Index: firmware/App/Services/SystemComm.c
===================================================================
diff -u -r754057a5f3b2412271b23bfffef39ada8fab7bcb -r97a93f387f6797fc747895fc915323220db12573
--- firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision 754057a5f3b2412271b23bfffef39ada8fab7bcb)
+++ firmware/App/Services/SystemComm.c	(.../SystemComm.c)	(revision 97a93f387f6797fc747895fc915323220db12573)
@@ -60,6 +60,8 @@
 #define MAX_FPGA_CLOCK_SPEED_ERRORS     3       ///< maximum number of FPGA clock speed errors within window period before alarm
 #define MAX_FPGA_CLOCK_SPEED_ERROR_WINDOW_MS    (10 * SEC_PER_MIN * MS_PER_SECOND)    ///< FPGA clock speed error window
 
+#define PENDING_ACK_LIST_OVERRIDE_UI_CHANNEL    1                                     ///< Value for determining UI or DG channel when Pending ACKs are overriden.
+
 #pragma pack(push, 1)
 
 /// Record for transmitted message that is pending acknowledgment from receiver.
@@ -112,7 +114,8 @@
 static U32 timeOfLastDGCheckIn = 0;                                         ///< Last time DG checked in
 static volatile BOOL uiIsCommunicating = FALSE;                             ///< Has UI sent a message since last check
 static U32 timeOfLastUICheckIn = 0;                                         ///< Last time UI checked in
-static volatile BOOL uiDidCommunicate = FALSE;                              ///< Has UI every sent a message
+static volatile BOOL uiDidCommunicate = FALSE;                              ///< Has UI every sent a message
+static OVERRIDE_U32_T pendingACKOverride = { 0, 0, 0, 0 };                  ///< Pending ACK override data structure.
 
 // ********** private function prototypes **********
 
@@ -907,7 +910,8 @@
     // Find expired messages pending ACK
     for ( i = 0; i < PENDING_ACK_LIST_SIZE; i++ )
     {   // Pending ACK expired?
-        if ( ( TRUE == pendingAckList[ i ].used ) && ( TRUE == didTimeout( pendingAckList[ i ].timeStamp, MSG_NOT_ACKED_TIMEOUT_MS ) ) )
+        if ( ( ( TRUE == pendingAckList[ i ].used ) && ( TRUE == didTimeout( pendingAckList[ i ].timeStamp, MSG_NOT_ACKED_TIMEOUT_MS ) ) ) ||
+             ( getU32OverrideValue( &pendingACKOverride ) > 0 ) )
         {   // If retries left, reset and resend pending message
             if ( pendingAckList[ i ].retries > 0 )
             {   // Re-queue message for transmit
@@ -921,10 +925,13 @@
                 U16 msgID;
 
                 memcpy( &msgID, (U08*)&pendingAckList[ i ].msg[ sizeof( U08 ) + sizeof( U16) ], sizeof( U16 ) );
-                if ( pendingAckList[ i ].channel != COMM_BUFFER_OUT_CAN_HD_2_DG )
+
+                if ( ( pendingAckList[ i ].channel != COMM_BUFFER_OUT_CAN_HD_2_DG ) ||
+                     ( getU32OverrideValue( &pendingACKOverride ) == PENDING_ACK_LIST_OVERRIDE_UI_CHANNEL ) )
                 {
                     SET_ALARM_WITH_1_U32_DATA( ALARM_ID_HD_CAN_MESSAGE_NOT_ACKED_BY_UI, (U32)msgID );
                 }
+
                 else
                 {
                     SET_ALARM_WITH_1_U32_DATA( ALARM_ID_HD_CAN_MESSAGE_NOT_ACKED_BY_DG, (U32)msgID );
@@ -1798,6 +1805,10 @@
                 handleTestHDRAMStatusOverrideRequest( message );
                 break;
 
+            case MSG_ID_HD_CAN_RECEIVE_ACK_MESSAGE_OVERRIDE:
+                handleTestHDPendingACKOverrideRequest( message );
+                break;
+
             // The default cannot be reached in VectorCAST since the cases are run in a for loop
             default:
                 // Unrecognized message ID received - ignore
@@ -1806,4 +1817,54 @@
     }
 }
 
