Need some help from one of you electrical engineer types

[Dangerous Dave]

I recently installed an HID kit that I bought from a company called DDM Tuning in my Scion xD. Nice kit, well made, very compact ballasts. Works great except for one quirk...the high beam indicator no longer works on the dash. The HID kit plugged into one headlight connector only (oem bulbs were dual filament H4s, same as the FJR). If I plug a bulb into the empty connector, the indicator works fine. So I'd like to find a resistor that I can plug into the empty connector to simulate the load of a bulb. Problem is, Radio Shack doesn't sell anything even remotely close to the specs of the H4 bulb. It's a 12v 55w bulb and the resistance across the filament is ~ 1.2 ohms. So...can any of you electrical whizz-bangers help me sort this out??

Tanks!

 

[mcatrophy]

QUOTE (Dangerous Dave @ Jul 8 2010, 03:21 AM) <{POST_SNAPBACK}>

I recently installed an HID kit that I bought from a company called DDM Tuning in my Scion xD. Nice kit, well made, very compact ballasts. Works great except for one quirk...the high beam indicator no longer works on the dash. The HID kit plugged into one headlight connector only (oem bulbs were dual filament H4s, same as the FJR). If I plug a bulb into the empty connector, the indicator works fine. So I'd like to find a resistor that I can plug into the empty connector to simulate the load of a bulb. Problem is, Radio Shack doesn't sell anything even remotely close to the specs of the H4 bulb. It's a 12v 55w bulb and the resistance across the filament is ~ 1.2 ohms. So...can any of you electrical whizz-bangers help me sort this out??

Tanks!

Might be worth replacing the headlight dipping relay, it sounds as though the contacts have sufficient corrosion that they don't like the low current of the indicator bulb (google "relay wetting current").

If you really want to go down the resistor route, reckon on requiring (say) 2 amps, 14 volts, so 7 ohms nominal (anything from 5 to 10 should work ok).

Remember it will dissipate a fair amount of heat, around 30 watts, so use a 50 watt resistor. It will need to be of a type that can be bolted to a piece of metal to take the heat away -



Hope that helps some.

 

[Dangerous Dave]

Might be worth replacing the headlight dipping relay, it sounds as though the contacts have sufficient corrosion that they don't like the low current of the indicator bulb (google "relay wetting current").

Well, the indicator is an LED on an IC board in an '08 car. I think logic control is the issue rather than corrosion.

If you really want to go down the resistor route, reckon on requiring (say) 2 amps, 14 volts, so 7 ohms nominal (anything from 5 to 10 should work ok).
Remember it will dissipate a fair amount of heat, around 30 watts, so use a 50 watt resistor. It will need to be of a type that can be bolted to a piece of metal to take the heat away -



Hope that helps some.

So I'm looking for a 50 watt 7 ohm (roughly) resistor with a built-in heat sink, yes?? Thanks for the help.

 

[Dangerous Dave]

So I'm looking for a 50 watt 7 ohm (roughly) resistor with a built-in heat sink, yes?? Thanks for the help.

Found this resistor. I'll shop around to see if I can find one cheaper. Thanks again.

 

[ionbeam]

Found this resistor. I'll shop around to see if I can find one cheaper. Thanks again.

That is a pretty good price, it's the shipping cost that makes it expensive.

 

[Zorlac]

Found this resistor. I'll shop around to see if I can find one cheaper. Thanks again.

That is a pretty good price, it's the shipping cost that makes it expensive.

No comment on the whole idea, eh? :blink:

 

[ionbeam]

Found this resistor. I'll shop around to see if I can find one cheaper. Thanks again.

That is a pretty good price, it's the shipping cost that makes it expensive.

No comment on the whole idea, eh? :blink:

The elegant solution vs functional solution is not in good balance, but it is a solution. The best way to simulate a headlight is to put a bulb in the open socket. A preferred way to increase current draw is to put a higher value resistor in parallel with the HID so that the resistor only has to waste a little extra current. I didn't comment about the ~7 Ω resistor because it is brute force functional. Being a car and not a motorcycle which has limited generator power makes a big difference.

 

[bramfrank]

If this is for an FJR then you don't need a load to make the high beam indicator work - at least not for a Gen-II (don't have a manual for a Gen-I, so while it is probably the same, I won;t go out on a limb quite that far).

Consider that the Hi-Low switch could be unplugged or you might have dislodged the connector on the relay or that the relay is defective . . .

The high beam indicator is wired in parallel to the headlight high beam filaments - if the high beam is going on and the indicator is not, then check connectors, because a Gen-II uses a LED - Gen-I use light bulbs.

 

[Dangerous Dave]

Putting a bulb in the empty socket would work, but I don't think it would be a very good solution. A bulb wouldn't survive very long under those conditions. But a resistor will last forever. Problem solved, I think.

 

[ionbeam]

I didn't condone using a bulb; it is a perfect load but very unpractical too. I did say that a resistor is the preferred method.

I believe that putting a resistor across the open socket is tantamount to putting the resistor in parallel with the HID. If this is the case the resistor value can be significantly higher, reducing waste heat, allowing a physically smaller resistor and makes heat-sinking less critical.

Do you know the operating current of the HID kit? If yo do then we should be able to calculate a new resistor value.

 

[mcatrophy]

So I'm looking for a 50 watt 7 ohm (roughly) resistor with a built-in heat sink, yes?? Thanks for the help.

Found this resistor. I'll shop around to see if I can find one cheaper. Thanks again.

