape or
protective caps if available
Loosen and remove two mounting bolts and lock nuts securing ECU to bracket and remove
The ECU/dual modulator valve is supplied with black protective caps on
each sensor port. When a sensor cable is not plugged into a sensor port,
the black cap must remain on the connector port to protect it from dirt
Mount the ECU to the trailer bracket and orient the ECU so that the exhaust port faces
down. Secure using two 3/8 in. grade 8 bolts and new locknuts and torque the nuts to 18
lbs-ft (24 Nm). Plug all unused ports.
Clean threads to air lines and apply anti-seize tape to threads.
Connect air lines to ECU following label markers applied during removal.
Connect electrical sensor cables to ECU following label markers applied during removal
(Ref. electrical diagram).