Making The Alarm Horn Louder:

This is a simple modification you can do to all MK1 mondeos to make the alarm horn louder. The mondeo's alarm horn is located (for a reason known only to some designer at ford) inside the cabin, behind the sound deadening material and carpet of the boot. As a result of all the sound proofing it produces a rather pathetic beep noise which isn't nearly loud enough in a busy carpark. This how-to explains how to incorporate your front car horn(s) into the alarm system.

If your model spec is GLX or below then you will only have one horn as standard - to maximise output its recommended that you upgrade your existing horn to twin's. To do this you need to get a second horn from a scrapped mondeo and install it in the mounting position (RHS - Next to screen wash bottle). You then need to run a cable from the single connector on top of it, accross the engine bay to your original horn (LHS), and splice into the cable supplying that horn. If you have a higher spec level then you will probably have this second horn already installed.

The mondeo horn is permanently live, meaning that you can use it with or without a key. Its also fed via a relay so there is no security risk associated with connecting to it. However its switched negatively which causes a few small problems and requires a relay to overcome them.

All of the wiring shown in black is existing, the blue wiring (and relay) you need to add.

How This Circuit Works:

When the alarm activates it sends a 12V pulse out of pin 4 on connecton C451a. This pulse makes the alarm horn H5 activate and beep. We can use this 12V feed to energise a new relay by taking a splice just before the alarm horn (Connection Point 1). Grounding the other end of the relay's coil makes the relay energise and de-energise in time with the pulses from the alarm system (Connection Point 2). The other side of the relay acts as switch, so by taking one pin to ground (Also Connection Point 2) and the other pin to (Connection Point 3) we get a ground pulse being applied to horn switch - just as if the steering wheel's horn button had been pressed. This in turn energises the existing K33 Horn relay and makes both front horns beep in time with the alarm.

Be aware that Ford didn't do this because the effect of all three horns activating exceeds the noise level allowed by UK law for alarm systems.

Connection Point 1 > On the left side of the boot, behind the wall carpet. Splice into the Orange/Green cable supplying the alarm horn.

Connection Point 2 > Use an O or P Crimp connector and use the ground bolt of the existing alarm horn.

Connection Point 3 > Locate the connector C11 (Mk1) above the passenger fusebox and connect to the Black/Blue cable on Pin 16.