Ok,

While I am waiting on the claims people to get everything together to fix newly-dented Jag I figured I would go back to work on my headlights.

Low beams don't work but high beams do (including the low beams). I replaced the relay and the switch. All the same. I do NOT think it is the bulb but figured what they heck. Purchased a 9004 and couldn't figure out how to get it in.

Some posts say look for a panel under the wheel well and I can't seem to find said panel. My ROM seems do only deal with replacing a sealed beam unit but looking into the headlight it is obliviously a bulb.

Can someone send me a pic of the panel being referenced? Should I just go ahead and disassemble the entire housing from the front and try to get a hold of what's what?

Thank you,

-martin

 

Remove the light surround from the front of the headlight units. Then loosen the three screws that are in slots around the chrome fixing ring around the actual light unit. Rotate the fixing ring so the screw heads align with the round holes at the end of the slots, and remove it. The headlight unit will now come out. Unclip the H4 bulb and put in a new one. Inspect the wiring connectors, clean as needed, test before refixing. If no current to the dipped wire (there is a high beam and a low beam feed wire to the H4 and one earth wire, three in all) check the relay next.
Greg

 

I take it you have the 4 headlight set up. You might want to copy Greg and put the year and model so that in future post we know what car you have ;-)

Remove the lights as Greg says but if the low works then the H4 bulb is ok and its the wire setup. the 2 main bulbs should be H1s.

 

Ok - I did what you said and replaced the bulb (shop down the street had one). I have replaced the DIP/Relay, all fuses, and replaced the light switch.

I select low beam and nothing. I select high beam and the second filament of the low beam and the high beam comes on (as it should). Rear lights work in both positions as well as illumination on the dash.

Oh, forgot one part - I can open the relay and manually operate the internal plastic bits. When the when the dash light switch is on high beam I can manipulate it so that either high beams + low beams are on or the low beams alone. When the dash light switch is on low beams manipulating the relay does nothing.

I am at a complete loss as to what to check next. Everything worked fine when I got the car.

Much appreciated.

-martin

 

USA market car? What year?


I'm a little confused by what you're saying

I wonder if you're turning the headlight switch to the *fog light* position....which, by design, extinguishes the low beams

Cheers
DD

 

I am an IDIOT.

The stalk selector wasn't plugged in all the way. Looks like at some point when the lower internal panel was removed to switch a fuse is became partially unplugged.

I spent almost $200 in parts and all I needed to do was check that one connector.

 

Isn't the first click for "park lamps"?

Anyhow, the low beam circuit shouldn't be that hard to figure out....famous last words. I have a 1989 diagram...pretty sure 1990 is the same.

Voltage comes from the headlight switch, on the solid blue wire, to terminal 56 of the headlight relay. Voltage exits the relay on the blue/red wire at terminal 56b. From 56b the wire branches to fuse #2 (right side low beam) and fuse #4 (left side low beam). Form the fuses voltage goes to the bulbs. With a test light or meter you should be able to find out where the voltage is/isn't going.

Presumably the grounds are OK as the diagram shows both left side bulbs grounding at the same point and both right side bulbs grounding at the same place.....which, from memory, will be under one of the fender bolts on either side, all the way forward. Couldn't hurt to check/clean the grounds on general principles, though.

Are the fuse clips clean?

Give the wiring at the fuse box some wiggles. Any change?

Cheers
DD

 

I may have mis-spoke here. Having a brain fade.

The fog lamp setting will extinguish the high beams for sure....but I can't remember if the low beams are extinguished as well.

Cheers
DD

 

See my edit to the post above. The stalk selector wasn't operating the relay correctly when I turned the lights on. A firm re-connection fixed everything right up.

So I purchased a relay, one new bulb, and a light switch for nothing.

Oh well - I have spares now I guess.

-martin

 

Got it !

Good work.

Cheers
DD

 

Not an idiot.

Or, if you're an idiot, we're all idiots. We've all been there before !

Cheers
DD

 

Low beams on and fogs on, when you select high beam fogs will go out.

 

On some models, including mine, when the rear red fog guard light is on, the system prevents high beams from being engaged.
Greg