Negative Switching Headlights?

Hi Guys

My son brought a 2006 Toyota Hilux Ute (that was the first problem) and then he wants to install two spotlights (second problem) because the wiring is negative switched which has me buggered, so after explaining the facts of life to him for buying a Toyota he said it was all my fault because i would not sell him my TDi42....?
Anyway after trawling the internet trying to find out how to do it right(to many conflicting idea's) i came upon this two solutions

Option 1.
Relay ports:
30 > Battery +
86 > Battery +
87 > Spotties (i assume the positive)
85 > Rear of headlight, red wire with yellow stripe. (yep i found that one)

Option2.
Toyota headlights are switched negative.
3 wires - 12v+, low beam, high beam

with head lights off you will meter 12v to ground on all wires
with low beams on the wire that meters 0v to ground is the low beam switch
with high beams on 2 wires will meter 0v to ground
the high beam wire will have 12v on low beam & 0v on high beam
wire your spot light relay from battery positive, through the dash switch, through the relay and onto the high beam wire.

I was hoping an electrical guru here can confirm if either of these are good to go or do i go back to searching the internet.
Now i know why i got a Nissan :))

send yendor a pm he's the man

Hi Mojo,

Your second option will work as long as the vehicle does't have HID headlights fitted.

The 12 volts that switches on with high beam on at the back of the headlight plug is actually the low beam circuit. This is how negatively switched lights work. This doesn't matter you can still use this feed for your spot lights.

So find this wire. It should be the wire going to the only horizontal pin in the back of the headlight plug. Join your wire to it and connect the other end to your spotlight switch in the dash.

Other end of spotlight switch goes to 85 terminal of the relay.

Pin 86 of the relay connects to earth.

Pin 30 of the relay connects to battery positive via a suitable fuse.

Pin 87 of the relay connects to the positive of your spotlights. Don't forget to connected the negative of your spotlights to earth.

There is another way to wire the spotlight relay using the negative switching but the above will work fine.

Cheers Rodney

Thank you very much for that Yendor that solves my problem, i am assuming they are standard halogen headlights but as he only got it recently i will check them first, i know he has 2 sets of spotlights 1 LED and 1 Halogen is that diagram good for both or will the LED be a problem.
You say there is another way to wire them as well? makes you wonder why they would make it so complicated.
Anyway cheers for the help, i will make a start on them when the weather cools down a bit, had 3 days of 45 so far...not doing anything in that temp except hibernate.

Regards
Mojo

Hi Yendor

Decided to work at night as it is cooler, fitted the LED spotties wired up as per your instructions and away they went first time, no smoke no flames no problems so i must have got it right.
I reckon you deserve a six pack for that help, but as you are not here i will personally make sure they don't go to waste.
I will file those instructions away for next time some idiot buys a Toyota and wants to fit spotlights....

Cheers mate and thank you.
Mojo.

Glad to hear you got it sorted. I'm sure the beers went down real nice.

He can run what ever type of driving light he wants to via the relay. It will work fine.

He will only run into problems if he fits HIDs or LEDs in the headlights.

Hi Yendor

I didn't realize you were so thirsty, those first 6 didn't even touch the sides.
I tested the spotlights and they worked fine on high beam and went off on low beam as normal so i left it at that.
My son's girlfriend was checking things out as she brought a new sound system for the car and discovered that she could switch the spotlights on with no headlights running, low or high beam, nothing (yes she is blonde).
So i thought i better check to make sure she wasn't having a dizzy spell, and she was right the spotties came on when she hit the switch and no other lights were on.
I assume that has nothing to do with negative switching or does it, and how do i get rid of it.

Cheers mate

Mojo

I'm always thirsty lol.

What happens if you turn the spot light switch off when high beam is on?

What type of spot light switch did you use? Did you connect any other wires to the switch?

You did connect terminal 85 and 86 at the relay as I described?

Hi Yendor

If you turn the spotlight switch off when high beam is on the spotlight turns off as normal
The Spotlight switch is a Rocker type switch from Auto One and the only wire connected off it is the wire from the center terminal White/Black Stripe from the RHS Headlight 3 pin plug and it returns to terminal 85
Terminal 86 connects to earth
Terminal 30 connects to the + on Battery
Terminal 87 Connects to the + on the Spotlight and the Negative of the spotlight goes to Negative on the Battery.
The Spotlights are 120mm LED connected with Deutsch Connectors.
The 3 way plug wiring looks a bit shabby and looks like it had something connected at some stage then removed and taped up, but is is taped and not shorting out and probably needs replacing in the near future.
I will try and attach a wiring diagram of what i have done and i also have the Toyota wiring diagram out of the manual if you need it.

Attachment 64813

I will try again with my attachment

Here is the original wiring Diagram
Attachment 64814

Attachment 64815

Here is the original diagram

Yeah it's to do with the negative switching. You will need to change it to the second option I was talking about previously.

Disconnect the wire you connected to the black and white wire at the headlight plug and connect it to the black wire at the headlight plug (or the red wire if connecting to the LHS headlight).

Disconnect the earth wire at terminal 86 at the relay. Run a new wire from terminal 86 of the relay and connect it to the red and yellow wire at the back of the headlight plug.

The rest of the wiring is the same.

No worries mate i will try that and see what happens.
I believe negative switching was to prevent you from loosing both headlights if you get a problem with the system....i wonder if it is worth the trouble. lol

Your a Bloody legend Yendor, that did the trick and no surprises this time
Thanks for the help i would have been stuffed without it.....i think it's time to avoid Toyota wiring for a while
Cheers mate

Mojo

Negative switching is just another way of doing it. Instead of putting the switch in the positive side of the circuit the switch is fitted in the negative side. It just most people can understand what's happening better when it's positively switch.

All headlight circuits on all vehicles are set up so if a problem occurs the worst that should happen is you lose headlights on one side of the vehicle only. This is regardless of negative switching or positive switching.

Toyota have changed their headlight circuit over the years. They use to put a relay in the power supply going to the headlights. This relay would switch power off to the headlights when the lights were turned off. This relay now being missing is why you had the problem with being able to turn the spotlights on with the headlights off.

Can I ask where you got the wiring diagram from? Did you download it? I would like to get a copy if possible.

I must be one of the slow learners as well as it had me stuffed, but thanks for the help i needed it.
Check your PM
Mojo

Thanks for the PM it worked a treat.

Good stuff mate i am glad to be able to help someone else for a change

Hi, sorry to jump in so long after the party;)

, but I need help with a Toyota Corolla 2009 and a Whelen UHF2150A and you seem to know a little about Corolla.

I contacted Whelen to buy a UHF2150A, which is a wig wag for the headlights, but they told me it wouldn't work on my Corolla 2009.

The reason was that the lights were controlled by the computer and if you inserted this UHF2150A, it would give all kinds of error codes and just explode, at least, that's the impression he gave.

Is this at all correct and if so, why? Are there alternatives?

I also don't understand this, cause it's quite a simple circuit. See attached. Attachment 70561

Send Yendor a PM as he is the electrical guru i believe