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The PROTECTOR TWO Alarm and Light Controller consists of a control box and two key fobs, a ceiling mounted PIR, a rear leg sensor and a siren. So there are not many parts to go wrong and all of them can be changed easily. At the end of this guide the procedures for changing these parts is given. The alarm also remotely switches the awning light using the second button on the fob.

Most faults can be identified in a short time by doing the following:-

1 Check that the ceiling mounted PIR lights red when you move under it (control box key switch can be either on or off). If the PIR lights red go to step 3

2 If the PIR does not light red remove the lens cover and use a Voltmeter to check that 12 Volts is present on the 12V terminals (often the red and black wires). If 12 Volts is present then the PIR is faulty and should be replaced. If 12 Volts is not present then either the fuse in the control box is blown or there is a break in the wiring.

3 Turn the key switch to the ON position (clockwise); the siren should "cheep" once. If the siren cheeps once go to step 5.

4 If the siren does not cheep the fault is either the control box, the siren or the wiring. BUT FIRSTLY CHECK THAT THE CORRECT FOBS ARE WITH THE CONTROL BOX. The serial numbers on the back of the fobs should be the same as the serial number on the underneath of the control box. If you have a spare control box, unplug the original box and plug in the spare box. To check the siren disconnect its wires from the caravan wiring and then connect the siren across the Leisure battery (or a good 9 Volt PP3 battery). If the siren makes the normal sound then it is OK. To check the wiring connect a Voltmeter across the siren terminals, arm the alarm with the key fob, then move under the PIR. The LED on the control box should change from flashing once a second to flashing 3 times, pausing, flashing 3 times, pausing etc. You then have the next 2 minutes to check whether the 12 Volt feed is getting to the siren terminals.

5 Press the ALARM button on the key fob, siren should "cheep" twice, press again siren cheeps once. Press the ALARM button once, siren cheeps twice, now move under the PIR. Alarm should sound instantly. Press ALARM button once to silence the siren. If this is OK go to step 7.

6 If moving under the PIR did not cause the siren to sound the fault is probably the PIR. Replace it and test again. If the siren then does not trigger, replace the control box.

7 Go outside the van, close the door and then press ALARM button once; the siren "cheeps" twice. Using a leg winder tool turn the alarmed rear leg spindle one turn, the siren should sound instantly. If the siren sounds then go to step 9.

8 If winding the alarmed leg does not sound the siren, firstly check you are winding the correct leg. Then with the alarm armed (after 2 cheeps) try shorting the two wires going to the leg sensor. This should trigger the siren provided that the magnet is away from the reed switch (i.e. the two white blocks are away from each other). If shorting the wires triggers the siren then the leg sensor should be changed. If shorting the wires does not sound the siren then change the control box. If the fault persists then check the wiring between the control box and the leg sensor.

9 Still outside the van with the door shut press the ALARM button to arm the alarm. After the two "cheeps" take the 13 pin plug and insert it into a tow vehicle or test box. The siren should sound immediately. With the plug inserted, operating the foot brake should trigger the alarm. If not change the control box or check the wiring.

10 The AWNING LIGHT is controlled by the second button on the key fob. Early Lunar caravans were wired with the switch inside the caravan connected in parallel with the switch in the alarm box. This means that both switches must be in the off position to turn the light off. The awning light on some caravans may glow dimly when switched off. This is caused by a very small leakage current (0.000025 Ampere) flowing through the alarm box. Later caravans were wired correctly, with the awning light switch in the caravan in series with the feed to the awning light. Then switching the awning light off with the switch in the caravan would ensure that the light is off. With the switch in the caravan on, the awning light can be switched on and off by successive presses on the key fob’s light button.

If you cannot solve the problem within half an hour please phone me on 01296 423 203 for advice.


These can be very annoying, especially if they don’t happen very frequently. Fortunately the alarm has its own diagnostic software, this displays which sensor circuit has caused the false alarm. When the alarm control box is turned on with the key, the siren cheeps once and the red LED on the box is unlit. When the alarm is armed using the key fob, the siren cheeps twice and the red LED on the box starts flashing regularly once a second. When the alarm is disarmed using the key fob the LED stops flashing. If when the alarm is armed an alarm occurs two things happen. 1) The siren sounds for 2 minutes, or until turned off with the key fob. 2) The red LED starts flashing several times, pauses, flashes the same number of times, pauses, etc. The alarm can be armed and disarmed any number of times, but the LED will continue to flash the same number of times.

The below table details which sensor triggered the alarm.

Regular flashing - Alarm on

1 flash – panic alarm

2 flashes - Leg Sensor

3 flashes - PIR

4 flashes - 12 or 13 pin plug circuit

5 flashes - disconnection of leisure battery


Control box - remove fixing screws and then remove 12 pin plug. Fit new box and insert plug.
To change the fuse in the control box - run a thumb nail under the plastic case base to separate it from the case top. Lift the case top to access the fuse on the PCB.

PIR - IMPORTANT NOTE unplug control box before continuing. This prevents you from accidentally blowing the fuse in the control box. Using a piece of masking tape, or a non permanent marker pen, make a mark on the top “saucer” and a corresponding mark on the bottom “saucer”. Then "pop off" the lens cover using a wide flat bladed screwdriver, note which colour wire goes to which terminal then remove the three wires. Undo single small screw holding printed circuit board (PCB) in place. Remove PCB and replace with PCB from a new PIR, re-connect the 3 wires. Press the lens cover back on, using your marks to ensure that the keyway inside the Saucers” is lined up. Note that the LED inside the PIR will flash for several minutes when power is first applied. This is normal, as this time period allows the pyro electric sensors to stabilise.

Leg Sensor - remove two wires from terminal block, remove two screws holding bracket to floor of van. Fit new leg sensor, re-connect wires then check that when winding the leg spindle the magnet passes within 2 to 4mm of the reed switch on the bracket.

Siren - disconnect the two wires, noting that the polarity is important. Remove two bolts from U shaped bracket. Remove new siren body from its U bracket and fit into van, then re-connect the wires.

For more information please refer to the OPERATING INSTRUCTIONS and the INSTALLATION INSTRUCTIONS