My formal intro and newbie question about dash/tail lights not working..

ghostintheshell · Jul 22, 2015

Hey guys!
My name is Alex, I'm new to the forum (well as a poster at least, I read the forum all the time), sorry if this is not the way or the correct forum to start a thread as a new member, but I figured I'd knock two birds with one stone.

Anyways, I own a 98 GST, and I can't say how proud I am to own this piece of work, but as all you know they all come with their problems...

So the other day I was driving back home and suddenly my dash/hvac lights just went out.. To make the story short I have searched every possible thread that could lead me in the right direction, but I'm still having bad luck.

I have done the dimmer light switch mod where you bridge the wires, and I've tried every possible combination to no avail. I've also checked al the fuses inside and in engine bay, and all seem intact, Ive checked all the lights to make sure they're not burnt out, but nothing, they're all working fine, the last thing I have to check is the wires behind the HU which is aftermarket, but sadly I just had shoulder surgery, so it's a bit difficult to do it on my own.

I got a squid question though.. How do I go about removing the panels off so that I can pull the radio out and check for shorts? Are the wires from the dimmer control the same ones that are supposed to be behind the HU?

If anyone has anymore leads as what it could be, I'd greatly appreciate it.

I'm so desperate to drive my car, as I can't due to not having tail lights at night...

Thanks in advance!

luv2rallye · Jul 23, 2015

Unplug the dimmer switch connector under the dash. It should be a 4 pin inline connector with 3 wires on it - black with yellow stripe, black, and green with white stripe. On the harness side plug, jumper the black with yellow stripe wire to the black wire. The dash lights should now go on full when taillights are on. If they don't, you have a fuse or wiring problem (which is not the dimmer switch). If they do, you have a bad dimmer switch. When you find out just how expensive a new 2g dimmer is (which is different than the 1g one), you may decide to just stay with this fix (or go used).

Archer Fabrications · Jul 23, 2015

Also check for pinched wires in your tail light harness if it shorts out itll cut the lights and dash.

1990TSIAWDTALON · Jul 23, 2015

My "new to me" 98 TSI Talon had a similar problem with no dash lights and it was the module on the back of the fuse box that was the culprit in my instance.

ghostintheshell · Jul 23, 2015

luv2rallye said:
Unplug the dimmer switch connector under the dash. It should be a 4 pin inline connector with 3 wires on it - black with yellow stripe, black, and green with white stripe. On the harness side plug, jumper the black with yellow stripe wire to the black wire. The dash lights should now go on full when taillights are on. If they don't, you have a fuse or wiring problem (which is not the dimmer switch). If they do, you have a bad dimmer switch. When you find out just how expensive a new 2g dimmer is (which is different than the 1g one), you may decide to just stay with this fix (or go used).

I tried that and no luck, I even cut all the wires of the male connector and tried every variation with no luck.

UrbanSmoker said:
Also check for pinched wires in your tail light harness if it shorts out itll cut the lights and dash.

Where exactly does the harness start? I checked the wires and bulbs on both sides and they seem fine, the break lights are working like they normally should.

1990TSIAWDTALON said:
My "new to me" 98 TSI Talon had a similar problem with no dash lights and it was the module on the back of the fuse box that was the culprit in my instance.

Which fuse box are you referring to? The one inside or the one in the engine bay?

1990TSIAWDTALON · Jul 23, 2015

The inside one . It was a module on the back that pops on. I honestly don't know exactly its function but swapped another one on and got them to work. I just happened to have a spare tho.

ghostintheshell · Jul 23, 2015

1990TSIAWDTALON said:
The inside one . It was a module on the back that pops on. I honestly don't know exactly its function but swapped another one on and got them to work. I just happened to have a spare tho.

Alright, hopefully my local auto store has it. Do you happen to know the part number by any chance?

210 dsm · Jul 23, 2015

It sounds like you blew a tail light fuse. And why are you suspecting the radio wiring? Dose anything else electrical or the HU have any irregular symptoms? I also have a 98 gst, and on our cars (and most other cars) the 15 amp fuse labeled "tail light" in the engine bay is also wired into the dash and a/c lighting. I was blowing it every other day for a few days until it stopped when I move up to 25 amp fuses. Hope this helps you get back to having fun with your car.

ghostintheshell · Jul 23, 2015

210 dsm said:
It sounds like you blew a tail light fuse. And why are you suspecting the radio wiring? Dose anything else electrical or the HU have any irregular symptoms? I also have a 98 gst, and on our cars (and most other cars) the 15 amp fuse labeled "tail light" in the engine bay is also wired into the dash and a/c lighting. I was blowing it every other day for a few days until it stopped when I move up to 25 amp fuses. Hope this helps you get back to having fun with your car.

Nah, all my fuses are fine, they've all been tested and none are blown. I suspect is the radio wiring because the original radio was also hooked to the dimmer, and 9 out of 10 when aftermarket HUs are installed they do a horrible job, hence why suspect that something back there is shorting out.

