10.14
ELECTRICAL
Accessory Power Test
PDM to Fan Output Test
Fan Motor Test
ACCESORY POWER Test
Test Procedure
The ignition switch must be turned to the "ON" position before completing this test. Measure DC volts
at the orange/white accessory terminal post leading from pin J on the PDM SSCB #1 connector.
Measurement should be at or near Battery voltage when RUN Signal
is present at PDM (Ignition Switch
in the "ON" position). RUN Signal
can be removed from the PDM by turning the Ignition Switch "OFF",
damaged wiring, or a faulty PDM.
What does passing
this test indicate?
Passing this test indicates the accessory lead, wire harness, connections, PDM, and RUN Signal are good.
What does failing
this test indicate?
Failing this test indicates there is a problem with the wire harness, connections, RUN Signal, battery, or
PDM. If Voltage is not present on the accessory lead, check wiring, connections, and battery before
proceeding to RUN Signal Test
.
PDM to FAN Output Test
Test Procedure
This test should be conducted with the vehicle Parking brake set and the Vehicle in Neutral with the engine
running. The PDM supplies power to the fan motor via pin K on SSCB # 1. To test the PDM for FAN
output, unplug the thermistor at the connector near the left side of the engine cylinder head. Measure the
DC voltage on the orange/black wire at the fan connector. Voltage should be at or near battery voltage.
What does passing
this test indicate?
A constant fan voltage of near battery voltage indicates that the fan output is correct.
What does failing
this test indicate?
Fan voltage less than battery voltage indicates a problem with the fan output circuit of the PDM. If the
fan output is 12 VDC for a few seconds then falls to zero, this means that the PDM is going into a safe
mode because the PDM has detected a no load condition. Proceed to Fan Motor Test
.
Fan Motor Test
Test Procedure
Disconnect the fan connector. Verify the fan is free to rotate before proceeding. Connect a DC ammeter
in-line with the orange/black wire. Ground the brown wire leaving the fan motor connector. Unplug the
thermistor at the left side of the engine cylinder head. With the vehicle parking brake set and the vehicle
in Neutral, start the engine. The cooling fan should start running. The ammeter should show a constant
current draw of 8.8 A or less.
What does passing
this test indicate?
A current measurement of 8.8 A or less indicates the fan motor is in good condition and is operating
properly.
What does failing
this test indicate?
A current draw of 0 A (the fan is not spinning) indicates that the fan motor is inoperative or it is not
receiving voltage from the PDM. If PDM to FAN Output Test
has already been passed, replace the fan
motor; if not, proceed to the PDM to FAN Output Test
after checking the fan for obstructions. Current
draw greater than 8.8 A indicates that the fan motor should be replaced, but only after checking the fan
for obstructions.
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