Driver's side taillights...

'99 Disco II. The two top bulbs (12v,5w) in the LH (driver's side) rear taillight assembly, I guess you'd call them the running light and the side vision clearance light(?) will not light.  I swapped the same two bulbs from the RT assembly (which work over there) and they still did not light up.  I put those bulbs back into the RH assm and they DID light up.  I bought new bulbs for the LH asm anyhow and they won't light up.  I've cleaned the sockets.  These bulbs do not have multiple elements as stated in a sort of similar probelm on page 10 (I went back a ways to see if there are any similar glitches before I start a new whining.)  What I do to keep cops from giving me fixit ticket(s) is turn on the rear foggers as that gives me a running light on the left side but that's not a good answer.  Since there is only one harness coming into the rear light module, I am assuming that there is only one fuse to cover all 4 bulbs (side view, running, brake, & reverse) within the asm.  So why can't I get those bulbs to fire up?  I know this is long, but the more you know, the more likely someone will give me the Magic 8-ball answer. (yeah, I know: "Ask Again Later".)  No, I did not put a meter on the sockets but it's cold out there today!
Thanks,
Kevin in very rural Arkansas

check ever single one of your fuses. twice.

Kevin,
Never assume, there are 2 fuses, read your manual and check them out.

I've checked my hardcopy manuals and I've checked RAVE CD and can't find anything about more fuses/relays that might really help me out.  I'm not even sure where the related fuse box might be.  I've read all of the stuff on the one beneath the dash which seems to be the one that would affect the taillights but nothing shows me separate fuses for running/clearance lights vs. brake light vs. reverse light within that taillght assembly.  Once the wiring harness hits the assembly, built in wiring tracks are laid out within the taillight module itself.  Am I missing something too obvious?
 
Tomorrow, if it warms up a bit, I'll lay the meter to those sockets to see if there is juice.  But I just can't see where or why they would fail at the light sockets since the downstream light tracks work fine.  Also, the wiring diagram that I can pull up in RAVE doesn't seem to match the color coding that I have.  Is there a possibility that I have a Disco I/Disco II salvage Frankenstein?  Please say no.  I can't find a Texas/Louisiana title (a sure sign of a hidden salvage) within Carfax but there are some wierd signs of a rebuild now that I am getting into this thing.  Also, I've since found that the left (driver's side) "clearance" light up front will not light up.  I've changed that bulb, too.  I won't get started on the old problem of the front sunroof not opening and the rear sunroof leak nor will I bring up the cruise control problem (system lights up but nothing happens.  Where does the vacuum tube go from the bottom of the module on the passenger side fender?).  Seems like this vehicle was built by Morton's Salt: when it rains; it pours!
 
Kevin in the Arkansas Stix (3 hrs from any Rover tex)

Disco II lights are high on the pillars. Get a $5 test light and test the harness that feeds the lights, if you have power then check the connections of the light assembly. If no power and it is a Disco II the harness that feeds the left is behind the right tail light. That is where you tie into if you wanted to install a trailer plug.

Thanks, guys.  I wasn't able to get to it today but will do so tomorrow (Sunday). You mentioned a connector for a trailer in the right-side pillar.  I have a trailer hitch w/7-pin plug (that's operational) yet I noticed a female connector still just hanging around in beneath the right (passenger) taillight assembly. The taillights are back in place so I can't run out to count how many pins it has but I seem to think it was 7.  What is making the trailer lights connector working?  I wonder if it (the hitch and wiring) was aftermarket and it's spliced in somewhere else.  Or is this an "unfulfilled" connector for perhaps something else that was not an option on my Disco, maybe?
Believe me, I appreciate advice from this forum as I have 2 small problems: 1) I live nearly 3 hours from any even halfway major city (Little Rock & Memphis are the closest big'uns). And 2) I have a small "budget", if you catch my drift.  I retired from Las Vegas to move here and our incomes dropped 75%.
 
Thank you all once again,
Stay tuned,
Kevin in the Stix

I have the same problem on mine, but I just go and tap the lens and they come on and stay on. I believe that it is my bulbs, but I haven't tried replacing them yet. I don't drive at night that often, so it doesn't really bother me.

Just because you have running lights at the trailer plug doesn't mean that you have power going to the other side tail light. Like mac25dm said tap the light, I have to do that on my right one from time to time to get the rear bulb to come on (too lazy to take the assembly off and tighten the bulb connection inside the socket). You mentioned a connector that is hanging around on the right side, that may be what is feeding the left side. If it has OEM style trailer connector installed (it plugs between a male and female connector behind the right light) and will go down the cavity to the trailer hitch.  

My same light was out the other night. I smacked it and it came back on. I'd check any connections that might be in there.
 
The only way to find out for sure is to get a tester as mentioned and start testing along the circuit from bulb to fuse.

