Use the correct trailer ball for your application.

Most couplers are stamped with the required trailer ball size.

Hitch
Positions for towing hitch receiverRadio and Navigation Assembly Communication Error
INSPECTION PROCEDURE
1 IDENTIFY THE COMPONENT SHOWN BY THE SUB-CODE
Enter the diagnostic mode.
Press the "LAN Mon" switch to change to "LAN Monitor"
mode.
Identify the component shown by the sub-code.
HINT:
"110 (multi-display)" i ...
Inspection
1. Inspect no. 3 Intake air control valve
assembly
(A) inspect actuator operation.
(1) With 26.7 Kpa (200 mm hg, 7.9 In. Hg) of
vacuum applied to the actuator, check that the
actuator rod moves.
(2) One minute after applying the vacuum, check
that the actuator rod does not return.
...
Active test
HINT:
Performing an ACTIVE TEST enables components
including the relays, VSV (Vacuum Switching Valve), and
actuators, to be operated without removing any parts.
The ACTIVE TEST can be performed with an intelligent
tester. Performing an ACTIVE TEST in the first step in
troubleshooting is one ...