P0693

P0693 is the Fan 2 control circuit low version of the same fault family. On dual-fan applications fan 2 is the auxiliary or secondary fan, commanded on at higher ECT or with A/C high-side pressure above about 250 psi. Cheapest-first ladder: key-on engine-off, unplug the fan 2 relay or the fan 2 driver pin at the FCM and check the PCM control wire for a short to ground (should sit at battery voltage with no PCM command; 0 V at this measurement means the wire is grounded between PCM and relay). Measure relay coil resistance (50 to 90 ohms typical); a shorted coil reads under 10 ohms and confirms the relay is the cause. On scan-tool-commanded fan-on, expect 0 V on the control wire (low-side driver pulling to ground), current draw 3 to 25 A inrush settling to 4 to 15 A steady on a typical 12 to 14 inch electric fan, and less than 0.3 V drop across the fan power feed terminal under load. For PWM fan 2 outputs, duty cycle should ramp 0 to 100% smoothly as commanded; a clipped or stuck-high duty reading at the PCM monitor pin points to either the driver or the harness. Expensive-misdiagnosis caveat: fan resistor packs are the common consumable on multi-speed fan systems. Ford, GM, and Toyota all use 3-step fan resistor packs that burn open at the high-current stage; on dual-fan Toyota V6 platforms the resistor pack feeds both fans through staged relays, so a single failed pack will trip either P0691 or P0693 depending on which fan the PCM is currently commanding. Replace the pack, $40 to $120, before assuming the second fan motor failed.

Vehicle-specific patterns: 2011-2014 Ford F150 5.0 Coyote doesn't use a fan 2 on the single-PWM setup, so P0693 on this platform points to a misdiagnosis or to the FCM internal logic flagging a phantom output; verify scan-tool freeze-frame before chasing wiring. 2007-2014 GM Silverado/Tahoe/Yukon dual-system trucks throw P0693 from the electric secondary fan relay shorted to ground after coolant intrusion into the underhood fuse block (upper radiator hose drip is the classic source); $35 relay plus connector cleanup. 2007-2017 Toyota Camry V6 2GR-FE dual fan throws P0693 most commonly from the resistor pack high-stage open or from the fan 2 motor brushes worn out after 150k miles drawing under 1 A at command; pack first ($50 to $90), motor second ($180 to $320). 2006-2015 Honda Civic/Accord single-fan platforms don't have a fan 2 circuit; on Honda Pilot/Odyssey J35 V6 dual-fan setups P0693 is usually the auxiliary fan relay or chafed harness at the radiator support, $40 to $120. Estimated repair: $35 to $400.