New from Colorado. Of course I need a little help.
 

Always a bit scary joining a new community. So many new people. So many ways to get things wrong.

I just got a 2007 Wrangler X. I'm not exactly new to Jeeps as a brand, because traded in a 95 XJ that I spent a lot of time learning how to fix. That was all pretty easy stuff, though.

This is new and intimidating. I mean, it's wonderful, finally having the general type of Jeep I've wanted since I was a kid. But I just ran into my first 'what oh no someone help please' problem.

My passenger side tail light has some sort of WWII gremlin living in it. I will try to be as specific as possible:

• When I turn on the headlights, sometimes that specific tail light will not come on.
• It will come on if it's thumped in precisely the right spot, although the force and precise spot may change slightly.
• Brake lights work.
• Turn signals work.
• The problem seems to be associated with opening and closing the rear door.
• All other lights seem to work.

Other details: there is a tow package. Maintenance records list it as being installed years ago.

It's obviously an electrical problem, but I'm not sure what to test, or how. I don't even know what search terms to use. Nothing I've found so far matches exactly, and my 'just enough to get myself hurt' levels of electrical knowledge is only good for 'what is this it makes no sense'.

So here I am, hoping for a little help. Maybe someone had this exact problem and can walk me through it?

Welcome and you are in one good state to OR in. Electrical issues are extremely difficult to troubleshoot over distance. With these older Jeeps (and I preach this all the time) an owner better get good at wiring troubleshooting or get broke. One or the other. All I could offer is broken wires (due to door moving and turning light on/off) or grounds. First thing to do is buy, beg, borrow, steal a GOOD set of wiring drawings and use them. My Jeep is 2008 and always has some small thing come and go but with my V8 in it the motor always runs regardless of what the Jeep ECU does.

When weird electrical things like this are happening, my mind immediately goes to grounds. Sounds like this is just the running light when the headlights are on. I'd probably start by disconnecting that wiring harness at the taillight and probing the harnes with a multi meter......black to a known good ground and red to the pin for the running light 12v which should be easy to determine. is the power flickering from time to time? is it always constant power when headlines are on as you'd expect? anything finicky? Determine the pin in the harness for the ground wire and test again using that ground. any difference? on a jeep that old you could have a damaged ground wire, or a different issue.

Yeah. I have a lot to learn. What I might do, if I can work up the nerve to do it, is ask the guy across the street who has an older, heavily modified Jeep and a background in electrical engineering to teach me the dark secrets of testing electrical problems. He might be willing to help. He spent a lot of time looking at it when we brought it home, doing what I did at the dealer but with more experience and what seemed like genuine curiosity about the differences in the 'newer' models.

You might be surprised how many helping hands folks are willing to lend, especially when someone is wanting to learn rather than just have something done for them. If he's a beer drinker, a 6-pack often goes a really long ways to as a nice gesture!

Everything I know about him is that he might be close to my dad's age, possibly where he came from, and he put a sneaky anti theft device and a manual throttle control knob from a Cessna into his Jeep. Also, he routinely strips out the safety switches from his electric lawn tools because he finds them annoying.

I've made notes of your advice, though, and I'm hunting for some wiring diagrams now.

Update:

I am not the smartest person.

So I did what I said I was going to do and asked the guy across the street. He was glad to come over and help.

And he pointed out that the bulb in question was burned out. I didn't even see that. The filament was V shaped and would jostle in and out of contact.

So, parts store, bulbs, and it's fine now. Nothing that previously recreated the problem causes it again.

He also took a moment to show me how to test the battery, declared it very good, and said if I ever need more help to just ask.

I feel very dumb for not seeing that, or even knowing it was possible.

The cost of feeling like a dufus for a few moments is nothing to gain a new friend :wink:. I'm telling ya, there are a lot people out there that are willing to help people that want to learn the knowledge that they know. Your neighbor probably didn't think much of it at all, and now you have a good contact with him!

Sounds like a good friend to have. Bulbs have filaments and can flicker on and off. Also, one thought I had would have been to check the socket itself. I have seen those get corroded and/or simply worn to cause odd issues like you described. Glad it is all resolved and welcome from GA!

I just never would've thought of it. I was ready to chase down some short in the wiring because obviously it's a worst case scenario because once a bulb is burned out it's burned out. They can't possibly be 'only a little dead'.

And now I know.

And now I know the guy a little better, too.

Now I'm on to figure out more basic stuff: what oil, whether Wix is a good choice like it was for my old XJ, how to make the soft top zippers a little easier to work. How to actually work the soft top. Whether or not I can clean up the headlights enough to make them better. How to actually get at the fog lights in the winch-holding bumper. Figure out what I want to do about the broken glove box latch. Learn how to clean the reusable air filter. Learn how to take care of the paint because it's actually nice and I find myself wanting to keep it that way.

I also need to build a collection of 'how to' references like I used to have for the XJ. Forums and YouTube are a big part of that.