Well its gonna be a wire tapped into the white signal wire coming off the headlight switch.

I am not a fan of dodgy wiring from previous owners. Fix it right!


Here is what the relay looks like and a "common" problem with meltage on the stock plug. Yours looks fine. Bet your relay just died and whomever was working on it didn't want to find one and bypassed it. There is the second relay underhood on driver fender.


30 seconds on google image:




Second underhood relay:




Headlight wiring diagram:

 

the underhood relay is the 'step' relay that switches from high to low beams.


if they bypassed the under-dash headlight relay, then all of the headlight power (about 120 watts with high beams using standard 55/60 bulbs) is passing through the headlight switch AND the ignition switch, which is not a very good thing, and will likely fry/melt either of those.

 

Right. I was really in a jam one time and jumped 12v from the battery to highbeam "signal" pin and at least had highbeams steady on for the drive home!

I am just trying to give some help to the OP so he can get out his multimeter and figure out what is going on. There is still a chance that is NOT his headlight relay plug, but it sure looks like it. I just ready today that on 1992 model for example its not even down by the firewall, but rather up higher in the dash.

Who knows what is really going on!? He did say he heard of headlight issues from previous owner, so I would did deep and figure it out.

I got a 740 from a tweaker one time and it had all sorts of crappy wiring and strange things like neon floor lights wired in. I guess it was his form of courtesy lights. Ha.

Without having the car here in front of me, there is nothing more I can really help with.

 

I used that google image as a reference and found nothing behind the brake, no bracket, no bolt, no hole for the bolt, no relay, nothing. But those images are for a few late 80's models so might be in a different spot for my car.

What confuses me is how the plugs white in those shots, but black on my car. Either they changed plug colors when they changed locations or its for something else.

I did run the car for a while at night with the rear foglights on with no issues yet, I'll dig deeper when I get the chance.

 

Your screename says 92Sedan, but thread title says 1990 240. Which one is it?


Again, you need to do some multimetering. It would take all of 10 seconds to trace that plug to the fuse panel, headlight switch, etc and confirm or deny if its the headlight relay plug.

 

90 Wagon, the 240 sedan was sold years ago (and I do regret selling that thing, was a tough son of a gun).

I got everything apart but the multimetering will have to wait til tomorrow, its dark out and my garage is too stuffed to work in.

I did re-check the wires to the plug and write the colors and their corresponding numbers down

1. Green
2. Blue-Yellow
3. White
4. Red

Middle slot unused

I should've taken notes from the get-go but, oh well. If the headlight thing uses 5 pins than this 4-pin bugger goes somewhere else, or the middle wire was re-routed for some bizarre reason.

 

hmmm. the seat belt buzzer is white-red, blue-yellow, yellow, and blue. and black. no, I guess not.

the electric window power relay is blue-yellow, black, red, and too blurry to read.

there's a pair of locking relays, both are 5 pin, and have multiple wires to some pins, with blue, green, black, yellow as the main wires

 

The door buzzer works fine but the seat belt buzzers mute.

Power locks work perfectly fine

 

http://www.davebarton.com/pdf/relay_84_240_dash.pdf


Well it sure isn't the headlight relay it seems. I would still find your headlight relay down there at the firewall just so you know where it is and what it looks like and check for burning or corrosion.


Maybe seatbelt relay plug?

 

Right, to check for that any any "handy work"

It might be the seat belt relay plug, the warning light will appear but no buzz, the light will go out whether if I'm wearing my belt or not.

Does the relay need to be plugged in for the airbag to work?

 

Absolutely NOT. Volvo would never be dumb enough to create a circuit like that. I did smoke my wires on my car by pinching some wires for that exact circuit down by the ebrake and burned out the yellow/blue wire for it over at the fuse box. All that wiring is gone. Chime has been long gone too. I know how to buckle a seatbelt. It has save my life at least 3 times. Everything will work fine with no chime or warning lights hooked up. I always remove mine right away. I had a 740 that would blow fuse 5 and the radio would die and the chime would stay on. I fixed the problem and threw the chime relay in the trash.


I had an accident in my 400k mile 1990 240 recently and the airbag deployed just fine. I now have a replacement airbag and no SRS codes. YOU SHOULD test for codes though. Look it up. It involves popping the cover off that says SRS in the center console and grounding it with a jumper wire and flashing the SRS light in the dash. You should do that to test SRS function. Previous hacks may have pulled the bulb! My cousin is only alive right now because of the airbags in her car saved her life in a head on.

