Dakota 4WD V8-4.7L VIN N (2000)
4. The coil battery terminal cavity (86) is connected to the ignition switch. When the ignition switch is placed in the ON position, fused ignition
switch output is directed from a fuse in the junction block to the relay electromagnetic coil to energize the relay. There should be battery voltage at
the PDC cavity for relay terminal 86 with the ignition switch in the ON position. If OK, go to Step 5. If not OK, repair the open circuit to the
junction block fuse as required.
5. The coil ground terminal cavity (85) is connected to ground. This terminal supplies the ground for the relay electromagnetic coil. There should be
continuity between the PDC cavity for relay terminal 85 and a good ground at all times. If not OK, repair the open circuit as required.
ADDITIONAL RELAY CIRCUIT TESTING
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The relay common feed terminal cavity 30 is connected to the low side of the blower motor. When the blower switch is Off and the ignition is On,
there should be battery voltage present on this circuit. When the ignition switch is On, the voltage at that point should vary based on blower switch
position.
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The normally closed contact cavity 87A is connected to the resistor block cavity 3. Check this circuit by turning the blower switch to High and
cycling between Heat and A/C modes. The voltage in the Heat mode should be approximately 2 volts. The blower switch must be in High blower
speed position during this check.
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The normally open contact on cavity 87 is tied to both the resistor block cavity 6 and the HVAC blower switch cavity 6. Check for continuity on
this circuit.
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The coil B+ contact cavity 86 is connected to an ignition run start feed. Battery voltage should be present on this circuit when the ignition switch is
in the Run position.
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The coil ground (-) cavity 85 is connected to the HVAC switch cavity 2 as well as the JTEC and A/C high pressure switch. Battery voltage should
be present on this circuit when the ignition switch is in the Run position and a Heat mode is selected on the control head. When an A/C mode is
selected, the voltage at this point should be less than 1 volt.
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If the blower motor does not operate, or only operates in some modes, check for a faulty connection at the VRR, or defective blower motor relay
(VRR).