+
+/*************************************************************************
+ *                       TEST SUPPORT FUNCTIONS
+ *************************************************************************/
+
+
+/*********************************************************************//**
+ * @brief
+ * The testSetPendingACKOverride function overrides the
+ * pendingACKOverride variable.
+ * @details Inputs: none
+ * @details Outputs: pendingACKOverride
+ * @param value override for pendingACKOverride
+ * @return TRUE if override successful, FALSE if not
+ *************************************************************************/
+BOOL testSetPendingACKOverride( U32 value )
+{
+    BOOL result = FALSE;
+
+    if ( TRUE == isTestingActivated() )
+    {
+        result = TRUE;
+        pendingACKOverride.ovData = value;
+        pendingACKOverride.override = OVERRIDE_KEY;
+    }
+
+    return result;
+}
+
+/*********************************************************************//**
+ * @brief
+ * The testResetPendingACKOverride function resets the override
+ * of the pendingACKOverride variable.
+ * @details Inputs: none
+ * @details Outputs: pendingACKOverride
+ * @return TRUE if override reset successful, FALSE if not
+ *************************************************************************/
+BOOL testResetPendingACKOverride( void )
+{
+    BOOL result = FALSE;
+
+    if ( TRUE == isTestingActivated() )
+    {
+        result = TRUE;
+        pendingACKOverride.override = OVERRIDE_RESET;
+        pendingACKOverride.ovData = pendingACKOverride.ovInitData;
+    }
+
+    return result;
+}
 /**@}*/
Index: firmware/App/Services/SystemComm.h
===================================================================
diff -u -r0a4dcd288d4347b85baaa0b07da568b6add5eac7 -r97a93f387f6797fc747895fc915323220db12573
--- firmware/App/Services/SystemComm.h	(.../SystemComm.h)	(revision 0a4dcd288d4347b85baaa0b07da568b6add5eac7)
+++ firmware/App/Services/SystemComm.h	(.../SystemComm.h)	(revision 97a93f387f6797fc747895fc915323220db12573)
@@ -57,7 +57,9 @@
 BOOL isUICommunicating( void );
 BOOL uiCommunicated( void );
 BOOL isHDOnlyCANNode( void );
-BOOL addMsgToPendingACKList( MESSAGE_T *msg, COMM_BUFFER_T channel, U08 *msgData, U32 len );
+BOOL addMsgToPendingACKList( MESSAGE_T *msg, COMM_BUFFER_T channel, U08 *msgData, U32 len );
+BOOL testSetPendingACKOverride( U32 value );
+BOOL testResetPendingACKOverride( void );
 
 /**@}*/
 
Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -r0826b00090b65c16a3e52e006cc3c016a6bf6a08 -r97a93f387f6797fc747895fc915323220db12573
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 0826b00090b65c16a3e52e006cc3c016a6bf6a08)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 97a93f387f6797fc747895fc915323220db12573)
@@ -8431,4 +8431,36 @@
     sendTestAckResponseMsg( (MSG_ID_T)message->hdr.msgID, result );
 }
 
+/*********************************************************************//**
+ * @brief
+ * The handleTestHDPendingACKOverrideRequest function handles a
+ * request to override pending ACKs.
+ * @details Inputs: none
+ * @details Outputs: message handled
+ * @param message : a pointer to the message to handle
+ * @return none
+ *************************************************************************/
+void handleTestHDPendingACKOverrideRequest( MESSAGE_T *message )
+{
+    TEST_OVERRIDE_PAYLOAD_T payload;
+    BOOL result = FALSE;
+
+    // Verify payload length
+    if ( sizeof( TEST_OVERRIDE_PAYLOAD_T ) == message->hdr.payloadLen )
+    {
+        memcpy( &payload, message->payload, sizeof( TEST_OVERRIDE_PAYLOAD_T ) );
+        if ( FALSE == payload.reset )
+        {
+            result = testSetPendingACKOverride( payload.state.u32 );
+        }
+        else
+        {
+            result = testResetPendingACKOverride();
+        }
+    }
+
+    // Respond to request
+    sendTestAckResponseMsg( (MSG_ID_T)message->hdr.msgID, result );
+}
+
 /**@}*/
Index: firmware/App/Services/SystemCommMessages.h
===================================================================
diff -u -r0826b00090b65c16a3e52e006cc3c016a6bf6a08 -r97a93f387f6797fc747895fc915323220db12573
--- firmware/App/Services/SystemCommMessages.h	(.../SystemCommMessages.h)	(revision 0826b00090b65c16a3e52e006cc3c016a6bf6a08)
+++ firmware/App/Services/SystemCommMessages.h	(.../SystemCommMessages.h)	(revision 97a93f387f6797fc747895fc915323220db12573)
@@ -1010,6 +1010,9 @@
 // MSG_ID_HD_RAM_STATUS_OVERRIDE
 void handleTestHDRAMStatusOverrideRequest( MESSAGE_T* message );
 
+// MSG_ID_HD_CAN_RECEIVE_ACK_MESSAGE_OVERRIDE
+void handleTestHDPendingACKOverrideRequest( MESSAGE_T* message );
+
 /**@}*/
 
 #endif