Sunday Danday (Cane therapy for the stubborn dirt and grime over a week's time) on Megalodon - woke up early and decided to get things straight. After the UV and paint protect treatment, there is no need to scrub so much, just pour some water and the muck from the rains just slips away. I was told this will hold true for the next 6 months or so - however I will try and not get carried away with this and will abide by the fixed Sunday Waxing Schedule.
Then thought of utilizing the time for installing the dual horn system. I really felt that there was a need for bigger horns on the highway as the stock ones were not audible enough. Here is the pictoral explanation of the DIY dual horn install for the 2012 Toyota Fortuner.
Before I proceed, I would like to inform you to be extremely careful as you are handling the electrical system of your vehicle. Do not splice or cut any wires before checking it with a test lamp. Cutting wires might also void warranty. I have done this install on my own risk having faith on Toyota that they have done a through QC on Megalodon.
Tools required:
+ point screwdriver
Size 10 T Spanner
Size 12 T Spanner
Wire cutter and stripper
12V Line tester
Topaz (or similar) shaving blade
A butterknife. This will be used to remove the trim panels.
Here is the set of Roots vibrosonic that I have to install.
This is the place from where I have chosen to get the wires in from the cabin to the engine bay. There is a small grommet near the ECU that gives a direct access to the cabin behind the glove box. There are 3 wires running in from here. There is a red 10sqmm wire for powering the amp (Next Sunday's plan), there is a yellow wire 2.5 sqmm which carries the trigger from the 3 point horn relay to the horns. There is a red 2.5sqmm supply wire (10A fused) for supplying the +ve from battery to the horn relay. I have laid additional wiring for the additional horns and am not disturbing the stock wiring. The only wire that needs to be cut is a horn pad trigger wire. This is a supply wire to the relay and not the load (horns).
Spliced the grommet from the center of about 1mm (size) triangle. It will be a task to insert wires form this, but it is necessary as you dont want water to enter the cabin from here. There is a heat sheild fabric right behind the grommet and if that will get wet - there will be a foul smell in the cabin and you might not recollect where this is coming from. It is important to use the grommet, if you dont use it, there is a possibility over a period of time and constant contact with steel body the wires may cut and will come in contact with the body which is 'earthed' and your wires are carrying +ve supply.
Place where the 2 way switch will be located.
Place where the new relay will be placed. Its inside the cabin so no bother of the relay not working due to water spalsh of any kind. Located behind the glove box compartment. Will use the size 10 nut welded to the body to fix the relay.
It is better if you remove the USB trim as well as the wires will be running behind it. You need to be sure that the wires are not coming in contact with any movable parts.
Three screws need to be removed, two on the either side of the steering wheel and one below the steering adjust lever. Carefully remove the key fob cover and all the steering wheel wires will be exposed.
Left one near the wiper stalk.
Right one near the headlight stalk.
Third one below the steering adjustment lever.
Once the wires are exposed - you will observe that there are many sockets. There are many white ones, only one yellow and only one black. White ones are for the stalks and the steering wheel control buttons. Do not touch the yellow socket as it is for the SRS airbag. We will only use the black socket as it is the power supply socket to the steering wheel. How do I know that this is power supply socket? Simple, remove the socket and press horn. Nothing happens - problem solved. Usually, there is a horn pad and there are some contact points from the wheel that touch this pad. These contact point terminals are supplied from the battery (through the fuse box) and this charges the horn pad. there is a wire from the horn pad which carries the contact point trigger and goes to a relay which will convert the negative trigger to a +ve trigget. Logic remains the same its just that different manufacturers use different types of charges (+ve supply or earth) and relays.
On the black socket, there is a white wire with a red stripe. This is the wire which carries the trigger from the horn pad to the horn relay. I had checked it with the test lamp method. Its like this - connect one end of the test lamp to battery and the other end is connected to a shaving blade. Now touch the wires with the blade. If there is a 'like' charge, the bulb will not glow. If the bulb glows it means that this wire carries an earth charge. So for all the wires that did not glow, I pressed the horn pad on the steering wheel and on this white and red stripe wire, the bulb only glowed when the horn was pressed. Mission Accomplished. (For other vehicles, if you dont still get the trigger wire, change the polarity of the test lamp and repeat the process). This wire needs to be cut and the wire coming in from the socket end goes to the 'LOAD' of the 2 way switch. Other end of the striped wire goes to either +ve or -ve end of the 2 way switch. Supply to the new horn relay goes from the remaining +ve or -ve of the 2 way switch. You will need additional wires to connect the striped wire to the 2 way switch.
Grill was removed so that there was a decent access to the member area. Also better to remove it so as to avoid accidental scratches on the chrome grill. This is how the horns were placed without disturbing the stock horns.
Grommet back in place. Took a little effort but then its in shape. All wires are travelling to the battery and horns from behind the fender.
My local jugad of a test lamp ! Very Very handy in such types of installs.
3 Point relay in its final position. 10 sqmm red wire is bundled and will be used in the next week when I will install the ICE.
2 Way switch in its place.
Everything is working hunky dory
After this install, which took almost an hour, washed and waxed Megalodon and end of it all - me happy happy !