Driving lights staying on ???????????

Submitted: Wednesday, Apr 01, 2009 at 20:33
ThreadID: 67425 Views:4286 Replies:10 FollowUps:12
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Hello everyone,
Got a problem with my light force 170s, they stay on all the time. Checked connections and replaced most as they were abit average. Checked earth connections etc. They are connected to the high beam wire and also have an on/off switch on the dash. Even with the lights turned off they stay on. Any ideas would be appreciated.
Thanks in advance

Josh
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Reply By: kidsolo - Wednesday, Apr 01, 2009 at 20:43

Wednesday, Apr 01, 2009 at 20:43
sounds like the relay contacts are fused together
AnswerID: 357540

Reply By: oldpop - Wednesday, Apr 01, 2009 at 20:44

Wednesday, Apr 01, 2009 at 20:44
Josh
Sounds like you have faulty relay contacts in side fused together

regards
Oldpop
AnswerID: 357541

Reply By: Member - Murray R (VIC) - Wednesday, Apr 01, 2009 at 20:53

Wednesday, Apr 01, 2009 at 20:53
Josh sounds possibly like the relay contacts have stuck together, pull switch wire off relay, if lights go off its a switch wiring problem, if not pull battery wire off relay. If lights go off you have a faulty relay. Hope this might help.

Murray
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AnswerID: 357545

Reply By: Member - Tony V (NSW) - Wednesday, Apr 01, 2009 at 21:32

Wednesday, Apr 01, 2009 at 21:32
Sounds like your relay is sticking on, which is why the switch and the car headlight switch make no difference.
Possibly water or dust, or both got into the relay and caused arcing and the contacts welded together.

My 2 cents
AnswerID: 357562

Reply By: OzTroopy - Wednesday, Apr 01, 2009 at 22:07

Wednesday, Apr 01, 2009 at 22:07
Good Grief .....

A thread where everybody agrees ..... LOLOLOL

Diagnosis from this side of the keyboard ..... Relay.

Just check that the relay is of sufficient capacity to run the lights with a bit of reserve.

2 x 100w Lights draining almost 20amp through a 20amp relay will normally wear out contacts quicker than if using a 30amp capacity relay.
AnswerID: 357569

Reply By: MEMBER - Darian (SA) - Wednesday, Apr 01, 2009 at 22:24

Wednesday, Apr 01, 2009 at 22:24
Yep - and most relays are made to point down, and live in a dry place, cos they don't like water in them (you guessed it - I've been there :-o).
AnswerID: 357571

Reply By: Member - Roachie (SA) - Wednesday, Apr 01, 2009 at 22:43

Wednesday, Apr 01, 2009 at 22:43
Yeh, that reminds me I have to get a new "New Era" twin relay too. I have 4 x Lightforce 170s mounted at the back of my dual cab (facing forwards). I have wired them to a New Era twin relay; it's a relay that has 2 separate outputs with separate switching capability (if needed). It's located high and dry in the cargo box, very close to the lights.

Occassionally, when I flick down to low beam, 2 of the damned lights will stay on!!!!. I have to get out, go to the passenger's side, lift the cargo gullwing door, give the relay a tap,tap and the lights go off. I might try an drill a small hole (1/16") and squirt a bit of WD40 or contact cleaner in there and see if that fixes it before I replace.......

Maybe you could try that too...... (but those single relays are cheap enough, so why not just replace it anyway?)

Roachie
AnswerID: 357573

Follow Up By: OzTroopy - Wednesday, Apr 01, 2009 at 22:56

Wednesday, Apr 01, 2009 at 22:56
Are you using the old style with the points contacts or the new ones with the blade fuses ????

Old ones regularly needed a points file stuck through them in damp conditions ......
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FollowupID: 625663

Follow Up By: Member - Roachie (SA) - Thursday, Apr 02, 2009 at 08:09

Thursday, Apr 02, 2009 at 08:09
Mine has 2 blade fuses; (both 20amp)
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Follow Up By: Geoff (Newcastle, NSW) - Thursday, Apr 02, 2009 at 12:17

Thursday, Apr 02, 2009 at 12:17
Now there's a name from the past "New Era"

I used them years ago on a couple of earlier landcruisers I owned.

They seem to develop that problem over time were one, the other or both relays stick.

I went away from them for that reason.

I think what happens is they metal core of the relay coil is closer to a mild steel than the high silicone steel generally found in motors, contactors, relays and transformers.

Over time the core appears to me to become a permanent magnet of just sufficient strength to hold the relay closed without power on the coil.

If my theory is correct Bill you could recover the relay by running it with the switching wires reversed in polarity for a while.

Hang on, that may be difficult as I just remembered the New Era uses the case as the negative. It still could be done but it's not a matter of just swapping a couple of wires.

Geoff
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Follow Up By: Member - Roachie (SA) - Thursday, Apr 02, 2009 at 18:54

Thursday, Apr 02, 2009 at 18:54
Thanks Geoff.....I "think" you might be referring to the older style "New Era" jobbies. The current batch aren't earthed through the shell/body/mount, but I have never dismantled one to see what state the contacts are in.

I guess I may have to replace it with 2 separate Bosch or similar type single relays.

Cheers mate

Roachie
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FollowupID: 625820

Follow Up By: Geoff (Newcastle, NSW) - Thursday, Apr 02, 2009 at 19:38

Thursday, Apr 02, 2009 at 19:38
Hi Bill,

As I said earlier, I went away from the New Era's for the exact reason you are describing.

But if they've redesigned them so that you can reverse the polarity of the coils I'd give it a go!

You've got nothing to lose and it's a heap cheaper than buying new relays!

Looks like I need to revisit the New Era's as that was my biggest problem with them, apart from that I thought they were reliable and very well made.

