I have spotted yet another electrical glitch with my XJ40 .So, the problem is (intermittent) neither my tail lights (plate lamps too) nor parking lights come on when I pull down the light switch but my headlamps illuminating as they are supposed to be .
The funny thing is that I see neither bulb nor fuse error message on my dash or gauge cluster readout . So, what's running in there ?


I tapped the lights but no avail ( lol at this comical icon )

 

It may actually be your switch, Caddy. The contacts inside the switch that cause your parking lights to come on may be out of sorts. I never trust the error indicators on a car, since they can be just as faulty as the things they claim are faulty (if that made sense).

 

Don't know what mileage you are doing on a monthly basis, but if this problem only occurs towards the end of the month or after a particullarly long trip, it may be that you are getting near the end of your monthly CO2 allowance, and your car is going into automatic energy saving mode (AESM) by intermittantly shutting down the rear lights to compensate.

You might want to check to see if this issue generally disapears during the day when the global output from the car is lower, and then re-occurs at night when it is higher.

But, you may also want to have a look at the connectors to the rear lamp relay modules situated behind the side pannel carpets in the trunk. They may be a bit loose or (don't know your location) they could be suffering from condensation.

You will also find a set of connectors behind the pannel covering the back of the interior trunk/boot lid behind the rear number plate. Again check for looseness and condensation.

Get out the old WD40 again.

LOL

 

Hi,

It could be the switch, but if your car is a 1993 or 1994 battery in the trunk car, these do sound like classic symtoms of a problem with relay module "H" - DBC10009 - the one with the yellow base/connector under the dash on the passenger's side. If you can borrow one from another 93 or 94 XJ40 which has no light problems I suspect you'll find your problem is cured!

David

Edit: If this relay module is the problem, sometimes a sharp tap to the underscuttle panel on the passenger's side below the glovebox/passenger's airbax can (briefly) cure it.

 

Thanks guys for your inputs , I will be starting with the connectors ,I think there is something loose that needs to be tighten
Translator, your post crack me up , I can't stop laughing

 

I was sitting here wondering at Translator's post...lol. I'm not yet that familiar with Jags, so I was like, what the heck...?

 

Hi...not meaning to hi-jack this thread with my own problems, but I do have a simular situation. I DO have a "light out" warning lamp on. After an inspection of the car here is what I found. My left "courtesy brake light" in the rear window is out. Replaced the bulb and it still would not light up. Also my rear parking lights do not light up at all and I just noticed that my "courtesy light" in the trunk is completley missing...just wires hanging there.

So my question is....WHAT DO I DO NOW??? LOL

peace out,
daddy

 

Got you thinking, guys, though, didn't it;-)

Hope it does turn out to be a bad connection.

 

Great news or not here goes my last update lol
A few mins ago, I opened the door and my map lights lighted up (those also quite working yet another intermittent problem) . I was like "hhhmmmmm some magic happens in here " Then I started the engine , pulled down the switch to "A" and my parking lights , tail lights all lighted up as they were supposed to be
I can't help but think if there was a bad connection why on earth all the lights lighted up without touching anything ? opppssss wrong smiley
(this one should be correct choice lol )
My inference is
1- If the map lights illuminate or light up when you open the doors , everything works normal
2- Parking lights has nothing to do with the rear tail lights ,I mean your parking lights might not be working but tail lights could.
3- Map lights might not light up but tail lights might be running
So, if the tail lights lights up , your park lamps might not be

 

Think I need a quick glossary update here;

US English/UK English
Map Lights = Interior courtesy lights?
Parking lights = Side lights?
Tail Lights = Rear Side lights?
Brake Lights = Brake Lights?
Fog lights = Fog lights?
Parking Lights = ?????????? where are they on this car?

I'm thinking we may have a different setup in Europe.

Please confirm/correct accordingly, cheers.

Can't see what the map lights have got to with any of the other lights, as you can turn these on/off from a separate switch and they are on a different circuit.

What happened when you closed the door, did the lights stay on or go out.

I'm still in the land of the bad connection/relay/switch because a loose connection/sticky relay/faulty switch can give an itermittent fault, which may, or may not, appear, or disapear without any apparent input from you.

