diff --git a/McZapkie/MOVER.h b/McZapkie/MOVER.h
index 199c65a0c..a34d537f4 100644
--- a/McZapkie/MOVER.h
+++ b/McZapkie/MOVER.h
@@ -2461,9 +2461,15 @@ class TMoverParameters
 	{
 		return false == ControlPressureSwitch && (HasControlPressureSwitch || BrakePress < 1.0);
 	}
-	// whether the lamp of the open line contactors is lit, telling the start can be made
+	// whether the lamp of the open line contactors is lit. on the electric locomotives it tells the start can be made, so
+	// it goes out with the start cut off; on the diesel-electric ones (the SU45 and SU46 family) it just tells the
+	// contactors are open, whatever opened them: the master controller at 0, or the pressure switch (eu07/maszyna#263)
 	bool LineContactorsLampLit() const
 	{
+		if (EngineType == TEngineType::DieselElectric)
+		{
+			return false == StLinFlag;
+		}
 		return false == StLinFlag && MainCircuitLampsEnabled();
 	}
 	// whether the pumps a joint oil and fuel pump switch works, those not started automatically, are all switched on
diff --git a/tests/unit/data/diesel_electric.json b/tests/unit/data/diesel_electric.json
new file mode 100644
index 000000000..bef605880
--- /dev/null
+++ b/tests/unit/data/diesel_electric.json
@@ -0,0 +1,46 @@
+{
+  "_comment": "Diesel-electric locomotive made after the SU46 (303D): the line contactors close on the first power position of the master controller, the pressure switch (on by default) opens them with too low a pressure in the main pipe or the brakes applied.",
+  "Param": { "Category": "train", "M": 105000, "Mred": 15000, "Vmax": 120, "PWR": 1400, "SandCap": 400 },
+  "Dimensions": { "L": 18.99, "H": 4.292, "W": 2.904, "Cx": 0.3 },
+  "Wheels": { "D": 1.1, "AIM": 4000, "Tw": 1.435, "Axle": "Co'Co'", "Ad": 1.75, "Bd": 10.3, "Rmin": 100 },
+  "Brake": {
+    "BrakeValve": "LSt", "NBpA": 4, "MBF": 85.0, "MaxBP": 4.4, "LocMaxBP": 4.4, "MaxASBP": 1.3, "RM": 0.71, "BCN": 12, "BCR": 0.114,
+    "BCD": 0.06, "BCM": 5.84, "HiPP": 5, "LoPP": 3.5, "Vv": 0.9, "MinCP": 7, "MaxCP": 8.5, "CompressorSpeed": 0.05, "BCS": 1, "BSA": 2,
+    "BM": "P10-Bgu", "CompressorPower": "Converter", "BVV": 200, "BRE": 0.8
+  },
+  "BuffCoupl": { "CType": "Screw", "kB": 9200, "DmaxB": 0.15, "FmaxB": 740, "kC": 4800, "DmaxC": 0.15, "FmaxC": 780, "beta": 0.58, "AllowedFlag": 103 },
+  "Cntrl": {
+    "BrakeHandle": "FV4a", "LocBrakeHandle": "FD1", "BrakeSystem": "Pneumatic", "BDelay1": 15, "BDelay2": 6, "BDelay3": 36, "BDelay4": 32,
+    "ASB": "Manual", "LocalBrake": "PneumaticBrake", "MCPN": 15, "SCPN": 4, "AutoRelay": "Yes", "IniCDelay": 0.5, "SCDelay": 0.1,
+    "BrakeDelays": "GPR", "ConverterStart": "Automatic", "ConverterStartDelay": 10
+  },
+  "Light": { "Light": "Generator", "LGeneratorEngine": "ElectricSeriesMotor", "LMaxVoltage": 110, "LMaxCurrent": 100 },
+  "Engine": {
+    "AIM": 1.6, "EngineType": "DumbDE", "Trans": "18:62", "Ftmax": 317000, "Flat": 0, "Vhyp": 15.0, "Vadd": 3.8, "Cr": 1.0, "RelayType": 46,
+    "OilMinPressure": 0.055, "OilMaxPressure": 0.6, "WaterMinTemperature": 40, "WaterMaxTemperature": 92, "WaterCoolingTemperature": 76,
+    "HeatKW": 0.068599, "HeatKV": 0.3, "HeatKFE": 1, "HeatKFS": 87.76269, "HeatKFO": 26.72716, "HeatKFO2": 57.72
+  },
+  "Circuit": { "CircuitRes": 0.01, "ImaxLo": 3300, "IminLo": 2500 },
+  "_power": "rows: engine speed [rpm], power [kW], generator voltage limit, current limit, one per master controller position",
+  "WWList": {
+    "Size": 15,
+    "rows": [
+      [696, 0, 0, 0],
