--- a/firmware/main/board_pins.h
+++ b/firmware/main/board_pins.h
@@ -22,8 +22,11 @@
 
 #define BOARD_PIN_I2C_SDA     14 /* 模组脚 22 —— 6×INA226 + 2×DAC + PCA9555（+ 载板 LM75） */
 #define BOARD_PIN_I2C_SCL     15 /* 模组脚 8 */
-#define BOARD_PIN_FAN_TACH    16 /* 模组脚 9  → R731/R732 分压 */
-#define BOARD_PIN_FAN_PWM     18 /* 模组脚 11 → R733 */
+/* KiCad FAN-R2: common power enable, inverted open-drain PWM, two receivers. */
+#define BOARD_PIN_FAN_EN       5 /* Module pin 5 -> R742/Q8; active high */
+#define BOARD_PIN_FAN_TACH_IN 16 /* Module pin 9 -> Q9; intake */
+#define BOARD_PIN_FAN_TACH_OUT 4 /* Module pin 4 -> Q10; exhaust */
+#define BOARD_PIN_FAN_PWM     18 /* Module pin 11 -> R733/Q6; GPIO duty = 1 - fan duty */
 #define BOARD_PIN_UP_VBUS_DET 47 /* 模组脚 24 → J24.25，上游 VBUS 有没有插 */
 #define BOARD_PIN_NTC1        1  /* 模组脚 39，ADC1_CH0 —— 必须是 IO1~IO10 */
 #define BOARD_PIN_NTC2        2  /* 模组脚 38，ADC1_CH1 */
--- a/firmware/main/rail_cfg.c
+++ b/firmware/main/rail_cfg.c
@@ -107,7 +107,7 @@
 static bool pins_ok(const rail_cfg_t *t)
 {
     /* 全板用掉的每一个脚。顺序无所谓，这里只查「都能用」和「不重复」。 */
-    int used[2 * PHONERAIL_RAIL_COUNT + 14];
+    int used[2 * PHONERAIL_RAIL_COUNT + 16];
     size_t n = 0;
 
     for (int rail = 1; rail <= PHONERAIL_RAIL_COUNT; rail++) {
@@ -116,7 +116,9 @@
     }
     used[n++] = BOARD_PIN_I2C_SDA;
     used[n++] = BOARD_PIN_I2C_SCL;
-    used[n++] = BOARD_PIN_FAN_TACH;
+    used[n++] = BOARD_PIN_FAN_EN;
+    used[n++] = BOARD_PIN_FAN_TACH_IN;
+    used[n++] = BOARD_PIN_FAN_TACH_OUT;
     used[n++] = BOARD_PIN_FAN_PWM;
     used[n++] = BOARD_PIN_UP_VBUS_DET;
     used[n++] = BOARD_PIN_NTC1;
--- a/firmware/test/test_rail_cfg.c
+++ b/firmware/test/test_rail_cfg.c
@@ -136,6 +136,20 @@
     TEST_ASSERT_EQUAL_HEX32(RAIL_SELFTEST_PINS, rail_selftest_table(t));
 }
 
+static void test_each_fan_pin_collision_is_caught(void)
+{
+    const int fan_pins[] = {
+        BOARD_PIN_FAN_EN, BOARD_PIN_FAN_PWM,
+        BOARD_PIN_FAN_TACH_IN, BOARD_PIN_FAN_TACH_OUT,
+    };
+    rail_cfg_t t[N];
+    for (unsigned i = 0; i < sizeof(fan_pins) / sizeof(fan_pins[0]); i++) {
+        copy_real_table(t);
+        t[0].efuse_en = fan_pins[i];
+        TEST_ASSERT_EQUAL_HEX32(RAIL_SELFTEST_PINS, rail_selftest_table(t));
+    }
+}
+
 /* 两样一起坏，两位一起报 —— 别在第一个错上就 return。 */
 static void test_two_kinds_of_breakage_report_two_bits(void)
 {
@@ -378,7 +392,8 @@
     static const int strapping[] = BOARD_PINS_STRAPPING;
     static const int reserved[] = BOARD_PINS_RESERVED;
     static const int others[] = {
-        BOARD_PIN_I2C_SDA, BOARD_PIN_I2C_SCL,  BOARD_PIN_FAN_TACH, BOARD_PIN_FAN_PWM,
+        BOARD_PIN_I2C_SDA, BOARD_PIN_I2C_SCL,  BOARD_PIN_FAN_TACH_IN, BOARD_PIN_FAN_PWM,
+        BOARD_PIN_FAN_EN, BOARD_PIN_FAN_TACH_OUT,
         BOARD_PIN_NTC1,    BOARD_PIN_NTC2,     BOARD_PIN_USB_DM,   BOARD_PIN_USB_DP,
         BOARD_PIN_UP_VBUS_DET, SR595_PIN_SER,  SR595_PIN_SRCLK,    SR595_PIN_RCLK,
         SR595_PIN_OE_N,    PCA9555_PIN_INT_N,
@@ -583,6 +598,7 @@
     RUN_TEST(test_a_faithful_copy_of_the_real_table_passes);
     RUN_TEST(test_a_cell_that_drifted_from_the_driver_is_caught);
     RUN_TEST(test_every_kind_of_bad_pin_is_caught);
+    RUN_TEST(test_each_fan_pin_collision_is_caught);
     RUN_TEST(test_two_kinds_of_breakage_report_two_bits);
     RUN_TEST(test_no_two_rails_share_anything);
     RUN_TEST(test_shift_chain_bits_avoid_hub_reset_and_the_unused_pins);