Liberty Sport 2WD L4-2.4L VIN 1 (2002)
Parking Lamp Relay: Description and Operation
Fig.11 ISO Micro Relay
The park lamp relay is located in the Junction Block (JB) below the driver side outboard end of the instrument panel in the passenger compartment of
the vehicle. The park lamp relay is a conventional International Standards Organization (ISO) micro relay (Fig. 53). Relays conforming to the ISO
specifications have common physical dimensions, current capacities, terminal patterns, and terminal functions. The relay is contained within a small,
rectangular, molded plastic housing and is connected to all of the required inputs and outputs by five integral male spade-type terminals that extend from
the bottom of the relay base.
The park lamp relay cannot be adjusted or repaired and, if faulty or damaged, the unit must be replaced.
The park lamp relay is an electromechanical switch that uses a low current input from the Body Control Module (BCM) to control a high current output
to the park lamps. The movable common feed 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 electromagnetic field draws the movable relay contact point away from
the fixed normally closed contact point, and holds it against the fixed normally open contact point. When the relay coil is de-energized, spring pressure
returns the movable contact point back against the fixed normally closed contact point. A resistor is connected in parallel with the relay coil in the relay,
and helps to dissipate voltage spikes and electromagnetic interference that can be generated as the electromagnetic field of the relay coil collapses.
The park lamp relay terminals are connected to the vehicle electrical system through a connector receptacle in the Junction Block (JB). The inputs and
outputs of the headlamp low beam relay include:
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Common Feed Terminal - The common feed terminal (30) is connected to the park lamps through the park lamp relay output circuit and provides
ground to the park lamps when the relay is de-energized, and battery current to the park lamps whenever the relay is energized.
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Coil Ground Terminal - The coil ground terminal (85) is connected to a control output of the Body Control Module (BCM) through a park lamp
relay control circuit. The BCM controls park lamp operation by controlling a ground path through this circuit.
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Coil Battery Terminal - The coil battery terminal (86) receives battery current at all times from a fuse in the PDC through a fused B(+) circuit.
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Normally Open Terminal - The normally open terminal (87) receives battery current at all times from a fuse in the Power Distribution Center
(PDC) through a fused B(+) circuit.
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Normally Closed Terminal - The normally closed terminal (87A) is connected to ground at all times through a ground circuit that receives
ground through a splice block located in the instrument panel wire harness with an eyelet terminal connector that is secured by a nut to a ground
stud on the driver side instrument panel end bracket near the Junction Block (JB).
The park lamp relay can be diagnosed using conventional diagnostic tools and methods.