Geoff

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Reply By: Member - Matt H (SA) - Wednesday, Apr 01, 2009 at 22:51

Wednesday, Apr 01, 2009 at 22:51
Josh,

Concur with everyone. That said, if the relay has "welded" itself shut perhaps the fuse you are using is of a too higher amperage.

So instead of blowing a fuse first, it has welded your relay shut.

A possible cause of this could be a bad connection (read; a short cct) that causes excess amps to travel through the relay.

A quick trip a auto electrician will confirm.

Matt
AnswerID: 357577

Follow Up By: Member - Mike DID - Thursday, Apr 02, 2009 at 10:15

Thursday, Apr 02, 2009 at 10:15
Why would fuse rating have any impact ?

The fuse has to be rated to take the continuous current - when the contacts weld shut, the current drawn is exactly the same as when the relay is switched on normally.
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FollowupID: 625723

Follow Up By: Member - Matt H (SA) - Thursday, Apr 02, 2009 at 21:39

Thursday, Apr 02, 2009 at 21:39
Hi Mike R,

Simple. The fuse fitted may be rated a bit higher than recommended. Excess current *could* conceivably "weld" the relay contacts shut but not necessarily blow the fuse straight away. Hence the lights stay on, because the switching cct of the relay is ineffective as the contacts are already stuck together keeping the lights on..

Hypothetically, if you had a relay designed to handle a continuous load of 25 Amps, but had it in a cct with a 35 Amp fuse, what would give out first? I'd suggest the relay contacts would. It could possibly weld the contacts shut but not actually self destruct in the short term. Given that the contact area of a relay is likely to be tinned, it will melt long before the copper it is attached to - and weld themselves together.

Fuses by nature are designed to blow very quickly and save the cct their installed to to protect from damage. On the other hand, a relay is designed to handle large currents (within their design limits), and are usually over slightly engineered to handle a current above what their ultimately advertised to handle. Therefore, they might not self destruct straight away. But if the wrong fuse of a higher rating is placed in the cct, the relay *could* become
the "weak link".

Fuses are by default, designed to be the weakest link in the chain. They are designed to blow (go open cct) before anything else in the cct is affected. But if a fuse of an excessively high amperage is fitted to a cct not designed for it - all bets are off.

Apologies if I have over simplified for you, but this but an option for Josh to look at.

Cheers, Matt
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FollowupID: 625846

Follow Up By: Member - Mike DID - Thursday, Apr 02, 2009 at 22:01

Thursday, Apr 02, 2009 at 22:01
. . . so if a fuse had blown, he should have taken it as a warning to put in a higher rated relay ????
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FollowupID: 625855

Follow Up By: Member - Matt H (SA) - Thursday, Apr 02, 2009 at 22:53

Thursday, Apr 02, 2009 at 22:53
Mike R,

Higher rated relay? No, (and my name is Matt by the way),

Given your detailed responses elsewhere in this thread, you know what I'm about to say.....................

A typical spotlight relay is 25 Amps. A pair of 100 Watt driving lights are ~ 16 Amps.

I'd be looking at why the relay welded itself together. And that in itself is hypothetical until such times Josh informs us otherwise.

But simple logic dictates (at least, in the world I live in), you'd check the fuse first (and if I saw something bigger than 25 Amp I'd be concerned), then the relay, then the lights (and associated wiring), and all earthing points including the battery and lights themselves.

Hey, I'm probably wrong, but it's all part of fault finding - and the idea of that is to systematically eliminate components of the cct until you isolate the culprit. Yes?

Matt.
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FollowupID: 625868

Reply By: Member - Josh (VIC) - Thursday, Apr 02, 2009 at 07:42

Thursday, Apr 02, 2009 at 07:42
Thanks everyone,
With all the different advice I'm now confused LOL. Think I will replace the relay. It was replaced only a couple of months back so kinda thought it should be okay. I did try a different relay but it was an older one so may have been faulty, may have been the one I replaced couple of months backLOL.
Thanks for your help.

Josh
AnswerID: 357605

Follow Up By: MEMBER - Darian (SA) - Thursday, Apr 02, 2009 at 14:08

Thursday, Apr 02, 2009 at 14:08
Yep - reminds me - just bought a relay the other week to get some air horns going that I've had for years - surprisingly cheap for what they do - 30A about $14 I think.
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FollowupID: 625772

Follow Up By: Member - Mike DID - Thursday, Apr 02, 2009 at 22:05

Thursday, Apr 02, 2009 at 22:05
Jaycar sell a 150 amp relay for $19.

http://www.jaycar.com.au/productView.asp?ID=SY4073

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FollowupID: 625857

Reply By: Member - Mike DID - Thursday, Apr 02, 2009 at 10:21

Thursday, Apr 02, 2009 at 10:21
For fraction of a second, lights will usually draw TEN TIMES their normal running current when first switched on.

This is because a cold filament has much lower resistance when cold than when white-hot - you can confirm this with a Multimeter.

So two 100watt lights will draw 160 amps initially - this is what can weld the relay contacts together.

If you have an inductive load like a relay or a motor, you get massive arcing when you switch the load OFF, due to collapse of the magnetic field, causing a high voltage spike of several hundred volts. This can also cause burning and welding of the contacts. This is the main reason 42volt car electrics failed to happen - too much arcing of contacts for a DC circuit.
AnswerID: 357631

Follow Up By: Mrbrush - Thursday, Apr 02, 2009 at 21:53

Thursday, Apr 02, 2009 at 21:53
My Driving lights seem to flash on for a second when I turn on the headlights everytime ?
this is happening with a brand new twin blade fused New Era Relay.
What the ?????
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FollowupID: 625853

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