electronic knowledge wanted in here please

steptoe · Post by **steptoe** » Tue May 12, 2009 1:51 pm

Thanks fer lookin' in.

I have a problem with a relay getting 1.3 volts when it should have nothing , or so I thought.the low voltage is in the low beam circuit when lights are on high beam. Problem is the 1.3 volts is pulling relay open.Dr light relay attempt for an L series. There is eart switch and pos switch wires at the headlight so 85 goes to earth , 86 goes to high beam circuit pos

Is there an electronic component that can prevent any power getting through to the relay trigger 86 unless I have 10 - 12 volts. capacitor? size or part number from jaycar cat.?

ta

Jonno

Gannon · Post by **Gannon** » Tue May 12, 2009 4:36 pm

Put 2 diodes in series with the relay coil (each diode has a voltage drop of 0.6v and 2 of them should block any voltage up to 1.6v)

But im curious why your getting 1.3v

Can you post a diagram of how its wired?

steptoe · Post by **steptoe** » Wed May 13, 2009 12:45 am

lights are as came from factory.

I am using LHS headlight as it is close to battery.
The dr light relay gets fused battery power to 30
both dr lights bulb gets the terminal 87
both dr lights earth gets earthed at captive nut in rad panel each side
LHS bulb the inner wire RW is earth switched so it goes to 85
the top wire RB is high beam power goes to 86

I only find 12v test tools - my buzzer and test light do not respond with the 1.3volts, however multi meter finds it!

My other post re how wire driving lights - Xtreme says not to use body earth in testing. This do not unnerstand.

Can you speak electrical rather than electronic please re where one end of one diode should go and where the other end of the other?

saying between 85 and 86?

Gannon if your ezemail or exemail did not boomarang I'd try email you a diagram.

steptoe · Post by **steptoe** » Wed May 13, 2009 1:09 am

'in series' , I understand (at 1.00am) and that will be in line from my 86 wire from the high beam headlight trigger. Someone the the12volt forum suggested same or a bosch style relay as they need 9v to pull. I have one 40A snafled from a Ford and a new tyco brand, they also work on 1.3 volts !!

Gannon · Post by **Gannon** » Wed May 13, 2009 5:33 pm

steptoe wrote: Gannon if your ezemail or exemail did not boomarang I'd try email you a diagram.

Boomerang??? My ISP advised that the email server will be down for a few hours this week. Try sending it again.

Im still baffled why its pulling in your relay, they really shouldnt be that sensitive. I was under the impression that a 12v relay should pull it at approx 2/3 rated voltage, 8vdc and drop out at about 1/3 rated voltage, 4vdc.

You must have bad earth somewhere which is creating a voltage drop of 1.3v between the negative side of the lamp, and the negative terminal of the battery.

Are you headlights dim?

steptoe · Post by **steptoe** » Wed May 13, 2009 10:39 pm

the boomerang was a few weeks back

I was surprised too at how little voltage could do it and it was even there at all !!

headlights just typical, not yellow, why the need for dr lights, but seeing as though the EA82T has done a head gasket or cracked again ...aaaargghhhh no great rush now sob...sob....

SCOOBIDOO · Post by **SCOOBIDOO** » Thu May 14, 2009 7:17 pm

Send 85 to its own separate ground.

steptoe · Post by **steptoe** » Sun May 17, 2009 12:20 pm

on the whole scheme of things that just may work, never tried it at this stage of wiring

Phizinza · Post by **Phizinza** » Sun May 17, 2009 4:19 pm

I've had this problem and found the cause. Even though the diagrams I have do not have this, the high beam indicator light is wired between the low and high beam lights. This is where the 1. what ever volts come from. Simple fix, put a 100ohm resistor in parallel of the coil on the relay. This "absorbs" that extra power. So thats between pin 85 and 86.

steptoe · Post by **steptoe** » Tue May 19, 2009 9:38 am

Phiz ! That sort of info shared is GOLD!! The discovery and the fix.
So....diodes or resistor can solve this problem huh??

How many hours or years did this find take?

Phizinza · Post by **Phizinza** » Tue May 19, 2009 9:42 am

Resistor, don't use a diode. The ohms of it depends on what voltage you have there to "soak up".

About 3 hours with my dad looking, measuring, looking, looking, cutting, measuring, looking, etc...
We had already figured out the solution, but I was adamant on finding the problem...

http://offroadingsubarus.com/headlight_relaymod.html

steptoe · Post by **steptoe** » Tue May 19, 2009 8:44 pm

Uh oh ! I bought both, a pack of diodes 1000V 1A (cat ZR-1007) and a pack 100 Ohm 1W resistors. I added two diodes in series in the lead from high beam pos+ to pin 86 of relay. It did the job. Bit of a buzz adding an electronic component to an electrical application - never done that before!

Or did you mean don't fit a diode in the same place you said to place resistor? between 85 and 86

funny thing is that pin 86 has about 11 V with no wire connected or relay switched on with lights on low beam i think

Phizinza · Post by **Phizinza** » Wed May 20, 2009 10:47 am

You put the resistor in parallel with the relays coil. So the resistor goes between 85 and 86. Not in before the relay.

I could explain to you how the lighting system works but I'm terrible at explaining these things and its pretty weird and kinda complicated...

Anyhow, you have it working I guess so stick with that

steptoe · Post by **steptoe** » Wed May 20, 2009 12:16 pm

Yep. Thanks. Understood your first instruction of locating resistor. Agreed it is weird switching. It works.It is unfinished project finished. Feels good Now, for the engine pressurising cooling system.....