K 20 P/U 4WD V8-454 7.4L (1985)
Radiator Cooling Fan Motor: All Technical Service Bulletins
Cooling - Engine Overheats, Electric Fan Reversed
Number:
85-206
Section:
6B
Date:
JUNE, 1986
Subject:
ENGINE OVERHEATS
Model and Year:
1985 C/K 20-30 WITH 7.4L (VIN CODE W) (454), H5D HEAVY DUTY EMISSIONS AND ELECTRIC BOOST COOLING
FAN
TO:
ALL CHEVROLET DEALERS
Some 1985 C/K 20-30 trucks equipped with the 454 engine, H5D heavy duty emissions, and the electric boost cooling fan may
experience an engine overheat at an extended idle or low vehicle speed operation (under 5 mph).
FAN HARNESS CONNECTOR WIRING REVERSAL
This condition may be caused by the electric boost cooling fan running in the reverse direction. If this condition is encountered, test
the fan to verify the airflow is toward the rear of the vehicle through the radiator. If the airflow from the fan is toward the front of the
vehicle, this condition can be corrected by reversing the wires in the fan harness connector. See Figure No. 1
This condition was corrected in production beginning with the following VIN breakpoints.
FLINT
105510
ST. LOUIS
110182
118383
JANESVILLE
116875
