Test D

Pinpoint Test D: The Electric Cooling Fan(s) Is Inoperative In One Or More Speeds

Normal Operation
Under normal operation, in low speed, voltage is supplied to cooling fan relay 2 through circuit 1823 (YE/BK). When the relay is energized, voltage is fed to the RH cooling fan motor through circuit 1825 (LG/YE). The voltage is then fed from the RH cooling fan motor by circuit 461 (OG), through cooling fan relay 3 and to cooling fan relay 1 through circuits 3850 (LG/VT) and 1826 (YE/RD). From the cooling fan relay, voltage is fed to the LH cooling fan motor by circuit 1824 (LG/VT). Ground for the cooling fan motors is provided from the cooling fan resistor through circuit 471 (OG/LG), cooling fan relay 4 and circuit 462 (VT) to the LH cooling fan motor.

Under normal operation and in medium speed, voltage is supplied to cooling fan relay 2 through circuit 1823 (YE/BK) and to cooling fan relay 1 through circuit 1822 (LB). When the relays are energized, voltage is fed to the RH cooling fan motor through circuit 1825 (LG/YE) and to the LH cooling fan motor through circuit 1824 (LG/VT). Ground for the cooling fan motors is provided from the cooling fan resistor through circuit 471 (OG/LG) to cooling fan relay 4 (LH) and 5 (RH). The LH cooling fan motor ground is received from cooling fan relay 4 through circuit 462 (VT). The RH cooling fan motor ground is received from cooling fan relay 5 through circuit 3828 (OG/BK), cooling fan relay 3 (energized) and circuit 461 (OG).

Under normal operation and in high speed, voltage is supplied to cooling fan relay 2 through circuit 1823 (YE/BK) and to cooling fan relay 1 through circuit 1822 (LB). When the relays are energized, voltage is fed to the RH cooling fan motor through circuit 1825 (LG/YE) and to the LH cooling fan motor through circuit 1824 (LG/VT). Ground for the cooling fan motors is provided through circuit 1205 (BK) to cooling fan relay 4 (LH) and 5 (RH). The LH cooling fan motor ground is received from cooling fan relay 4 (energized) through circuit 462 (VT). The RH cooling fan motor ground is received from cooling fan relay 5 (energized) through circuit 3828 (OG/BK), cooling fan relay 3 (energized) and circuit 461 (OG).

Possible Causes
^ An open circuit 3850 (LG/VT), 1826 (YE/RD), 471 (OG/LG), 1205 (BK), 1823 (YE/BK), 1825 (LG/YE), 461 (OG), 3828 (OG/BK), 462 (VT), 1824 (LG/VT) or 1822 (LB).
^ A short to ground or short to voltage on circuit 3850 (LG/VT) or 1826 (YE/RD)
^ Cooling fan relay.
^ Cooling fan motor.
^ Cooling fan resistor.

Steps D1 - D2:

Steps D2 - D3:

Steps D4 - D6:

Steps D6 - D8:

Steps D8 - D10:

NOTE: Before carrying out the test, diagnose any PCM DTCs.