The eBay keyless units are all universal and can be set up to suit different cars at installation. Most of the wires can be ignored, e.g. you don't need it bibbing the horn, flashing the indicators and closing the windows so the simplest units are probably the best, and you won't need actuators either.
Using wires from the drivers door key lock, the white wire is temporarily grounded to unlock, the white/red is temporarily grounded to lock the central locking, so follow the set up instruction in the kit for 'pulse low' or 'negative trigger'.
This connects to the loom from the drivers door that pass through the footwell area next to the fusebox. There is space to hide the receiver behind the panel to the right of the fusebox (which is where the original receiver would live).
The existing wiring is quite tight and you'll need to spend an hour with your head stuck in the footwell, but quite a few people have done this.
From drivers key mechanism and taken momentarily to ground (black):
White = Unlock
White/red = Lock
Quite a few choices to get permanent 12v and ground nearby.http://www.hondafitjazz.com/manual
> wiring diagrams > power door lock system
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Shouldn't need to take off the door panel, the wiring can be done from the footwell. The panel above the pedals is the most useful to remove (twist clip + 2 friction clips along front edge) and it might help to take out the fusebox cover (unclips) and the trim that surrounds it (screws + clip). The wiring diagrams from before will help you find one of the 12v wires and you can use a bolt for the ground connection
There's also a useful connector for the door wiring hidden by the trim around the bonnet release lever.
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The door wires for locks, windows and mirrors pass through the rubber grommet then down to a grey and blue connector in the footwell. You should find a white/red and a white with silver grey blobs next to it on the grey connector (circled in image).
Remember leave a window open and to disconnect battery
if you are going to start joining to these cables, there will be 12v present at all times as the driver's door keyswitch temporarily connects them to ground.
Power the unit via one of the existing fuses with a fusetap.
- - -Kit wires >>> Car wires
Yellow & yellow/black & black >>> ground (0 volts), i.e. under a bolt
Red >>> permanent 12v via a fuse
White >>> white/red (lock)
White/black >>> white (unlock)
Note that white does not connect to white. (although at least one kit has the lock & unlock buttons swapped over)
Just connect the red and black power wires first to test if it receives the signal from the remote. If that seems OK, move on to the (un)locking.
Probably a good idea to make sure there is no exposed cores of the other spare wires able to contact anything so tape them up.
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Looking at the car's horn and indicators / hazard light control circuit most of it is quite buried without removing further bits of trim, but the rear indicator lights cabling runs down the drivers side of the car and can be traced from the footwell. The indicators take quite a lot of power (21w + 5w + 21w) x 2 = 94w so it's seems beneficial that the two brown wires from the kit are fairly thick. You can connect one brown wire to the left hand indicators and the other brown wire to the right hand indicators, but they will need to be good connections to support the potential current draw.
The circuit diagram shows green/yellow for RH indicators and green/red for LH indicators, you could trace back the cable bundle that runs along the drivers sill to find where the connections are made to the under dash fusebox. (It's also a junction box with connections on both sides).
I'm not certain what the siren/horn connection will achieve, bibbing the horn when locking or unlocking is not much use. If it's for a panic alarm that might be worth it. You can hear the locks operate from quite a distance so that's all you really need to be sure it's working.
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So, the indicators lights were connected on separate harness marked.
After connecting the brown wires from the kit, all working perfectly as expected!!