One brake light not working when lights on - JeepForum.com
Search  
Sign Up   Today's Posts
User: Pass: Remember?
Advertise Here
Jeep Home Jeep Forum Jeep Classifieds Jeep Registry JeepSpace Jeep Reviews Jeep Gallery Jeep Clubs Jeep Groups Jeep Videos Jeep Events Jeep Articles
Go Back JeepForum.com > Models > Jeep Liberty Forums > KJ Liberty Forum > One brake light not working when lights on

Introducing MONSTALINER™ UV Permanent DIY Roll On Bed LineRuffstuff Axle Simple Swap Kit!ROCK BOTTOM prices on LIFT KITS at Rockridge4wd!! WANT TO

Reply
Unread 12-18-2010, 05:15 PM   #1
d5332
Registered User
2002 KJ Liberty 
 
Join Date: Sep 2010
Location: Newark
Posts: 119
One brake light not working when lights on

LinkBack Thread Tools Search this Thread Rate Thread

#1 (permalink) Today, 05:39 PM
d5332
New User Join Date: Oct 2010
Posts: 24


Driver Break light not working with lights on

--------------------------------------------------------------------------------

HI,

I was waved down last night by a nice passerby....

Turns out my left brake light is out so today I went to change the bulb...the bulb is fine...light works fine...huh....

Realized my left brake light is not working when the headlights are on. All 3 brakelights work IF the headlights are NOT on.

I am dumbfounded...

Can anyone help me?

What would cause one brake light to not work when you have your headlights on?

d5332 is offline   Reply With Quote Quick reply to this message
Unread 12-19-2010, 02:23 AM   #2
Billwill
Registered User
2002 KJ Liberty 
 
Join Date: Jul 2007
Location: South Africa
Posts: 1,050
Most funnies regarding tail/brake lights are due to bad earthing within the tail-light cluster.If in doubt, try adding extra grounding to the bulbs, you can never have too much ground
The Sticky above, Liberty Service Manual has Section 8, Electrical diagrams. it is well worth well downloading this section as it covers all 2002/2003 models.
Billwill is offline   Reply With Quote Quick reply to this message
Unread 12-21-2010, 02:09 PM   #3
d5332
Registered User
2002 KJ Liberty 
 
Join Date: Sep 2010
Location: Newark
Posts: 119
I added a direct ground from the socket and that fixed the problem….

Did notice my wires are starting to rot…this is going to be fun…

Thank you very much for the information….greatly appreciate it….
d5332 is offline   Reply With Quote Quick reply to this message
Unread 12-24-2010, 06:33 AM   #4
Nilknarf
Registered User
2004 KJ Liberty 
 
Join Date: Dec 2010
Location: Long Island City, NY
Posts: 7
Quote:
Originally Posted by Billwill View Post
Most funnies regarding tail/brake lights are due to bad earthing within the tail-light cluster.If in doubt, try adding extra grounding to the bulbs, you can never have too much ground
The Sticky above, Liberty Service Manual has Section 8, Electrical diagrams. it is well worth well downloading this section as it covers all 2002/2003 models.
Hi. I am experiencing the same issue, but with the passenger side break light. How do you add extra grounding to the bulbs? Thanks for your help.
Nilknarf is offline   Reply With Quote Quick reply to this message
Unread 12-24-2010, 10:47 AM   #5
d5332
Registered User
2002 KJ Liberty 
 
Join Date: Sep 2010
Location: Newark
Posts: 119
Your brake light socket should have 3 wires.....mine did...the black wire is the ground....

My black wire was not connected, probably bc the bulbs have a main ground but the main ground has gone bad....

