P0696

P0696 is Fan 3 control circuit high - open or short-to-power on the high-speed/tertiary fan control wire. Cheapest-first ladder: key-on engine-off, measure the fan 3 control wire at the relay connector; it should sit at battery voltage uncommanded and drop to 0 V when the scan tool commands fan-on. If it stays at battery voltage when commanded, the PCM driver is open, the wire is broken, or the relay coil is open. Measure relay coil resistance (50 to 90 ohms typical); infinite reading confirms open coil. On 3-relay Ford Panther applications, the high-speed relay coil sees the most thermal cycling because it engages only at peak load (A/C max + ambient over 95 F + traffic), so its coil fails open earlier than the primary or secondary. With a scan tool commanding fan-on, current draw at the high-speed configuration should ramp 5 to 30 A momentary inrush to 8 to 20 A steady; less than 2 A measured at command points to a failed fan motor or open between relay and motor. PWM-monitored fan 3 outputs should show clean duty cycle 0 to 100% on the FCM input drive line. 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; the P0696 failure mode is most often the high-stage of the pack burned completely open such that no return path exists, which the PCM interprets as a circuit-high fault on the fan 3 output even though the wiring and relays test fine in isolation. Pull the pack, ohm each stage, replace if any stage reads infinite. Pack is $40 to $120; the whole fan module is $250 to $600.

Vehicle-specific patterns: 2003-2010 Ford Crown Victoria/Town Car/Marauder Panther-platform 3-relay setup throws P0696 from the high-speed relay coil open after about 100k miles of thermal cycling, $30 to $60 relay. 2007-2014 GM Silverado/Tahoe/Yukon trailer-tow third-fan setups throw P0696 from auxiliary fan motor open winding (brush failure) or from the auxiliary relay coil open, $35 to $400 depending on root cause. 2007-2017 Toyota Sequoia/Tundra 3UR-FE V8 with high-speed bypass relay plus 3-step resistor pack throws P0696 most commonly from the pack high-stage open ($50 to $90 pack) or less commonly from the bypass relay open coil ($40 to $80). 2008-2015 Honda Odyssey/Pilot J35 V6 dual-fan setups don't use a fan 3 output and P0696 on these platforms points to PCM calibration mismatch after a battery disconnect; reflash and retest. Estimated repair: $30 to $400.