EG. closing the door, stating the engine, driving over a bump etc etc. can be enough of a jolt to disturb the connection/relay one way or the other.

I know you said no warning lights on the dash but is there anything on the VCM when you press it?

You should check the following fuses with a test light. (but pull them as well to look at the terminals for oxidation, crud etc. and put them back firmly.)
Left box, B8, C7.
Right box, B2 (switch), and B8, C7.
Center box, 1, 3. Test these two with ingnition on.

All the rear lights go through one of two lighting modules one on the left and one on the right . The front side and marker lights also have their own relays, left and right, but have common fuses with the rears, see above.

Hopefully this will sort the problem because at this stage you've not had to start dismantling the dash to get at the switch.

All the best,

 

I think I better show some pics of the lights so that we can shed some 'lights" on our issue lol
Park lamps are the square marked in white ,just fitted onto the front bumper lol
Tail lights are actually rear lights as you can see at the 2nd image
Map lamps or reading lamps are two pieces square lamps that normally turn on when you open any door even w/o pressing the button
Thanks for your questions related to the problems and here you are :

When I closed the door interior lights (reading lamps) turned off which was very normal and turned on with the button

Nope, there is no anything when I press the VCM button

Thank you for your tips I am taking them down to check out . Now, everything seems normal since my last update

 

Damned gremlins. I hate those little things.

 

I don't think Caddy is a "gremlin", he's just hard to understand some times...

 

Thanks for the vocab' illumination, in UK English I would probably use "front marker lights or side lights" because they are activated on position one on the switch, but "parking lights" is also fine because now I know what is meant.

Hope everything stays working OK until next time. Don't forget that the 'mains' position 2 only work when the ignition is on.

Thanks also for the pics, they gave a very quick confirmation that we were in fact talking about the same thing.

(daddy, if you pick this up, can you also show a pic of your non working in the rear window lights because I have never seen them over here. I've got a 92 and a 94 (spares) XJ40, but stick up a separate post so hopefully more people will dive in with help. I wouldn't worry too much about the in trunk/boot light missing even when it works it's not much use, and like the fridge, how do you know that the light goes out when you close the door?)

Keep safe,

 

The lights run perfectly but today ....Well , the problem I notice is I hear a clicking sound when I open the right front passenger door and the map light not turning on . I don't hear any clicking sound when I open rest of 3 doors . (it can only be heard right front passenger door )
I tapped the area above footwell ( where I hear the clicking sound which indicates map light not turning on ) still nothing .
BTW, I checked all the fuses and all of them replaced new .
Park lights , rear lights , licence plate lamps turns on and off on their own within a few minutes while the car is idling .
This is very ridiculous

 

If you drop the pannel above the foot well (just a few screws) you will see assorted relays/computer etc. Have someone open the passenger door while you have your ear listening to them you may be able to spot the clicking one.

If you can't spot it this way, try putting a finger on each one in turn and then open/close the door each time. If you feel the "click" you will be in the right area.

You could then always make a temporary swap with one of your other good relays to see if this makes a difference.

Check the connections to these relays

The map light could also be a duff door switch or broken wire, causing a momentary short when you move the door, the clicking you are hearig could be temporary arcing from a broken wire.

 

I still think your exterior light problem - the tail lights not coming on with the headlights etc, sounds like you have a faulty relay module 'H' DBC10009 - the one with the yellow base under the passenger's side dash. These multi function modules are unique to 1993 and 1994 model cars, and this particular one (DBC10009) is a known failure item.

David

 

Thank you , just in case I will contact and ask that relay ,it seemed fine I have to set my mind at ease
Translator, a friend told me that I needed a new door actutator for the pass door regarding map light problem .

 

The lights seems fine ( I haven't had them replaced )but the connectors,fuses,relays (fuses replaced ,Fuse 1-2-3 ).Those three also seem fine though . As for the door actuator , it would be changed regardless of its condition .

 

db,Thank you as you pointed out we found the module . There are two of them one (you told me ) running the exterior lights and the one next to it turns on / off the interior lights .
Thank you very much indeed , I will be ordering these two (just in case ) .I hope this problem will be gone forever thanks to your helps