Speedhut High beam dash indicator

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heli006
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Speedhut High beam dash indicator

Post by heli006 » 15 Mar 2018 22:30

I’ve installed 7 gorgeous Speedhut gauges and the gps speedometer I ordered has signal indicators and a high beam indicator led. It’s a single blue wire intended to provide a 12 positive signal to the led when high beams are activated. But of course our Datsun have a switched ground headlight system and I can’t find a positive signal anywhere to correspond to high beam activation. I’ve checked the headlight switch, the high/low switch on the steering column, the headlight relay, and just about anything else headlight related on the wiring behind the dash. I’ll need a functioning high beam indicator to pass inspection. Anyone have any ideas? Id rather not get involved complicated relay install scenarios and end up with an ugly hack just to get a tiny led to illuminate....surely someone with a similar problem had encountered this before?

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zKars
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Re: Speedhut High beam dash indicator

Post by zKars » 16 Mar 2018 05:03

Ah yes. The old "wrong polarity" conundrum...

You need a relay. The ground signal from the high beam switch is used to turn the relay on, (any handy +12v on relay term 85, hi beam ground to term 86) which then connects that same handy +12v on term 30 to term 87, that is connected to that pesky LED.

Three B's Racing
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Re: Speedhut High beam dash indicator

Post by Three B's Racing » 16 Mar 2018 05:32

heli006 wrote:I’ve installed 7 gorgeous Speedhut gauges and the gps speedometer I ordered has signal indicators and a high beam indicator led. It’s a single blue wire intended to provide a 12 positive signal to the led when high beams are activated. But of course our Datsun have a switched ground headlight system and I can’t find a positive signal anywhere to correspond to high beam activation. I’ve checked the headlight switch, the high/low switch on the steering column, the headlight relay, and just about anything else headlight related on the wiring behind the dash. I’ll need a functioning high beam indicator to pass inspection. Anyone have any ideas? Id rather not get involved complicated relay install scenarios and end up with an ugly hack just to get a tiny led to illuminate....surely someone with a similar problem had encountered this before?

Couldn't you simply connect a led light to i believe it's #12 pin on the original instrument panels rear plug and mount it on your dash?
"Lastnight the wife said oh boy when your dead you can't take nothing with you but your soul oh "Think"
- John Lennon

heli006
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Re: Speedhut High beam dash indicator

Post by heli006 » 16 Mar 2018 08:28

I believe I tested all those wires on the round cannon plug that plugs into the stock instrument panel, the issue is that it’s a negative switching ground so there is no positive signal. Led’s Are polarity sensitive unlike regular incandescent bulbs

Three B's Racing
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Re: Speedhut High beam dash indicator

Post by Three B's Racing » 19 Mar 2018 05:17

heli006 wrote:I believe I tested all those wires on the round cannon plug that plugs into the stock instrument panel, the issue is that it’s a negative switching ground so there is no positive signal. Led’s Are polarity sensitive unlike regular incandescent bulbs
So why not use a regular incadescent bulb?
"Lastnight the wife said oh boy when your dead you can't take nothing with you but your soul oh "Think"
- John Lennon

heli006
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Re: Speedhut High beam dash indicator

Post by heli006 » 19 Mar 2018 05:49

Because the gauge has an led not an incandescent bulb

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zKars
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Re: Speedhut High beam dash indicator

Post by zKars » 19 Mar 2018 07:31

The LED's in the speedhut gauges are not accessible to either change to a different style of bulb nor change it's wiring around to switch it's polarity requirement. The use of a relay to do the polarity switch (see my post above) is the simplist way to accomplish this. If my description is insufficient, perhaps this diagram from Google will help.
CFAEC023-A068-4150-A912-50C2DC48DEEC-3998-000003FE82B5A128.gif
CFAEC023-A068-4150-A912-50C2DC48DEEC-3998-000003FE82B5A128.gif (4.02 KiB) Viewed 341 times
Of course it's the opposite of what you need (it creates a negative trigger from a positive input) but just reverse the ground and +12 at each terminal to get what you need

heli006
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Re: Speedhut High beam dash indicator

Post by heli006 » 19 Mar 2018 12:46

zKars wrote:Ah yes. The old "wrong polarity" conundrum...

You need a relay. The ground signal from the high beam switch is used to turn the relay on, (any handy +12v on relay term 85, hi beam ground to term 86) which then connects that same handy +12v on term 30 to term 87, that is connected to that pesky LED.
Awesome, I have one of those relays kicking around. I’ll see if that works for me.

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Re: Speedhut High beam dash indicator

Post by Three B's Racing » 20 Mar 2018 06:01

heli006 wrote:Because the gauge has an led not an incandescent bulb
Sorry, what I meant was why not use an incandesant bulb instead of the led within the gauge?
"Lastnight the wife said oh boy when your dead you can't take nothing with you but your soul oh "Think"
- John Lennon

heli006
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Re: Speedhut High beam dash indicator

Post by heli006 » 20 Mar 2018 07:20

There is no room, and disassembling the gauge under warranty would not be my choice. The high beam led is a tiny one, you can see them on speedhut a website. The solution is indeed to wire a relay up to give me the positive signal from the negative signal as a previous poster said. I looked it all up on YouTube and it’s actually pretty simple to do, so I’m glad there is a great solution. I’ll be doing it in the next day or so, and I’ll post the result. Relays are so versatile, I had no idea they could be wired to do so much.

heli006
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Re: Speedhut High beam dash indicator

Post by heli006 » 21 Mar 2018 20:32

It works! Wiring a 4 terminal relay to close with the ground signal from the dimmer, shuttling positive power through to the led.

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