I removed the tail light, I found a place to grind away a little bit of paint, drilled a hole, added wire from the black cable on the socket to the screw I placed in the hole I drilled and tightened it....
d5332 is offline   Reply With Quote Quick reply to this message
Unread 12-25-2010, 03:44 AM   #6
Nilknarf
Registered User
2004 KJ Liberty 
 
Join Date: Dec 2010
Location: Long Island City, NY
Posts: 7
Thanks for your help. I'll give it a try.
Nilknarf is offline   Reply With Quote Quick reply to this message
Unread 12-26-2010, 07:30 AM   #7
waywardtravel
Registered User
2006 KJ Liberty 
 
Join Date: Dec 2010
Location: Panama Country and, az
Posts: 76
D5332
I work in the electronics and electrical a lot. It's very interesting that it works with the lights off. I would take a multi-meter and check continuity to ground from the light. If it has two separate grounds, one from the three wires mentioned and one somehow case grounded check both separate while disconnected . Then try the same thing with the lights on. If the resistance (ohms) changes, you have an issue to chase down. If you add another ground with that issue your creating a short even if the light lights. This will effect something down the road. I would guess it's a relay issue but assuming ground is good to make the bulb not light at all and then adding a ground makes it light means both power and ground were power at that moment. No difference of potential and you already have a short). That would also say that the ground coming from the harness (assuming it's bonded to the light well) was power.
It might be easier to check for voltage.
Lights off engine on.
Check voltage from each pin or each of the three wires to chassis ground only one should have voltage with the brake pedal depressed
Lights on engine on.
Do the same, what changed?

If the wire harness was creating the short replace it don't add a better short path.

Last edited by waywardtravel; 12-26-2010 at 08:41 AM..
waywardtravel is offline   Reply With Quote Quick reply to this message
Unread 12-27-2010, 01:52 AM   #8
Billwill
Registered User
2002 KJ Liberty 
 
Join Date: Jul 2007
Location: South Africa
Posts: 1,050
Hi waywardtravel, I totaly agree with you that the problem should ideally be traced down by means of a multimeter....if you know what you are doing! I was trained in Electrical Engineering light Current and have 34 years under my belt of working in Electronics in the mainframe Computer area. I have had to chase down about five wiring faults in my Jeep with the aid of a good wiring diagram.
If you are not an expert though...then I believe that trying a quick fix such as I recommended d5332 is well worth a try and should not cause any harm....the ground wire going to the bulbs is supposed to be "ground" so adding a shorter grounding path should never cause any harm...it may bring up a different problem altogether which may help in the final diagnosis. I do think though that the suspect ground wire going to the bulbs should be cut off at the bulb side and insulated while a completely seperate short ground is added to the bulb.
Wish I could tele-port myself to the States so that I could lend a hand
Billwill is offline   Reply With Quote Quick reply to this message
Unread 12-27-2010, 06:37 AM   #9
Nilknarf
Registered User
2004 KJ Liberty 
 
Join Date: Dec 2010
Location: Long Island City, NY
Posts: 7
Thanks for the feedback, guys. Lots of information. What if I simply replace the entire tail light housing? Would that work?
Nilknarf is offline   Reply With Quote Quick reply to this message
Unread 12-27-2010, 09:45 AM   #10
Billwill
Registered User
2002 KJ Liberty 
 
Join Date: Jul 2007
Location: South Africa
Posts: 1,050
Quote:
Originally Posted by Nilknarf View Post
Thanks for the feedback, guys. Lots of information. What if I simply replace the entire tail light housing? Would that work?
I doubt it will make any difference but I may be wrong.
I have not removed my tail-light housings for a while, if the wires are long enough maybe you can swap over left and right units, leaving them dangling, to see if the "bug" moves with the housing itself!
Billwill is offline   Reply With Quote Quick reply to this message
Unread 12-27-2010, 11:51 AM   #11
waywardtravel
Registered User
2006 KJ Liberty 
 
Join Date: Dec 2010
Location: Panama Country and, az
Posts: 76
Try the light swap if possible. I've never removed one yet.

