Hi fellows. Due to not being able to use the cheap American trailer-hitch boxes (too little wires), and them being bloody expensive here, I'm building my own. Supposedly the Prius doesn't have a wining canbus and can support the extra lights in parallel to the normal brake/indicator/etc. lights, but it doesn't feel right. I tried designing them with electronics, but you will always have a voltagedrop with normal transistors and fets also are tricky with such 'low' voltages. So decided on relais. they draw 30mA, so it's peanuts. My questions: - is it correct we have 2 fog-lights? Are they both on the same circuit and fuse? Our trailer-hitch sockets often have an auto-disconnect when a plug is jammed in there, so you're not constantly staring into the glow of the foglights reflecting of off the trailer. But I'll have to cut both fog-light-power-feeds and parallel them through this switch and back to the lights. - can I find an accessory wire somewhere in the rear? If I don't need the 6th relais for the foglights, I'm reserving it for a switched power which should only come ON when the car is in ready-mode. Even considering adding a 30 second delay so it doesn't interfere with the start-up current during getting "Ready".
What exactly are you trying to build? If you don't NEED an accessory, and just want parking / brake / turn lights, and you're not going to be drawing a lot of current with your own hitch-box lights, you can simply piggy-back on the tail light circuit. This is what I did with my travel trailer... just tapped into the brake and turn lights in the rear with a wiring kit (no relays or +12V power needed) and used the same signals to drive my trailer lights (2x side lights + 2x tail lights). I haven't blown any fuses or seen any problems with dim lights...
No, I don't *need* the accessory, but I like making it fancy I have a 13 pole socket and it would be a waste only to use half (we have standardized 7 and 13 pin plugs, I happened to run into this cheap 13 pin socket and my other car is also 13 pin) BTW, the +12V would be fused with 20A and the accessory with an extra 10A thermal, resetable fuse. BTW, my Volvo has (guestimate) ~23AWG wiring for the 60W headlights so wouldn't even consider paralleling anything on that, but I think the Prius wiring has some more 'headroom'.But still doesn't feel right to add a ~50W draw without any upgrade on wiring/fusing. Just worked on it today, so it's almost done (wiring it up will be another matter though). Will post a pic shortly incase anyone's interested of a pic of 6 relays in a box
I don't know about trailers in NL, but in the US if you want trailer lights just buy this Plug N Play wiring harness. No cutting/splicing of wires, and it connects to the 12V battery directly to supply plenty of current for any kinds of lights on your trailer and does not add any load to the Prius lamp circuits. Uses standard North American 4 pin flat trailer connector. Kit installs in 20 minutes and car can easily be "put back to stock" if you sell the car. Custom Fit Vehicle Wiring by Tow Ready for 2009 Prius - 118505
Thanks. I wish... But we have separate indicators, whereas the indicators in the US are the same as the brakelights, correct? So I would not be able to use that box, sadly enough (we have 5 wires + 1 ground in our standard plug). I also searched for the pass-through connectors and even mailed EVnut about the connectors he used (link) but I cannot get hold of the connectors, nor did he know where to get them now. So that's why I started this project and am, sadly enough, forced to hack into the existing wiring. Not willingly, but I see no alternative (but am open to ideas!!!) I would very much like to know HOW they did it though, seeing the size of the box, I think they used electronics instead of relays, so they seem not to have my (perceived) problem of voltage-drop to the lights.
