[Clockberg]

Hey people.

So I just bought myself a 96' sierra coily in great condition. I'm stoked to get my hands on one at last. I don't know much about mechanics but am keen to learn and now have a car I care enough about to learn on.

Now, on to my first problem!

The lights work. High beam works both when I push it out or pull it in. The spotlights and parking lights work. Regular beam does not. I have talked with a friend who is no professional though much wiser then I and he said it could be the 'dimmer switch'. I thought I would come here for some advice before trying anything as said friend has never owned a Suzuki.

So if anyone has any insight, it would be greatly appreciated. Maybe a list of possible causes, how probable each are and how easy they would be to fix.

As aforementioned, I know next to nothing about the inner workings of a car or the complexity of this issue so let me know if this is something a bit too much for me to handle, as this will literally be my first venture into working on my own car.

Cheers
-Clockberg

[alien]

Dimmer switch is likely, i would assume given it's a sierra it will be straight forward to replace.

That said, i don't think i've ever seen one fail (at least on here) and a search of suzistore (www.4wdpartshop.com.au) doesn't seem to show a result. May be worth asking if they can source a replacement, even if it's from a wreck if new is too costly?

[fordem]

Before you go complicating things, try the simple fixes - are the headlights/bulbs good? You can either swap a known good one in, or verify with a test meter - the Sierra uses a double filament headlamp, one filament for high beam, one for low beam, and you can have one of the two go without affecting the other.

Next - Suzuki uses a "ground" or negative switched headlight circuit - +12V goes from the battery, through a couple of fuses to the headlamps - each headlamp has it's own fuse - and then the two high beam filaments are wired together and go to the "dimmer" switch, and the two low beam filaments do the same, the dimmer switch is then wired to the light switch and through it to ground.

I'm describing this circuit in detail because it confuses many people.

Look at the headlamp wiring - three wires - I believe white-with-red on one headlamp, and white-with-blue on the other - these two should have +12V at all times - each side will also have a red wire and a red-with-white wire - red is high beam, red-with-white is low beam - these should also have +12V when the lights are off, but should go to 0V when the ligts are switched on - the red wire will be at 0V when the high beams are on, at 12V when the high beams are off, the red-with-white will be at 12V when the low beams are on, at 12V when the low beams are off.

10 mins with a test meter should tell you if the problem is the lights or the switch/wiring.

[Clockberg]

Thanks for the replies.

Fordem, I did know about the filaments with a little research before this post. Because both the regular beams don't work it led me to think it wasn' that. Though what do I know! I will borrow a friends multimeter this weekend and go through the tests that you explained and after that will move on to dimmer switch if need be.

The car has never had any mods or anything after market so the wiring definitely hasnt been mucked around with.

I came across a part online that was the a whole piece. Indicators wipers and lights in one piece. Would the dimmer switch be a part of that?

[fordem]

I've known folks drive night after night with one low beam headlight out and not know it was out, but trust me, if the second one went out, they would know. Now, this is a "new-to-you" vehicle, are you sure the previous owner would have known or cared?

Regarding the switch, yes, I believe on that vehicle, a single unit handles turn signals & lights.

[Gwagensteve]

Combination switch failure is most commonly associated with running high wattage globes on a standard loom. Sierras don't have relays on their headlight circuit - all current flows through the combination switch.

[BlueSuzy]

fordem wrote:

I've known folks drive night after night with one low beam headlight out and not know it was out, but trust me, if the second one went out, they would know. Now, this is a "new-to-you" vehicle, are you sure the previous owner would have known or cared?

This has happened to my wifes Corolla. She uses headlights on at daytime, High fog area in winter. She rarely drove at night so never realised they were both out until she had to drive at night one time.. It was the bulbs. High beam worked but the lowbeam were blown. Individual bulbs but would be same with dual filament H4/sealed etc

[Clockberg]

Just to clear it up, is the switch to the right of the steering wheel factory? The switch activates the 'fog lights', a setting brighter then high beam.

It isnt the bulbs. Ill try do the multi-meter test when I can get my hands on one.

[Clockberg]

So I think the low beams are wired to the highbeam switch and the highbeams are wired too the toggle switch on the dash. Not sure why. I'd like to wire the low beams and the high beams back to the regular factory spot and wire a lightbar to the toggle switch on the dash.

Looking under the dash and seeing the huge amount of wires going every which way is quite intimidating. Ive never done a single thing to do with electronics ever, auto or not. Is this something that is do-able with absolute entry level skill? Or should I just hire an auto-electrician to do it for me and practice later on with something simpler?

-Cheers

[fordem]

It's starting to sound like someone has been fiddling in your wiring - the norm is a rotary switch on the end of the turn signal stalk - off is all the way "top-to-you" - first click "top-away-from-you" is park lights, second click is park + headlights. Pull the stalk towards the wheel to flash, push away from steering wheel for high beam, center position is low beam.

If you have NO electrical experience whatsoever, either take it to an electrician or find a friend to help you.