Full Size Buick FWD V6-181 3.0L (1984)
Fig. 022 - Wiring Diagram for Chart C-12A-2 Coolant Fan No Low Speed Check. VIN E
CHART C-12A-2 COOLANT FAN - NO LOW SPEED CHECK
1.
Checks for normal low speed operation if relay is grounded. If fan comes "on" by grounding relay, fault is an open to ground through switch
circuit.
2.
Checks for ground in circuit to ECM that normally keeps low speed fan "off" when TCC is engaged. When ECM signals TCC engagement,
Terminal "P" on the ECM is switched to ground. The same circuit also goes to the low speed relay, which turns "off" low speed fan. If the ECM
circuit to "P" was grounded all the time, no low speed fan will occur. Test light will be "off" in a normal (not grounded) circuit.
3.
By jumping the relay connector in this step, the contact points in the relay are bypassed. If the fan comes "on," fault is in relay wiring or relay. No
fan operation indicates faulty fan wiring or fan motor.