+      [696, 0, 0, 0],
+      [696, 80, 350, 1000],
+      [696, 80, 350, 1000],
+      [763, 214, 455, 1400],
+      [830, 321, 500, 1600],
+      [897, 428, 545, 1800],
+      [964, 535, 590, 2000],
+      [1031, 642, 635, 2200],
+      [1098, 748, 680, 2400],
+      [1165, 855, 725, 2600],
+      [1232, 962, 770, 2800],
+      [1299, 1069, 815, 3000],
+      [1366, 1176, 865, 3200],
+      [1433, 1283, 910, 3400],
+      [1500, 1390, 960, 3600]
+    ]
+  }
+}
diff --git a/tests/unit/test_line_contactors.cpp b/tests/unit/test_line_contactors.cpp
index 79c419edf..fd7e24f08 100644
--- a/tests/unit/test_line_contactors.cpp
+++ b/tests/unit/test_line_contactors.cpp
@@ -57,3 +57,74 @@ TEST_CASE("line contactors: the ground relay and overload lamps follow the same
 	vehicle->MotorConnectorsCheck();
 	CHECK_FALSE(vehicle->MainCircuitLampsEnabled());
 }
+
+// on the diesel-electric SU45 and SU46 (eu07/maszyna#263) the lamp tells just the line contactors are open: lit with the
+// master controller at 0 and with the start cut off by too low a pressure in the main pipe, out on the power positions
+
+namespace {
+
+// the diesel-electric locomotive with its engine running and the brakes released, the master controller at 0
+test::vehicle diesel_electric() {
+	test::vehicle vehicle{test::definition::load("diesel_electric")};
+	vehicle->CabOccupied = 1;
+	vehicle->CabActivisation();
+	vehicle->BatterySwitch(true);
+	vehicle->OilPumpSwitch(true);
+	vehicle->FuelPumpSwitch(true);
+	vehicle.run(20.0); // the oil pressure builds up
+	vehicle.hold_brake_pipe(5.0); // bar
+	vehicle->MainSwitch(true);
+	vehicle.run(30.0);
+	vehicle->DirectionForward();
+	vehicle.run(60.0); // the brakes release
+	return vehicle;
+}
+
+} // namespace
+
+TEST_CASE("line contactors: on a diesel-electric the lamp is lit at 0 and goes out on a power position") {
+	auto vehicle{diesel_electric()};
+	REQUIRE(vehicle->EngineType == TEngineType::DieselElectric);
+	REQUIRE(vehicle->Mains);
+	REQUIRE_FALSE(vehicle->ControlPressureSwitch);
+	CHECK_FALSE(vehicle->StLinFlag);
+	CHECK(vehicle->LineContactorsLampLit());
+
+	vehicle->IncMainCtrl(1);
+	vehicle.run(3.0);
+	CHECK(vehicle->StLinFlag);
+	CHECK_FALSE(vehicle->LineContactorsLampLit());
+
+	vehicle->DecMainCtrl(1);
+	vehicle.run(3.0);
+	CHECK_FALSE(vehicle->StLinFlag);
+	CHECK(vehicle->LineContactorsLampLit());
+}
+
+TEST_CASE("line contactors: on a diesel-electric the lamp lights with the contactors opened by too low a main pipe pressure") {
+	auto vehicle{diesel_electric()};
+	vehicle->IncMainCtrl(1);
+	vehicle.run(1.0);
+	vehicle->IncMainCtrl(1);
+	vehicle.run(2.0);
+	REQUIRE(vehicle->StLinFlag);
+
+	vehicle.hold_brake_pipe(2.5); // bar, below the 3.6 bar of the pressure switch
+	vehicle.run(10.0);
+	REQUIRE(vehicle->ControlPressureSwitch);
+	CHECK_FALSE(vehicle->StLinFlag);
+	CHECK(vehicle->LineContactorsLampLit()); // it went out here
+	CHECK_FALSE(vehicle->MainCircuitLampsEnabled()); // the ground relay and overload lamps still go out with the start cut off
+
+	// the pressure back, the contactors stay open on the second position and the lamp stays lit, as it should;
+	// they close again only on the first one
+	vehicle.hold_brake_pipe(5.0);
+	vehicle.run(60.0);
+	REQUIRE_FALSE(vehicle->ControlPressureSwitch);
+	CHECK_FALSE(vehicle->StLinFlag);
+	CHECK(vehicle->LineContactorsLampLit());
+	vehicle->DecMainCtrl(1);
+	vehicle.run(3.0);
+	CHECK(vehicle->StLinFlag);
+	CHECK_FALSE(vehicle->LineContactorsLampLit());
+}