Thread: Help with electrics

Paul,

AFAIK the dimmer fuse only looks after the dimmer switch.
That means it can only be the dimmer switch itself shorting to earth (they are know to be unreliable after time)
To check for a short connect a 12v bulb in place of the fuse. If it lights then there is a short to earth in the switch
Phil.

Originally Posted by Phil B

Paul,

AFAIK the dimmer fuse only looks after the dimmer switch.
That means it can only be the dimmer switch itself shorting to earth (they are know to be unreliable after time)
To check for a short connect a 12v bulb in place of the fuse. If it lights then there is a short to earth in the switch
Phil.

Thanks Phil. Looks like it's the switch. Next problem where can I get my hands on one, in NZ.

The fault could be anywhere from the fuse to the instrument bulbs, it could be worn through insulation on the cables, a bullet plug that hasn't been pushed all the way in and so has some conductor showing, a bulb holder that has been deformed so the positive hits the negative - a thousand things really. It really pays to learn how to use a multimeter.

If you want to check it's not the dimmer switch, just pull the two cables out of the back of it and attach them together. The circuit will work just fine without it in there, you just won't be able to dim the lights (they'll be full brightness). The dimmer switches at ~25 years old are really more trouble than they're worth.

Bring it over if you want and we can have a crack at it, do your fuses at the same time, and figure out why my tail lights don't work when my headlights are on.

Originally Posted by BadCo.

Bring it over if you want and we can have a crack at it, do your fuses at the same time, and figure out why my tail lights don't work when my headlights are on.

Is it just your tail lights, or are the side lights at the front going out too? Uncommon to lose one without the other. If so, it's the little brass plate in the switch not balancing properly.

Originally Posted by Dervish

Is it just your tail lights, or are the side lights at the front going out too? Uncommon to lose one without the other. If so, it's the little brass plate in the switch not balancing properly.

Oh its also the side lights at the front, hadn't noticed. Aaaand the dash light goes out too when going from park lights to headlights.

So you reckon its this brass plate thing? Might have to take it apart and give it a clean out then, cheers for that Dervish!

Originally Posted by BadCo.

Oh its also the side lights at the front, hadn't noticed. Aaaand the dash light goes out too when going from park lights to headlights.

So you reckon its this brass plate thing? Might have to take it apart and give it a clean out then, cheers for that Dervish!

Yep, the dash light is on that same contact.

Ok, so inside the switch is a plastic plate with 6 copper studs through it. Power flows from two of the three studs at the rear to the studs at the front. At the headlights on position, the copper contact that connects the rear studs with the front has to balance on four studs and make contact with (at least) the right three of the four. A bad design, but so far so good. What happens though is that the bad contact with the studs makes them heat up so that the plastic plate melts and the contact recedes into it, making balancing on that contact and the other - non-melted or not as melted - contact impossible.

Have a look, you'll see what I mean. I fixed mine a few times by either bending the sprung loaded switch contact to match the stud profile or filing the studs so they were level.

Here's a photo from when I gave up and replaced mine with something else. Note the melted plastic plate with the copper studs sinking in.

What did you replace yours with? If mine is buggered would I be better of incorporating the switches into a raptor dash pod or something similar?