wiring geeks check my schematics please!

[_ethrty-Andy_ 2122]

Im going to wire up some auxiliary spotlights on my old mans late model Hiace tomorrow. They are dual 100W spots.

His requirements are,

• they are switched, so he can use the factory high beams without the auxiliary lights coming on, i.e. as per factory for urban driving
• 
  
• when they are switched on, they can be killed by both the factory high beam stalk and the toggle switch
• 
  

I can up this schematic after a few days thinking about it:

Please comment or criticise, let me know if your not happy with that!

[Haitoman 110]

That will work fine. I would use a lesser rated fuses however to reduce the possibility of a fire if something goes wrong. You won't need more than 2A for the relay and 10A (100/13.8 = 7.2A) for the spots. Make sure you use a 'slow blow' 2A as the relay in-rush current may be quite high.

[_ethrty-Andy_ 2122]

do you think this circuit setup will dim the stock high beam headlights at all or excessively?

my first idea was good, but then i realised it would probably make the stock high beams them very dim or turn off maybe, so came up with the solution above instead

[gjm 3208]

To some extent, it depends on the alternator output. I ran 4x150W KC Daylighters on a Land Rover without problem, but that had a big alternator and significantly more (potential) output than standard. (The whole vehicle had been rewired, too.)

[Haitoman 110]

do you think this circuit setup will dim the stock high beam headlights at all or excessively?

my first idea was good, but then i realised it would probably make the stock high beams them very dim or turn off maybe, so came up with the solution above instead

You don't have a choice unless you power the spotlights from a separate battery. As gjm said, it depends on what your alternator is rated and the condition of earths and other wiring. When you start playing with high current i2r losses become significant.

[kiwi535 538]

get another relay and run the high beam headlights straight of the battery too(and another for the low beams if you feeling up to it),will probably increase output just doing that

[Allanw 1053]

Mount the relay out by the lights (One GOOD relay would be fine for both lights), tap into the wire for one of the factory highs to feed through a fuse then direct to the relay coil, and then instead of earthing the other side of the relay coil, run the earth back to the new switch and just use the switch to earth the relay coil - less wiring, and certainly less live wiring runs - you can connect the other side of the switch to an earth under the dash, instead of having the live from the high beam running all the way to the switch and back. There's very little load on the feed, and it saved having to run a power wire all the way to the dash and back to the relays.

The only real difference with a separate feed for each aux light, is if a fuse blows, both aux lights will go out on a single feed. Not really that major. However, fitting two relays isn't much more work.

I'd certainly move that Aux switch to the other side of the relays (earth side).

[hotwire 352]

Yep ^^^^^^ what he said. I too would only use one relay - a 40 amp one & run the switch wire as prescribed above.

One thing to note though, I cant remember if the late Hiace's run conventional lighting circuit or insulated return as in the earlier models.

If insulated return, to confuse things - you will need to tap the relay wire into the low beam wire to get the relay to operate on high beam.

You can tell if insulated return system by confirming if one or two lamp terminals are live at one time. this system powers the filament common & earths either low or high beam through the dip switch. Means what ever filament is not on - the other will be sitting at open circuit - 12v, this is enough to power the relay.

[_ethrty-Andy_ 2122]

I'd certainly move that Aux switch to the other side of the relays (earth side).

Great thinking, will do!

Yep ^^^^^^ what he said. I too would only use one relay - a 40 amp one & run the switch wire as prescribed above.

One thing to note though, I cant remember if the late Hiace's run conventional lighting circuit or insulated return as in the earlier models.

If insulated return, to confuse things - you will need to tap the relay wire into the low beam wire to get the relay to operate on high beam.

You can tell if insulated return system by confirming if one or two lamp terminals are live at one time. this system powers the filament common & earths either low or high beam through the dip switch. Means what ever filament is not on - the other will be sitting at open circuit - 12v, this is enough to power the relay.

I guess I will find out when I'm in there. I want to run them off two separate relays for reliability reasons mainly.

but if it causes more headache than its worth i may do just one relay, see how I go. I would put the lights in parallel is that right?

Cool, so in other words, you are saying the factory switch is likely to be on the earth side of the factory light?

[_ethrty-Andy_ 2122]

well thanks for your help guys! Long story short, it works perfectly as per the brief.

For those that are interested, the 12V into the stock high beams was switched, and both high and low had the common ground, so that made it nice and easy for wiring up the coil side of the relay. took it from that 12V, into one side of the relay, then on the 0V side to ground via a switch to a factory ground point under the dash as per Allans recommendation. on the switch side of the relay, took it from the battery via a fuse as close to battery as possible, and out to the relay (which had another built in fuse, but was too far from the battery for my liking, thats why i put another one up close to the battery), and then the other side of the relay to the lights, which turns out they ground through the mounting brackets. i ended up using one relay to power both lamps, so we will see if they are bright enough, may try two relays if he is not happy with the result output.

Initially thought i had mucked it up, but turns out one of the bulbs had a 24V bulb in it (was fitted to a truck before), and the other one had a bad ground contact, so when i had "finished" one was very dim and one not on at all. so fixed both of them and look quite cool, was way too early before night fall so i havens seen them at night yet, but looking forward to that.

[hotwire 352]

Yep, I knew that Toyota had changed to conventional wiring setup for headlights, just couldn't remember when. Than ran insulated return system on most of their vehicles for years. One/two relays won't change the lamp brightness, it is just a matter of the relay contacts being able to handle the current flowing through them.

[_ethrty-Andy_ 2122]

Yep, I knew that Toyota had changed to conventional wiring setup for headlights, just couldn't remember when. Than ran insulated return system on most of their vehicles for years. One/two relays won't change the lamp brightness, it is just a matter of the relay contacts being able to handle the current flowing through them.

His Hiace is MY2009 so must be before that. my own Hiace is a 1994 and the earlier shape, don't know what the setup is in that (don't fix what aint broke etc)