BILLWILL The only "major" concern I have is that one mentioned the wire harness was rotting. If the light doesn't work only with the lights on and adding a ground makes it light, The odds are that ground is positive. It could very well be making contact with the 12v positive wire driving the light. Checking it will tell. Only voltage and ground on that ground wire. If it's disconnected and a new ground is run it would light but the power wire possibly making contact with the original ground is still sending power down that original ground path. This could cause many issues including fire. If it's not a broken ground issue and you happen to have night vision goggles it saves tons of time tracking a short. Not likley but it works amazingly well


Lighter note: I spent a year in electronics school for guided weapons long ago and they trained the nurses in the same location. Every time they saw us jump from even the tiniest shock OFF TO THE E.R. for an EKG. I swear all of us had patchy chest hair. That sucked
waywardtravel is offline   Reply With Quote Quick reply to this message
Unread 12-02-2013, 08:46 PM   #12
sbshealy
Registered User
2000 WJ 
 
Join Date: Feb 2012
Location: Columbia, SC
Posts: 6
I know it's been a while since this thread was last updated, but I thought I'd add to it since this forum has given me so much back. This is on a 2000 Jeep Grand Cherokee WJ.

First of all - CHECK THE BRAKE LIGHTS BOTH WITH THE LIGHTS ON AND LIGHTS OFF.

A while back (maybe 6 months ago) I noticed a brake light out while backed into a parking spot at dinner (using the reflection on the building's window). Checked it the next day, and everything was fine. Checked it a couple days later, still good.

Fast forward to tonight. A car came up on me kinda quick, just enough for me to check my brakes in the garage (using the reflection on the garage door) right when I got in (lights still on). Sure enough the driver's brake light was out. Went inside and came back out. My wife hit the brakes so I could see which bulb was the brake light before I started unscrewing. Now it worked fine (now with the lights off). It took me a few minutes to figure out that the lights on/off trick is key to really checking things out. Looking real close the "lights off" brake light is a lot dimmer than the passenger's side (like it was the daytime brake). So now, I was sure the bulb was bad. Put a new one in that I had in my tool box. Same thing - so not the bulb. Removed the passenger light assembly and swapped driver/passenger assemblies around (same plugs so easy to do). The problem followed the driver's assembly (which is now attached to the passenger side) - so all the internal wiring is good. Switched the assemblies back around to normal, then switched all the bulbs around, and the problem stayed with the driver's assembly - so not a Jeep problem and nothing to do with bulbs. I pulled both assemblies back out, removed all the bulbs, and did basic continuity testing between the two. Everything matched up fine. So now what? Looked a little closer at the driver's brake light socket/recptical/housing/contact. I noticed that the brake light's "single contact" looked a little recessed - finally found the culprit. Looking closer, it was due to the plastic housing/ring failing. Basically the stress of the bulb/screw-in/contacts/etc has taken it's toll over the last 14 years. Imagine that! Anyway... I took a screwdriver and pried the contact/plastic up a bit. The contact finally released (either it was glued or just stuck real tight) so that the contact is now raised above the plastic a millimeter or so. So the contact now will physically mate with bulb's contact. Works fine now.

I'll have to keep an eye on it from here on out. The passenger's assembly looked like it was cracking too. The two lower bulbs (turn and reverse) looked better. These two only have contacts physically across from each other that may spread the stressing a little. The brake light has 3 contacts - 2 on one side and 1 on the other. That 1 by itself is where it is failing so maybe it is more stressed with 2 opposing it.

Hope this helps the next guy. Attached is a picture that says it all - it would have save my thousand words, right? This picture shows the recessed contact and failing plastic ring. I didn't take an "after" picture.
dsc_6431.jpg

sbshealy is offline   Reply With Quote Quick reply to this message
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.
Note: All free e-mails have been banned due to mis-use. (Yahoo, Gmail, Hotmail, etc.)
Don't have a non-free e-mail address? Click here for a solution: Manual Account Creation
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.


Thread Tools


Suggested Threads





Jeep, Wrangler, Cherokee, Grand Cherokee, and other models are copyrighted and trademarked to Jeep/Chrysler Corporation. JeepForum.com is not in any way associated with Jeep or the Chrysler Corp.