diff --git a/Config/ProjectApollo/SaturnSystems.cfg b/Config/ProjectApollo/SaturnSystems.cfg
index f1269552e1..f2f811efdf 100644
--- a/Config/ProjectApollo/SaturnSystems.cfg
+++ b/Config/ProjectApollo/SaturnSystems.cfg
@@ -1240,6 +1240,7 @@
 		HYDRAULIC:FUELCELLRADIATOR8 150.0
 	</COOLING>
 
+	# Ext Lighting
 	<LIGHT> SPOTLIGHT DC_DUMMY 0 0.0 0.0 <-1.439 1.390 0.920> <0.0045 -0.0046 0.9999> 5000.0 0.0 0.0 0.0015 0.174533 0.5 <1.0 0.945 0.878 0.0> <1.0 0.945 0.878 0.0> <0.0 0.0 0.0 0.0> 100.0 115.0
 	<LIGHT> RNDZLIGHT DC_DUMMY 1 0.02 0.98 <-0.490 -1.975 0.920> <0.0 -0.866 0.5> 5000.0 0.0 0.0 0.0015 2.094 3.142 <1.0 1.0 0.950 0.0> <1.0 1.0 0.950 0.0> <0.0 0.0 0.0 0.0> 10.0 28.0
 
diff --git a/Orbitersdk/samples/ProjectApollo/src_csm/eps.cpp b/Orbitersdk/samples/ProjectApollo/src_csm/eps.cpp
index 4e7a2ed1e9..719b79a162 100644
--- a/Orbitersdk/samples/ProjectApollo/src_csm/eps.cpp
+++ b/Orbitersdk/samples/ProjectApollo/src_csm/eps.cpp
@@ -198,4 +198,54 @@ void CryoPressureSwitch::SaveState(FILEHANDLE scn, char *name_str)
 
 	sprintf(buffer, "%d %d", PressureSwitch1, PressureSwitch2);
 	oapiWriteScenario_string(scn, name_str, buffer);
+}
+
+ExteriorLighting::ExteriorLighting()
+{
+	saturn = NULL;
+	SpotDeployed = false;
+	EVALtDeployed = false;
+}
+
+ExteriorLighting::~ExteriorLighting()
+{
+
+}
+
+void ExteriorLighting::Init(Saturn *s, CircuitBrakerSwitch *MNB, ThreeSourceTwoDestSwitch *RDZSPOT)
+{
+	saturn = s;
+	RNDZSPOTMNBcb = MNB;
+	RDZSPOTsw = RDZSPOT;
+}
+
+void ExteriorLighting::SystemTimestep(double simdt)
+{
+	if (!saturn->LETAttached())
+	{
+		EVALtDeployed = true;
+	}
+
+	if (RDZSPOTsw->IsDown() && RNDZSPOTMNBcb->IsPowered())
+	{
+		SpotDeployed = true;
+	}
+}
+
+void ExteriorLighting::LoadState(char *line, int strlen)
+{
+	int i, j;
+
+	sscanf(line + strlen + 1, "%i %i", &i, &j);
+
+	SpotDeployed = (i != 0);
+	EVALtDeployed = (j != 0);
+}
+
+void ExteriorLighting::SaveState(FILEHANDLE scn, char *name_str)
+{
+	char buffer[100];
+
+	sprintf(buffer, "%d %d", SpotDeployed, EVALtDeployed);
+	oapiWriteScenario_string(scn, name_str, buffer);
 }
\ No newline at end of file
diff --git a/Orbitersdk/samples/ProjectApollo/src_csm/eps.h b/Orbitersdk/samples/ProjectApollo/src_csm/eps.h
index a2284f6edd..23528f0f10 100644
--- a/Orbitersdk/samples/ProjectApollo/src_csm/eps.h
+++ b/Orbitersdk/samples/ProjectApollo/src_csm/eps.h
@@ -50,4 +50,24 @@ class CryoPressureSwitch
 	bool PressureSwitch2;
 	double lowpress;
 	double highpress;
+};
+
+
+/// This class simulates exterior lighting behavior in the CSM
+class ExteriorLighting
+{
+public:
+	ExteriorLighting();
+	virtual ~ExteriorLighting();
+	void Init(Saturn *s, CircuitBrakerSwitch *MNB, ThreeSourceTwoDestSwitch *RDZSPOT);
+	void SystemTimestep(double simdt);
+	void SaveState(FILEHANDLE scn, char *name_str);
+	void LoadState(char *line, int strlen);
+
+protected:
+	Saturn *saturn;
+	CircuitBrakerSwitch *RNDZSPOTMNBcb;
+	ThreeSourceTwoDestSwitch *RDZSPOTsw;
+	bool SpotDeployed;
+	bool EVALtDeployed;
 };
\ No newline at end of file
diff --git a/Orbitersdk/samples/ProjectApollo/src_csm/satsystems.cpp b/Orbitersdk/samples/ProjectApollo/src_csm/satsystems.cpp
index 3d76782d92..504e476873 100644
--- a/Orbitersdk/samples/ProjectApollo/src_csm/satsystems.cpp
+++ b/Orbitersdk/samples/ProjectApollo/src_csm/satsystems.cpp
@@ -139,12 +139,14 @@ void Saturn::SystemsInit() {
 	FuelCellN2Blanket[2] = (h_Tank *)Panelsdk.GetPointerByString("HYDRAULIC:N2FUELCELL3BLANKET");
 
