Disable is now multi extruder compatible. M84 got a T option.

Marlin/Configuration.h

 // 301 = Rambo
 
 #ifndef MOTHERBOARD
-#define MOTHERBOARD 7
+#define MOTHERBOARD 34
 #endif
 
 

Marlin/Configuration_adv.h

 //===========================================================================
 
 // This defines the number of extruders
-#define EXTRUDERS 1
+#define EXTRUDERS 2
 
 #define ENDSTOPS_ONLY_FOR_HOMING // If defined the endstops will only be used for homing
 

Marlin/Marlin_main.cpp

           if(code_seen('Z')) disable_z();
           #if ((E0_ENABLE_PIN != X_ENABLE_PIN) && (E1_ENABLE_PIN != Y_ENABLE_PIN)) // Only enable on boards that have seperate ENABLE_PINS
             if(code_seen('E')) {
-              disable_e0();
-              disable_e1();
-              disable_e2();
-            }
+              if(code_seen('T')) {
+                tmp_extruder = code_value();
+                if(tmp_extruder >= EXTRUDERS) {
+                  SERIAL_ECHO_START;
+                  SERIAL_ECHOLN(MSG_INVALID_EXTRUDER);
+                }
+                else {
+                  if(tmp_extruder == 0) disable_e0();
+                  else if(tmp_extruder == 1) disable_e1();
+                  else if(tmp_extruder == 2) disable_e2();
+               }
+             }
+             else {
+               disable_e0();
+               disable_e1();
+               disable_e2();
+             }
+          }
           #endif 
         }
       }

Marlin/planner.cpp

   unsigned char x_active = 0;
   unsigned char y_active = 0;  
   unsigned char z_active = 0;
-  unsigned char e_active = 0;
+  unsigned char e0_active = 0;
+  unsigned char e1_active = 0;
+  unsigned char e2_active = 0;
   unsigned char fan_speed = 0;
   unsigned char tail_fan_speed = 0;
   block_t *block;
       if(block->steps_x != 0) x_active++;
       if(block->steps_y != 0) y_active++;
       if(block->steps_z != 0) z_active++;
-      if(block->steps_e != 0) e_active++;
+      if(block->steps_e != 0) {
+         if(block->active_extruder == 0) e0_active++;
+         if(block->active_extruder == 1) e1_active++;
+         if(block->active_extruder == 2) e2_active++;
+      }
       if(block->fan_speed != 0) fan_speed++;
       block_index = (block_index+1) & (BLOCK_BUFFER_SIZE - 1);
     }
   if((DISABLE_X) && (x_active == 0)) disable_x();
   if((DISABLE_Y) && (y_active == 0)) disable_y();
   if((DISABLE_Z) && (z_active == 0)) disable_z();
-  if((DISABLE_E) && (e_active == 0))
-  {
-    disable_e0();
-    disable_e1();
-    disable_e2(); 
+  if(DISABLE_E) {
+    if(e0_active == 0) disable_e0();
+    if(e1_active == 0) disable_e1();
+    if(e2_active == 0) disable_e2();
   }
 #if FAN_PIN > -1
   #ifndef FAN_SOFT_PWM
   // Enable all
   if(block->steps_e != 0)
   {
-    enable_e0();
-    enable_e1();
-    enable_e2(); 
+    if(extruder == 0) enable_e0();
+    if(extruder == 1) enable_e1();
+    if(extruder == 2) enable_e2(); 
   }
 
   if (block->steps_e == 0)