Archer Fabrications · Jul 23, 2015

In my case i had my tail lights out, and when installing them it got pinched, it was the harness that goes to the bulbs that are attached to the light itself in my case, and you have to remove the tail lights to see. Thats what I'd do

210 dsm · Jul 23, 2015

I'd highly suggest investing in a repair manual for your car. This is from the chilton book. The two kick panels on the sides of the center console each have two screws holding them in. There's a few hiding in the floor console also

ghostintheshell · Jul 23, 2015

UrbanSmoker said:
In my case i had my tail lights out, and when installing them it got pinched, it was the harness that goes to the bulbs that are attached to the light itself in my case, and you have to remove the tail lights to see. Thats what I'd do

Yeah, I checked that and it all looks gravy, I'll do it again just in case I missed it.

210 dsm said:
I'd highly suggest investing in a repair manual for your car. This is from the chilton book. The two kick panels on the sides of the center console each have two screws holding them in. There's a few hiding in the floor console also

Dude, thank you so much. That's exactly what I needed, I'll check the back of the radio tomorrow and update you guys with pictures.

210 dsm · Jul 23, 2015

You're welcome.

luv2rallye · Jul 23, 2015

210 dsm said:
I was blowing it every other day for a few days until it stopped when I move up to 25 amp fuses.

NEVER PUT A HIGHER RATING FUSE IN!!! The wiring is large enough only for the fuse rating. Higher amp fuses will allow the wiring to burn up/start a fire! If your fuse is blowing either you have a short or you have too many loads on that circuit (and you'd need to string a new wire and fuse for the additional load).

luv2rallye · Jul 23, 2015

1990TSIAWDTALON said:
The inside one . It was a module on the back that pops on. I honestly don't know exactly its function but swapped another one on and got them to work. I just happened to have a spare tho.

That is the ETACS-ECU which is an incredibilly expensive dealer only item and will NOT be your problem.

luv2rallye · Jul 23, 2015

ghostintheshell said:
Nah, all my fuses are fine, they've all been tested and none are blown. I suspect is the radio wiring because the original radio was also hooked to the dimmer, and 9 out of 10 when aftermarket HUs are installed they do a horrible job, hence why suspect that something back there is shorting out.

I hope you tested the fuses with a multimeter (just looking at them doesn't guarantee they're good - hairline crack, etc).

The only radio wire that goes to the dimmer should be a radio illumination light to the dimmer's black/yellow and only if it functions as a negative control wire (dimmer supplies a variable resistive ground). If the radio illumination light wire requires +12v it can go to the dimmer's green/white wire (which is +12v when taillights are on).

You need to start testing voltages. Start by removing the "Tail Lamp" fuse in engine bay. With tail light switch on you should see +12v on one of the "Tail Lamp" fuse pins. If you don't, either the tail light relay is bad, or the light switch isn't turning on the tail light relay (puts ground on tail light relay's green/white), or there's a wiring problem.

210 dsm · Jul 23, 2015

Thank you oh wise one, I am aware of this though. It was a temparery fix at the time and it kept people from slaming in the back of me at night. Not to mention cops LOL

.

ghostintheshell · Jul 23, 2015

luv2rallye said:
I hope you tested the fuses with a multimeter (just looking at them doesn't guarantee they're good - hairline crack, etc).

The only radio wire that goes to the dimmer should be a radio illumination light to the dimmer's black/yellow and only if it functions as a negative control wire (dimmer supplies a variable resistive ground). If the radio illumination light wire requires +12v it can go to the dimmer's green/white wire (which is +12v when taillights are on).

You need to start testing voltages. Start by removing the "Tail Lamp" fuse in engine bay. With tail light switch on you should see +12v on one of the "Tail Lamp" fuse pins. If you don't, either the tail light relay is bad, or the light switch isn't turning on the tail light relay (puts ground on tail light relay's green/white), or there's a wiring problem.

I didn't check it with a multimeter, but I did change the 15 amp fuse and still nothing, happened, I also changed the relay around, and nothing, but I'll definitely get a multimeter and make sure it's putting out power. I hope that the HU is the problem, as it's a freaking mess back there.

ghostintheshell · Jul 26, 2015

So the voltage on the tail light fuse is .8 LOL

. I think I have a short as soon as the wire harness comes out from the fuse box, the intercooler pipe clamps where rubbing on it. So I'm about to tear it apart and see.

CORRECTION: one of the prongs on the tail light fuse is putting out 24 volts and the other one is putting .8

ghostintheshell · Jul 26, 2015

What wire should I be looking for coming from the fuse box?

ghostintheshell · Jul 26, 2015

Never mind.. I think I found the problem?

ghostintheshell · Jul 26, 2015

The black goop was a melted black wire in the harness which also melted that red/black wire. The voltage kept giving me 18-24 on the tail light pin. I'm gonna fix them and see if that's the cause of this BS. I'm about to go insane cause of it. Not to mention that is hell on earth right now here in Florida.

ghostintheshell · Jul 26, 2015

And fixed!!! f*** you wires!

ghostintheshell · Jul 26, 2015

If anyone can identify that black wire it'll be greatly appreciated, it doesn't seem to affect the system if it's not connected. That thing melted all the way down.

luv2rallye · Jul 26, 2015

ghostintheshell said:
The voltage kept giving me 18-24 on the tail light pin.

That's pretty miraculous considering you only have a 12.6v battery and an alt that shouldn't ever be putting out more than 16v (normal is 14.4)! So you either are measuring it wrong (most likely - are you on a volts DC scale or do you mean resistance of 18-24 ohms?) or you're alt is bad.

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