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Ive got a 93 GS with CC and rear wiper(no airbag). I just replaced the signal switch. The wipes side all works. The turn signals both work. But I can't get the headlights or interior lights on the cluster to work. All the insides fuses are good. I checked the engine bay fuses. The HEAD fuse did have burnt marks on the bottom, but didn't pop. I replaced it anyway.

My question is, could this be the relay? I know the relay is on the other side of the engine bay. My other question is, when I replaced the switch, I noticed an unplugged wire that's connected to the ignition plugs, on the left side. It has a small black adapter to it. It does have a acc power supply to it. It can't be for an airbag, cause I got it from a 92/93 GS, and I didn't see an airbag when I pulled it. I looked all around underneath the dash, and can't find anywhere to plug it in.

Anyone can look down under there steering wheel, to the left side and see where that black plug goes, that would be great.

headlights relay could be the source of your problem, use the online manuals for locations of the components. As for interior lights not working that is usually a fuse problem, if you mean when you open the doors they dont come on then check the door pin make sure that the screw that holds it in is not loose or corroded with rust. Check the interior fuse panel again with a test light verify that all fuses are good by touching both sides of the fuses with the test light.

Okay, did a few things. Found where the unplugged adapter goes. Right under the ignition, where the key goes. I think the manual said it's to read the key or something. Not for the headlights, so that's not a priority.

Bought a brand new relay. Unplugged all 4 relays on the left side engine bay. With the brand new adapter plugged in, the headlights still didn't come on. I plugged in 2 different turn signal units, nothing. I tested all the wires to the headlight bulbs, gnd and pwr wires both work, the lights did come on. So the problem is between. I double checked all the fuses, there all good.

Anybody have a clue? I guess my only option is an electrical shop. I ran out of suggestions.

headlight relay is inside the car drivers side up under the dash if you look up under there you will see a bank of relays, try turning on your headlights you should hear and be able to feel 1 click if not then you have a bad relay.

Where did you get the switch from? I'd say it's bad as well.

The headlights are on a separate relay from the dash lights (TNS). It's pretty unlikely that they would both go at the same time. The column switch, on the other hand, is a common candidate for failure.

Newfie_dan wrote:try turning on your headlights you should hear and be able to feel 1 click if not then you have a bad relay.

Not entirely true. If the switch doesn't work, the relay won't click at all.

My original turn signal unit was dead. The replacement, and the other one I have does make that click sound when you turn the switch. So that must mean the relay is good. So what your saying is that there are too relays for the headlight? The manual showed the one in the engine bay, and Kragens sold me the same relay that goes there. I"ll check under the dash.

I did get another column switch too. Cause my dash lights don't work either. I'm hoping I don't have a working one. I'll try and grab a few more to test. If anyone has one that does work, sell it to me, so I can mark that off.

My original turn signal unit was dead. The replacement, and the other one I have does make that click sound when you turn the switch. So that must mean the relay is good.

Sorry. I thought you were saying you installed a new combo switch. The turn signal unit has nothing to do with your headlights. If your turn signals work, forget the flasher unit.

So what your saying is that there are too relays for the headlight?

Not quite. The headlights run off of one relay (headlight relay), and the dash lights/illumination lights run off of another (TNS relay).

The manual showed the one in the engine bay, and Kragens sold me the same relay that goes there.

I don't know what manual you are looking at, but trust me it's under the dash. Anyway, almost all of the relays in the MX are the same, minus a few that are lower power. In fact, they probably all have the same part number. It's really just a standard automotive relay. You can probably still use what you bought, providing the current ratings match.

When you turn on your headlights, do you hear a click? If you do and your headlights still don't work, then you have an electrical problem. If you don't hear a click, then you either have a bad relay or a bad combo switch. And like I said, it would be silly if both the headlight and TNS relays went bad at the same time, so my money is on the combo switch. Get a new one at the junk yard and try it out.

So I think what I need to check is the relay under the dash, and change the dimmer column switch. After that, I just might have an electrical problem. Thanks.

Yup. That's the most logical way to approach it. If it turns out to be electrical, it's not that big of a deal to diagnose yourself. Just tedious...

Ok, looked under the dash. Saw a few relays. Unplugged them all. Saw 2 of them were burnt. Replaced one and the dash, tail, corner lights all came back. That's a start. I'm guessing the other burnt one is for the headlights. I threw another relay in, but the lights didn't come back on. I'm going to change all the harness wires, cause I don't like burnt plugs. Maybe that will sold it. Since the dash lights came on, I know the column switch is good. I'm getting there, slowly.

Well, if those relays are burnt up, you should really check out the rest of the circuit. Wires don't just burn up for no reason. Did you add any lights or tap into those circuits at all? Maybe the harness is damaged somewhere? Test the circuits in question to make sure there isn't a short somewhere. If there is, then the new relays/wiring will burn up as well.

I would think that there is a short, because if you just overloaded the circuit, then the fuse SHOULD blow. If not, then there's a problem. Start by testing continuity from each power wire on the relay to ground (white/red, red, and red/white). If any of them test positive, then you have a short.

It was most likely your rear defrost relay that was burnt up. Its a common one in our cars. The reason behind its burning up is quite simple really. They set it up so that there is a 40 amp fuse feeding the power to the relay, there are also a few other accessories that are connected to that 40 amp circuit as well, all you need to do to burn up that 20 amp relay is have a few of those accessories running along with rear defrost. Once the current in that circuit exceeds 20 amps you get burnt wiring. I connected an inline 20 amp fuse to protect my relay as fuses are cheaper than a relay, I usually have some 30 fuses kicking around anyhow. I am a mechanic and I grab some anytime I make a trip to a j/y for spares. Anyhow once you have the correct relay replaced I would check and see if you have power at the headlights with a test light, it may be a ground issue now. Here is the link to help you ID the correct relay and its location
http://www.mx-3.com/manuals/showimg.php ... Z2-042.gif]

I saw that relay diagram before. The right diagram doesn't really look like the relays under the dash(position). When your in the car, the two closest relays to the left are the ones that were burnt. I'm going to replace all of it. I've tested the wires/fuses in the engine bay, there all good. If there is still no headlights, I guess I have a short somewhere in the firewall.

Newfie_dan wrote:It was most likely your rear defrost relay that was burnt up. Its a common one in our cars.

Then why did the dash lights come back on when he replaced the relay?

2fazed wrote:If there is still no headlights, I guess I have a short somewhere in the firewall.

It's pretty well protected where the harness passes through the firewall. A short somewhere in the harness is pretty unlikely unless you've been splicing wires. Plus, when wires burn up they usually burn up on the ends, so check all the plugs at the fuse boxes (the one under the hood especially).