Trailer lights issue

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Shifta
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Joined: Mon Aug 06, 2012 2:35 pm

Trailer lights issue

Post by Shifta »

Almost ready to have my home made trailer inspected for rego and the lights were all good but all of a sudden they’ve gone haywire. Here’s what they are doing:

1. With just Taillights on – work ok
2. Indicators on their own – work ok
3. Indicators on with the Taillights – Indicators and tail lights flash alternatively
4. Brake lights on their own – Brake lights work but both indicators have a slight glow
5. Brake lights plus right indicator – indicator stays on constant while the brake lights flash
6. Brake lights, indicators, and tail lights – Tail lights cut out, brake lights flash, and indicators have a slight glow.

Already replaced the plug, checked the car side and isolated each set of lights and all work fine in isolation. It’s only when I try to combine them that it all breaks down. Any ideas? I have a cheap multimeter but not really proficient in it. I've double checked all the wiring and also compared the plug set up to my other trailers and everything is fine up to the car/plug intersection.

Any tips on finding the cause? Thanks in advance :)
A112H
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Joined: Tue Mar 24, 2009 5:01 am

Re: Trailer lights issue

Post by A112H »

Sounds like you have commodore tail light wiring, lol

It sounds like an earth issue to me, maybe try a direct earth from the trailer side of the plug to a good earth point on the car.

Check this out, this is the universal 5 pin trailer loom set up.

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75wagon
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Re: Trailer lights issue

Post by 75wagon »

Yep, I'm with Jason, you have a bad earth or contact somewhere.
Go through and check all connections (that includes globes).

Dave...
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Shifta
Posts: 1191
Joined: Mon Aug 06, 2012 2:35 pm

Re: Trailer lights issue

Post by Shifta »

Cool, thanks guys. I'll try the manual earth lead idea tomorrow after work. The other strange thing I noticed is that the commo battery died pretty quick after testing every now and then. If there was a dodgey earth, would it draw more power from the cars battery?
geezer101
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Joined: Sat Jun 11, 2011 10:49 pm
Location: adelaide (SA)

Re: Trailer lights issue

Post by geezer101 »

You know how to use a hydrometer? If it's not a sealed type battery, this will give you a better indicator of how healthy your battery is (output voltage isn't always a good indicator).
Shifta
Posts: 1191
Joined: Mon Aug 06, 2012 2:35 pm

Re: Trailer lights issue

Post by Shifta »

Yeah I might need to suss that out with the battery! I went over the trailer tonight and mostly fixed the crazy flashing problems by running the Earth wire on the plug straight to the chasis but there is still a slight pulse through the tail lights when the indicators are on. The current tail lights look to be not earthed at all - the housings are plastic and there are only 3 wires going to the terminals - power for brakes, tail, and indicator lights. The only earth connections I found were from the number plate light to the chasis and the two guard lights I installed last week earth themselves onto the guards. I found the white earth wire down the back and it was cut off and not used - almost seems like power was running to all the globes and the tail lights were somehow piggy backing off the number light earth? I think it will be good enough for the inspection but I reckon I'll at least upgrade the light units pretty soon.
A112H
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Joined: Tue Mar 24, 2009 5:01 am

Re: Trailer lights issue

Post by A112H »

Glad you got a result mate. Supercheap do pretty cheap trailer lights with a direct earth into the loom, might be worth picking up a pair of those before the inspection and maybe 5m of trailer loom to re-wire
Shifta
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Joined: Mon Aug 06, 2012 2:35 pm

Re: Trailer lights issue

Post by Shifta »

Yeah I'll have another look tomorrow night and see how I go for time ( inspection is first thing wednesday morning ). After writing that it seemed strange so I just went back out the shed and checked those lights - I think the tail lights are kinda earthed, just not very well designed!
A112H
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Joined: Tue Mar 24, 2009 5:01 am

Re: Trailer lights issue

Post by A112H »

Yeah, there are some didge ones out there. I don't think any are as good as the old metal based lights used to be.
Shifta
Posts: 1191
Joined: Mon Aug 06, 2012 2:35 pm

Re: Trailer lights issue

Post by Shifta »

Quick update. Last night got home from work and thought I'd quickly go to the shops and suss out some lights. Turns out one of the workers at Sprints put a pile of LED lights in a $24.95 special bin by mistake. They weren't too happy about it but ended up getting a pair for $30 :). So was out in the shed last night riggin em up - turns out they needed custom brackets made which I didn't have time to do so rigged up a temporary setup and the lights were all fixed and working perfectly. Had trailer weighed this morning then straight round the Trailer place - the dude didn't even check the lights! Actually, he didn't check much at all. Complianced and rego'd - nice. I bought 10metres of trailer wire off him for $35 and will redo all the wiring over the weekend before bolting number plate on and waiting to use the thing. I figure I might as well do it properly. Stoked how it's all turned out :).
A112H
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Joined: Tue Mar 24, 2009 5:01 am

Re: Trailer lights issue

Post by A112H »

Nice one mate :thumpsup:
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