 

Thats good, I know they're smart enough to give their cars meaty factory brakes too, meaty easy to change brakes (something my '92 Accord could've used).

The only time my SRS light popped on was when I forgot to plug in that circle behind the cluster, I'll check it sometime though.

Thats pretty impressive the airbag still worked after all these years, did someone pull out in front of you?

Accidents seem to be the one thing that can kill RWD Volvos, not mileage, not abuse.

 

I put my multimeter into 20VDC mode, black wire to the green, red to red, and this was the reading:

12.53

Moving the red mutimeter plug to the other sockets gave the same results, leaving black in green.

 

green is usually a switched power signal to something. red is generally always on unfused power.

switch the car off, measure the voltage from the green wire to ground (find a ground anywhere), hopefully its 0 volts. red to ground should be 12.xx volts. If green is at 0V, then put the meter in OHMS mode, and measure the resistance from green to ground. if its at least a few ohms, jumper the red wire to the green wire and see what turns on note that if its 12 ohms, thats 1 amp. if its 6 ohms, thats 2 amps, your jumper will need to be decent gauge wiring.

 

Red to ground is about 12, green was 0

Jumping them only caused a burning spark, I use some smaller guage wiring though, crap from cheap third party videogame controllers.

I'll test it with some REAL wiring and get back, but for now I need to put on my new sway bar bushings.

 

did you measure the resistance (ohms) from green to chassis ground with the power off ?

if that was 0 ohms, then do NOT jump power (red) to it, or you're gonna fry it. amps = volt/ohms. volts is 12.5V or so, so what I said, if the green-to-ground is 12 ohms, it will draw about 1 amp. if green-to-ground is 0 ohms, then green *IS* ground, and jumpering red to it will be 12.5/0 == infinite amps, melt down and catch fire kinda thing.

 

You measure power between the suspected wire that "should" have 12v and a good GROUND!!! Meaning, one test lead to whatever wire you are testing and then the other test lead to a known good ground. The best ground I like to use is the cigarette lighter bore.

What you need to do is find the wiring diagram for seatbelt warning and trace it out using the OHMS setting. Basically you are chasing a wire from end-to-end to see where it goes. 0 ohms means it is the same wire end-to-end. On the other hand, It will read "1" or whatever ohmeter shows for NO connection. Means it is NOT the same wire end-to-end or there is a break. If you see lots of resistance (hundreds or thousands of ohms) it can mean a shorted wire.

For example, look at the headlight wiring diagram above. See B? Headlight SWITCH. Left of steering wheel. See G? Headlight relay. You could do a test to see if that mystery plug is indeed the headlight relay by simply connecting one terminal of ohmeter to the blue/white wire (pin 56 at headlight switch), then connecting other test lead to the blue white wire plug at the relay (pin 86. only labled on relay though, not plug) and if you have zero ohms between the two it means it is the same wire!


Homework assignment: Look at wiring diagram above. Which wire at the headlight relay is always HOT 12v?


They way I learned how to read wiring diagrams was to have them in front of me printed out and spend time with a pencil tracing it out. They are usually black and white and wont have nice red colors for you to follow!

 

Green wire to ground has 12.3 vDC

I will test the headlight switch once my sway bars back on, someone didnt bother to mention that the bushings had lumps on them (intended for a different bracket setup), another reason why I don't trust ebay stuff.

 

YEP! Hot at ALL TIMES. Not just with key on. Above wiring diagram shows the Green/Red (green only in your case) going from the battery directly to the headlight relay.

Next you need to check if you have 12v coming from the headlight switch over to the relay. What color is that wire? I aint tellin ya in this post! You would need to turn the key on, turn headlight switch on and see if 12v shows up on this certain wire. It's up to you to figure out which one it is. When you turn the key off, or headlight switch off, the voltage should go back to ZERO.According to wiring diagram above the relay only uses 4 out of 5 pins. Pin 87 is the out put of the relay. There are actually TWO pin 87's on the relay here in my hand so......Like I said before, the confusing part is, wire colors change over the years and when you are just pulling diagrams off the internet you ALSO don't know if they are correct for your year. That is why you need to be able to use a multimeter and do your own tests to figure out what is what. Especially if there may have been a hacker in there before!

Those colors you listed above are pretty far off from mine, and from the diagram.... might not be the headlight relay plug afterall. If its not, you still should find out where those wires end up going AND locate YOUR headlight relay and repeat the tests. Its good practice anyways!

 

I'll get to that tomorrow, long story short my bushing/sway bar stuff has eaten up my day, its dark out. Should take me just a few minutes tomorrow to finish up, and after that I'll run more tests.