Chart C-12, Cooling Fan Circuit Diagnosis (2 Of 2) 3.1L

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NOTE: Test numbers refer to test numbers on diagnostic charts.

Battery voltage should be available at cooling fan relay terminals "A" and "D" when ignition switch is in the ON position.
This checks ECM's ability to ground circuits No. 335 and 473. SERVICE ENGINE SOON light should be flashing at this point. If SERVICE ENGINE SOON light is not flashing, refer to G - TESTS W/ CODES article.
This test checks if cooling puller and pusher fan relays (circuits No. 533 and 702) are open. Jumpering relay terminals "A" and "E" by-passes relay, which should cause fans to operate, if motors and wiring are okay.

Fig 1: Cooling Fan Circuit Schematic (3.1L)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Cooling Fan Circuit Flow Chart, (3.1L) (2 Of 2)

Courtesy of GENERAL MOTORS CORP.