Regal V6-231 3.8L VIN L SFI (1990)
Chart C-12A Wiring Diagram
CIRCUIT DESCRIPTION:
The ECM and three relays are used to control the two cooling fans.
Low Speed Fan Operation - Low speed operation of both fans is controlled by the ECM. The ECM energizes the fan relay "B" (in the right hand power
center) for low speed fans when coolant temperature exceeds 101~C (214~F) or A/C requested. With ignition "OFF" the ECM will operate the cooling
fans at low speed if coolant temperature exceeds 110~C (230~F) and manifold air temperature exceeds 39~C (102~F) at time of key "OFF". The ECM
will keep the low speed fans "ON" with the key "OFF" for up to 2 minutes or until or until coolant temperature falls below 99~C (210~F).
High Speed Fan Operation - High speed fan operation of both fans is controlled by the ECM. The ECM energizes all three cooling fan relays when
coolant temperature exceeds 108~C (226~F) or A/C refrigerant pressure is sufficient to close the A/C head pressure switch (refrigerant pressure over
1380 kPa, 200 psi). High speed fans should not run with the ignition "OFF."
TEST DESCRIPTION:
Numbers below refer to circled numbers on the diagnostic chart.
1.
Code 14 or 15 could mean cooling system or sensor is not operating normally, and fan operation cannot be checked correctly.
2.
Selecting low speed fans under misc. test, fan control with Scanner causes the ECM to energize fan relay "B" and operates the fans at low speed.
3.
Selecting high speed fans under misc. test, fan control with Scanner causes the ECM to energize fan relays "B", "C", and "D" and operates the fans
at high speed.
4.
Cooling fans should run at low speed if an A/C mode is selected and the ECM is receiving an A/C request signal.
DIAGNOSTIC AIDS:
If fans operate normally but an overheat condition exist refer to Coolant Temperature to Resistance Values on Trouble Code Chart 15. Replace sensor if
Mis-Scaled. If not diagnose cooling system and radiator.
If coolant temperature exceeds 110~C (230~F) and manifold air temperature exceeds 39~C (102~F) at key "OFF," the ECM will keep the low speed fans
"ON" with the key "OFF" for up to two minutes or until coolant temperature falls below 99~C (210~F).
