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How to connect LED spotlights through hi-beam to 2018 Rav4


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I have two LED spotlights mounted to a nudge bar on my 2018 Rav4 but Im getting a variety of mixed information on how to get them connected through a separate switch in with my high beam.

I'm getting a variety of comments,..including.....What is a Canbus unit,.. I need a 'Canbus' unit,......I need to BUY a Canbus unit,....the Rav already HAS a Canbus unit,....the Rav DOESNT have a Canbus unit.?....They must go through a Canbus unit or it could blow the 'on board computer'.. etc, etc, .. Definitely inferring that it is NOT a simple exercise to carry out.

 Checking with auto electricians,..its been impossible so far to find one confident enough to tackle it,..for fear of damaging the on board computer. ........which is perhaps WHY the one who DID say that he could wire it up (I already have the lights fitted, the switch is fitted and already connected up as a direct separate negative earth through its own separate fuse,.......which of course is illegal.)...said that it woukd cost me $800 to $900 ,...which absolutely tells me that he doesn't want to do it because those numbers are ridiculous.

I just want to have my lights connected up correctly by someone who knows his to do it,.......which could be ME, if I have an accurate diagram............Google was hopeless.

Thanks in advance.......



Edited by brickpaver
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Hi Lance,

I would use hard wiring, connecting to the high beam wire at the light The attached circuit shows how I would wire it. The hi beam controls one side of the relay, so when you dip, the relay releases and the spot goes off. The other end of the relay is connected to ground through the  dash switch, which then controls whether the spot comes on at all. One of the relay contacts goes directly to the battery, via a fuse, near the battery. The other contact goes to the spot. The spot is grounded normally. No CANBUS involved.



Spot light.jpg

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Herb,,..you've hit on exactly the way that I would initially have done it myself but I've been somewhat afraid and warned of damaging the computer ( apparently a very expensive repair/ replacement should it be damaged by being wired incorrectly)...particularly this 'Canbus' unit.

 It would seem that Toyota severely discourage anyone interfering with their intricate wiring looms, especially with anything that goes through the computer.

Definitely no criticism intended here because I would have done just about the very same procedure as that that you mentioned ,.....until I got the same info from several sources, warning me of the consequences around this Canbus unit,..which I had NEVER heard of before.

I've wired up many many spotlights on to all my cars over past decades,..lights  relay and switch,..hooked to the high beam feed off of the headlight high beam wire and all worked perfectly but of course all of those were easy,... being all negative earth vehicles.....but this Rav4 Is supposedly a different kettle of kippers as far as the wiring loom is concerned.

I guess I'm hoping to find someone with a 2018 Rav who has fitted spotties and could walk me through it. 😀

 i do appreciate your reply though.

  Lance S

Edited by brickpaver
Didn't finish it before.
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Hi Lance,


I may have been a bit premature, with my answer. I haven't studied CANBUS, but from early theoretical discussions it is a power bus running around the car, with a set of comms wires to controllers, that tap into the power bus. An ECU tells the controller to turn on or off the item. It is also a communications system between various ECUs in the car.


In bed last night I remembered seeing ads for CANBUS LEDs, and was wondering if the control chip is imbedded in the LED structure, so no external controlled wire is accessible. Then I wondered if the headlight bulb included the controller, in which case my idea wouldn't work, no power lead to connect to.

Try getting to the bulb connector and seeing if there is full power when they are turned on. The number of wires would also be a clue, two for normal wiring and 3 or 4 for CANBUS. Also consider that a headlight bulb would draw something like 5 to 10 amps, depending on its power rating, so anything powering it would need to be pretty hefty, anyway.

Searching for CANBUS headlights it seems that only LEDs are CANBUS.

Try searching for the workshop manual, for your car and the schematics may provide enlightenment.




More thoughts, after re-reading your post.

The vehicle is still negative earth, the CANBUS is a two wire serial comms protocol. Loads are still required to have a power source, 12V, and a ground. The CANBUS provides an instruction to turn on or off. I doubt that the ECU would directly provide power for the headlights, and if it does it should be able to handle a low current relay, as well.

Maybe using a transistor, like a BD 139, to turn the relay on, would prevent any extra load on the ECU.

A revised circuit is attached. The diode is to prevent a voltage spike, when the relay is turned off. Parts are available from JAYCAR, including the relay.



Spot light.jpg

Edited by ozieagle
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