Journey AWD V6-3.5L (2009)
Trailer Towing Relay: Description and Operation
Trailer Tow Relay - Operation
OPERATION
The trailer tow relays are electromechanical switches that use a low current input from the Totally Integrated Power Module (TIPM) to the tail lamps to
control a high current output to the trailer brake and turn signal lamps. Within each relay are an electromagnetic coil, a movable contact and two fixed
contact points. A resistor is connected in parallel with the coil, and helps to dissipate voltage spikes and electromagnetic interference that can be
generated as the field of the relay coil collapses.
The movable common supply contact point is held against the fixed normally closed contact point by spring pressure. When the relay coil is energized,
an electromagnetic field is produced by the coil windings. This field draws the movable contact away from the normally closed contact, and holds it
against the normally open contact. When the relay coil is de-energized, spring pressure returns the movable contact back against the normally closed
contact.
The inputs and outputs of the trailer tow relays include:
-
Common Supply Terminal (30) - The common feed terminal of both the left and right trailer tow stop/turn relays is connected to their respective
left or right trailer tow stop/turn signal pins of the 4-way trailer tow connector at all times. The common feed terminals of both the left and right
trailer tow stop relays is connected to the normally closed (87A) terminal of their respective left or right trailer tow stop/turn relay at all times.
-
Coil Ground Terminal (85) - The coil ground terminal of both the left and right trailer tow stop/turn relays is connected to their respective left or
right rear turn signal control circuits from the TIPM at all times. The coil ground terminals of both the left and right trailer tow stop relays are
connected to the stop lamp control circuit from the TIPM at all times.
-
Coil Battery Terminal (86) - The coil battery terminal of both the left and right trailer tow stop/turn relays is connected to a path to ground at all
times. The coil battery terminal of both the left and right trailer tow stop relays is connected to their respective left or right rear turn signal control
circuits from the TIPM at all times.
-
Normally Open Terminal (87) - The normally open terminal of both the left and right trailer tow stop/turn relays is connected to the stop lamp
control circuit from the TIPM whenever that relay is energized. The normally open terminal of both the left and right trailer tow stop relays is
connected to a path to ground whenever that relay is energized.
-
Normally Closed Terminal (87A) - The normally closed terminal of both the left and right trailer tow stop/turn relays is connected are connected
to the common supply (30) terminal of their respective left or right trailer tow stop relay whenever the relay is de-energized. The normally closed
terminal of both the left and right trailer tow stop relays is not connected to any circuit in this application.
The trailer tow relays and the hard wired circuits for the relays may be diagnosed using conventional diagnostic tools and procedures. Refer to the
appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the electronic controls and
communication between other modules and devices that provide some features of the trailer tow turn and stop lamp lighting system. The most reliable,
efficient, and accurate means to diagnose the electronic controls and communication related to trailer tow turn and stop lamp lighting operation requires
the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.
