LEMON Manuals: Even more car manuals for everyone
Home >> GMC >> 1993 >> Forward Control 6.2 J, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - System/Component Tests >> Miscellaneous ECM Controls >> Chart C-12A, Cooling Fan Circuit Diagnosis 3.8L >> Notes

Chart C-12A, Cooling Fan Circuit Diagnosis 3.8L: Notes

Power for fan motor goes through a 40-amp fusible link to terminal "A" of fan relays. Fan relays are energized when a good ground circuit is completed through Powertrain Control Module (PCM) quad-driver. PCM energizes puller relay through terminal "GC4", when coolant temperature reaches 212°F (100°C) or when A/C is requested. PCM energizes pusher relay if A/C refrigerant pressure reaches 210 psi (99°C) or coolant temperature reaches 226°F (108°C).

NOTE: Test numbers refer to numbers on diagnostic charts.
  1. Using Tech 1 miscellaneous tests, low speed fan control will cause PCM to ground circuit No. 335. Puller fan should operate.
  2. Using Tech 1 miscellaneous tests, high speed fan allows control of circuit No. 473. Pusher fan should operate.
  3. When jumpering coolant temperature sensor wires together, scan tester should display coolant temperature of 304°F (151°C). Both fans will operate when ignition is cycled from off to on.
  4. Opening A/C pressure switch will cause pusher fan to operate.
scientia non olet · About LEMON Manuals