The resistor would be fine, but must be bolted to metal to take the heat away; the metal body only transfers heat to the mounting metal, not enough directly to the air.

POWER RATINGVishay RH resistor wattage ratings are based on mounting to the following heat sink:

...

RH-50: 12" x 12" x 0.059" thick aluminium panel (291 sq. in. surface area)

I'm not sure I understand what you are doing exactly. Does the HID take its power from one of the headlamp sockets, or is that used to switch a relay? In either case, if the HID works correctly, the indicator should as well.

If the HID is driven by a relay that is energised from the dip (or dimmer) switch directly, then my "wetting current" issue holds, and a new relay would be the better option. No heat to dissipate, no extra load on the generator.

 

[Dangerous Dave]

I'm not sure I understand what you are doing exactly. Does the HID take its power from one of the headlamp sockets, or is that used to switch a relay? In either case, if the HID works correctly, the indicator should as well.
If the HID is driven by a relay that is energised from the dip (or dimmer) switch directly, then my "wetting current" issue holds, and a new relay would be the better option. No heat to dissipate, no extra load on the generator.

The HID "kit" takes its signal from one of the headlight sockets. There is an external power source to the HID kit from the battery and there are also external grounds to both HID bulbs, and the high beam signal actually powers a solenoid in each bulb to change the depth of the bulb in the housing for high/low beam. Apparently the solenoids don't draw as much current as the original high beam filaments. Bolting the resistor to the body for heat dissipation should not be a problem as it appears to have fairly long leads. Additional current draw should also not be an issue since it's a car...not an FJR. I found those same resistors on Fleabay for a fraction of the price shipped. Probably go that route. The kit is mostly plug and play, so sticking a resistor in the empty headlight socket seems like a more attractive option than splicing a resistor into the HID kit harness. Two spade terminals, two screws, and I'm done. I can live with that. I'll let you all know how it pans out.

 

[mcatrophy]

... it's a car...not an FJR. ...

I hadn't appreciated it isn't an FJR (I've never heard of a "Scion xD", and we're in the "FJR Motorcycle Forums" area).

So, I googled "Scion xD main beam indicator" and got this as the first hit. Seems to be an easy fix. (You may need to read several posts to get the correct information.)

 

[Dangerous Dave]

I hadn't appreciated it isn't an FJR (I've never heard of a "Scion xD", and we're in the "FJR Motorcycle Forums" area).

Guilty as charged (pun intended), but I know that the people most likely to be able to help me solve this problem (like Alan and yourself) like to hang out here. Not sure if you get the Scion xD on your side of the pond or what it's called there if you do. It's my new "work car" I just picked up now that my daughter just finished her Chemical Engineering degree and I'm done paying tuition. :yahoo: A graduation present to myself if you will. Here's a pic of it.

So, I googled "Scion xD main beam indicator" and got this as the first hit. Seems to be an easy fix. (You may need to read several posts to get the correct information.)

Excellent find! Thankyou!! I had to study the schematic for awhile to make sure there would be no other ill-affects. He's basically just jumping 12v to the high beam LED and the headlight relay, both of which only get ground when the dimmer switch is in the high beam position. I would post up the schematic for your review, but just can't seem to get a pdf up here. :blink:

I'll go to Radio Shack when they open and pick up a resistor...or in all likelihood, I'll be forced to buy a pack of 20 for $1. I should have the final answer this afternoon. Thanks again for the help guys.

 

[ionbeam]

10K @ 12 volts = 0.014 watts -- 1/4 watt is 0.250 so the 10K in a 1/4 watt size should be just fine.

 

[Dangerous Dave]

10K @ 12 volts = 0.014 watts -- 1/4 watt is 0.250 so the 10K in a 1/4 watt size should be just fine.

Hmmmm, not quite getting the desired results. When I put in a 10k 1/4 watt, the high beam indicator doesn't come on. When I stick in a 1 ohm 10 watt resistor I had laying around, the indicator comes on, but the resistor gets REALLY hot, REALLY fast! Thoughts??

 

[mcatrophy]

...Excellent find! Thankyou!!

...

I would post up the schematic for your review

...

That's why we're here, and yes, I'd seen the diagram.

10K @ 12 volts = 0.014 watts -- 1/4 watt is 0.250 so the 10K in a 1/4 watt size should be just fine....

Good call for doing the sum. I'd not thought to do it, sorry. [geek] It was obvious to me without (well, I have been designing electronic circuits professionally for over 46 years and quite a few hobbying years before that) :crazy: [/geek].

And, pedant as I am, to be safe, use 14.5 volts, so .021 watts. Still a 1/4 watt reistor. :innocent:

 

[Dangerous Dave]

And, pedant as I am, to be safe, use 14.5 volts, so .021 watts. Still a 1/4 watt reistor. :innocent:

Unfortunately that doesn't work.

Hmmmm, not quite getting the desired results. When I put in a 10k 1/4 watt, the high beam indicator doesn't come on. When I stick in a 1 ohm 10 watt resistor I had laying around, the indicator comes on, but the resistor gets REALLY hot, REALLY fast! Thoughts??

 

[Constant Mesh]

Don't know if a Scion xB is similar to yours.

Here's its headlight schematic.

https://scionlife.org/Scion_Docs/2006_xB_Wi...20headlight.pdf

Looks like the lamp power enters the common between the high and low beam filaments. The dimmer switch completes the circuit to ground for either the high or low beams. From this drawing I don't see how the lamps can affect the high beam indicator on the instrument cluster.