 	//
-	// Electric Lights
+	// Exterior Lights
 	//
 
 	SpotLight = (ElectricLight *)Panelsdk.GetPointerByString("ELECTRIC:SPOTLIGHT");
 	RndzLight = (ElectricLight *)Panelsdk.GetPointerByString("ELECTRIC:RNDZLIGHT");
 
+	ExteriorLighting.Init(this, &LightingRndzMNBCB, &RndzLightSwitch);
+
 	//
 	// EPS/Cryo devices
 	//
@@ -1862,6 +1864,7 @@ void Saturn::SystemsInternalTimestep(double simdt)
 		EventTimer306Display.SystemTimestep(tFactor);
 		H2CryoPressureSwitch.SystemTimestep(tFactor);
 		O2CryoPressureSwitch.SystemTimestep(tFactor);
+		ExteriorLighting.SystemTimestep(tFactor);
 
 		simdt -= tFactor;
 		tFactor = __min(mintFactor, simdt);
diff --git a/Orbitersdk/samples/ProjectApollo/src_csm/saturn.h b/Orbitersdk/samples/ProjectApollo/src_csm/saturn.h
index 201e0659e4..337730b520 100644
--- a/Orbitersdk/samples/ProjectApollo/src_csm/saturn.h
+++ b/Orbitersdk/samples/ProjectApollo/src_csm/saturn.h
@@ -1902,9 +1902,9 @@ class Saturn: public ProjectApolloConnectorVessel, public PanelSwitchListener {
 	ThreePosSwitch TVCGimbalDriveYawSwitch;
 
 	SwitchRow CSMLightSwitchesRow;
-	ToggleSwitch RunEVALightSwitch;
+	TwoSourceSwitch RunEVALightSwitch;
 	ThreeSourceTwoDestSwitch RndzLightSwitch;
-	ToggleSwitch TunnelLightSwitch;
+	TwoSourceSwitch TunnelLightSwitch;
 
 	SwitchRow LMPowerSwitchRow;
 	CSMLMPowerSwitch LMPowerSwitch;
@@ -3835,6 +3835,9 @@ class Saturn: public ProjectApolloConnectorVessel, public PanelSwitchListener {
 	ThreePhasePowerMerge SuitCompressor1Feeder;
 	ThreePhasePowerMerge SuitCompressor2Feeder;
 
+	// Exterior Lighting
+	ExteriorLighting ExteriorLighting;
+
 	// GSE
 	Pump* GSEGlycolPump;
 	h_Radiator* GSERadiator;
diff --git a/Orbitersdk/samples/ProjectApollo/src_csm/saturnpanel.cpp b/Orbitersdk/samples/ProjectApollo/src_csm/saturnpanel.cpp
index b5cdfdfcfb..1e797de396 100644
--- a/Orbitersdk/samples/ProjectApollo/src_csm/saturnpanel.cpp
+++ b/Orbitersdk/samples/ProjectApollo/src_csm/saturnpanel.cpp
@@ -1860,9 +1860,9 @@ void Saturn::SetSwitches(int panel) {
 	TVCGimbalDriveYawSwitch.Init  (43, 0, 34, 29, srf[SRF_THREEPOSSWITCH], srf[SRF_BORDER_34x29], TVCGimbalDriveSwitchesRow);
 
 	CSMLightSwitchesRow.Init(AID_CSMLIGHTSWITCHES, MainPanel);
-	RunEVALightSwitch.Init(  0, 0, 34, 29, srf[SRF_SWITCHUP], srf[SRF_BORDER_34x29], CSMLightSwitchesRow);
-	RndzLightSwitch.Init( 57, 0, 34, 29, srf[SRF_THREEPOSSWITCH], srf[SRF_BORDER_34x29], CSMLightSwitchesRow, &RunEVATRGTAC2CB, NULL, &LightingRndzMNACB, RndzLight, SpotLight);
-	TunnelLightSwitch.Init(111, 0, 34, 29, srf[SRF_SWITCHUP], srf[SRF_BORDER_34x29], CSMLightSwitchesRow);
+	RunEVALightSwitch.Init(0, 0, 34, 29, srf[SRF_SWITCHUP], srf[SRF_BORDER_34x29], CSMLightSwitchesRow, &RunEVATRGTAC1CB, &RunEVATRGTAC2CB);
+	RndzLightSwitch.Init(57, 0, 34, 29, srf[SRF_THREEPOSSWITCH], srf[SRF_BORDER_34x29], CSMLightSwitchesRow, &RunEVATRGTAC2CB, NULL, &LightingRndzMNACB, RndzLight, SpotLight);
+	TunnelLightSwitch.Init(111, 0, 34, 29, srf[SRF_SWITCHUP], srf[SRF_BORDER_34x29], CSMLightSwitchesRow, &LightingRndzMNACB, &LightingRndzMNBCB);
 
 	LMPowerSwitchRow.Init(AID_LMPOWERSWITCH, MainPanel);
 	LMPowerSwitch.Init( 0, 0, 34, 29, srf[SRF_THREEPOSSWITCH], srf[SRF_BORDER_34x29], LMPowerSwitchRow, this);