I'm back.  I have been somewhat "distracted" (haven't been on since 12/29).  This is a long one but the more you know, the more the problem might be pinpointed.
This is a tail light problem.  Tapping on the lenses does not help & is not how I want to "fix" it.  Let's review: Brake lights and reverse lights work in both assemblies.  The running lights (the two top bulbs) do not light up on the driver's side.  Here's what I've done to troubleshoot: working lights (from the passenger side) will not light up in the driver's side.  The new driver's side bulbs which did not work on the D-Side, DO light up on the passenger side.  Putting the newbies back into the D-Side: they don't work again.  The bulbs from P-S side (working on P-Side) tested on to D-Side (did not work) and went back to original place in P-Side where they again DO work.  Now, to add insult to injury, I've found that neither license plate lights work.  They have been replaced but they still do not work.  Why would two bulbs (out of 4) in the D-Side not light up, the 2 bulbs in the license plate light not light up, but all 4 bulbs in P-Side work fine?  Because of the way the rear light assemblies are manufactured I can't see why there would be separate fuses among these circuits.  Once the juice hits the rear light assemblies, the internal circuitry built into the light units should track to the individual lights. Since the feed to the license plates lights and the D-Side unit comes a "Y" from the harness behind the P-Side area, why would there be a split (separate fuses) in feed to D-side running lights, license lights, vs. P-Side running lights?
Are the running lights and license lights somehow connected?  Why wouldn't the P-Side running lights be affected then?  That should be just an extension of the wiring harness.  There are no fuses there.  By the way, all the wiring I have been able to inspect show no signs of cuts, breaks, or pinches, etc.
 
I apologize for running on & on but I live waaaay away from the nearest LR (3hrs) technicians and I'd like to solve this here!
 
I have the RAVE CD but am unable to discern any specific info for this glitch.  Oh, also, I do have a hitch w/the 7-pin trailer elctrics plug, but when I removed the P-Side tail light unit, it appears that the plug that should be the trailer plug source wiring is, in fact, not being used. Possible aftermarket, then.
Does any of this make sense or should I just open a damned beer & shut the heck up?
 
Thanks,
Kevin
NE Arkansas

Hi, Im new to the forum, I came here looking for the answer to this same problem. I have an 01 Disco II, and the lights are doing the exact same thing. Drivers side tail lights, and license plate light will not work, have checked all fuses and replaced all bulbs. Does anyone have an answer to this problem? Thanks

I'm the guy who started this thread.  I've never been able to solve this problem altho I must admit I've been pretty distracted and haven't ever torn into it as deeply as I intended.  Our weather has been awful since Feb up until just a month or so ago.  Then a month ago I had a heart attack so now I've been awful.  My Disco has what I thought was the factory hitch.  When I was snooping around behind both taillights I noticed a plug coming off the harness to the passenger side light.  I believe that this was intended to be the trailer hitch tie in for the factory installed hitch light harness.  Now I'm thinking (since I have found out that my dual sunroofs are aftermarket and NOT "factory installed" as stated by previous owner(s)--one has failed and the manual crank site that I'd hoped to utilize does not exist!) that perhaps this hitch is also some cheesy add on and the wiring for its was spliced in from some other bizarre location.  I've checked fuses, replaced lamps, tapped on lights (which is not the way I want to resolve this anyhow) but nothing has happened.  When I drive at night, I illuminate the rear "fog" lamps to avoid being pulled over for a no rear lights (driver's side) ticket.  Eventually I'll get back into this.  I did find an accurate wiring diagram that, if I can find it among the crap on my desk, I'll send on to you if you need it.  Oh, and if you've found the magic twanger to solve this please let me know.  I'm pretty sure this is going to be easy if I can just park this thing, put on my worst clothes, and get underneath and start tracing wires.
 
By the way, I put on Nitto Terra grapplers and they are great.  Somewhat noiseier than the horrible Pirelli Spiders that were installed before.  4x4 manners are now way up!
 
Good luck!
Kevin
Northeastern Arkansas

You need to pull the light assembly from the trk and switch it with the otherside, if it works on the pass side then plug the pass side light into the drivers side and see what happens. Does it work? If not then you need to test for power to the connector, but I am thinking that your light assembley is bad. If it does NOT work when plugged into the pass side then your light assembly is bad.
Also check your ground wire.
Since more than one trk has this problem I tend to think that it is a bad light assembly, maybe the seal is bad and water has gotten inside the light and corroded the connectors.
You guys need to get this fixed, even if you dont drive at night you still have NO BRAKE LIGHT which is not safe.
I have a Camry and half of my tail lights are in the trunk lid, drivers side tail lights in the trunk do not work, every other Camry that is the same year as mine has the same problem. Could be the same for you guys.