Bad ground at the light fixture.

Earle

"alaskanative" <alaskanative01@hotmail.com> wrote in message
news:d646f062.0307310712.5f41c845@posting.google.c om...
> The left rear brake light on a friends Grand Cherokee is acting
> up. When the lights are off, it works normally. But if the parking
> or headlights are on, the brake light is not on at all or only very
> dimly.
>
> We have checked and replaced the bulb, and cleaned the contacts, to no
> avail. We have even replaced the passenger side bulb just to be sure.
>
> Anyone have any thoughts?
>
> I did a google search and this question has been asked MANY times, but
> never an answer. Did any of you ever get this problem fixed?

 

The left rear brake light on a friends Grand Cherokee is acting
up. When the lights are off, it works normally. But if the parking
or headlights are on, the brake light is not on at all or only very
dimly.

We have checked and replaced the bulb, and cleaned the contacts, to no
avail. We have even replaced the passenger side bulb just to be sure.

Anyone have any thoughts?

I did a google search and this question has been asked MANY times, but
never an answer. Did any of you ever get this problem fixed?

 

I concur.

When the running lights are off, the brake light filiment is getting a
ground through the running light circuit, when the lights are on, the ground
source isn't there and the brake light does not come on.




"Earle Horton" <enfermero_diabolico@registerednurses.com> wrote in message
news:bgbbr9$mspv2$1@ID-147790.news.uni-berlin.de...
> Bad ground at the light fixture.
>
> Earle
>
> "alaskanative" <alaskanative01@hotmail.com> wrote in message
> news:d646f062.0307310712.5f41c845@posting.google.c om...
> > The left rear brake light on a friends Grand Cherokee is acting
> > up. When the lights are off, it works normally. But if the parking
> > or headlights are on, the brake light is not on at all or only very
> > dimly.
> >
> > We have checked and replaced the bulb, and cleaned the contacts, to no
> > avail. We have even replaced the passenger side bulb just to be sure.
> >
> > Anyone have any thoughts?
> >
> > I did a google search and this question has been asked MANY times, but
> > never an answer. Did any of you ever get this problem fixed?
>
>

 

"Jeff Strickland" <crwlr@yahoo.com> wrote in message
news:viifd1jbqt1k0f@corp.supernews.com...
> I concur.
>
> When the running lights are off, the brake light filiment is getting a
> ground through the running light circuit, when the lights are on, the
ground
> source isn't there and the brake light does not come on.
>
>
I know someone with the same problem. where is this ground? If I remember
correctly, the housing is held in by two screws, but they run through a
plastic tab on the light fixture, no metal.

Charles

 

I don't know the exact structure of the lamps, but the description of the
problem is classic loss of ground.




"Charles Perry" <pipesandtobacco@hotmail.com> wrote in message
news:bgbf9h$mdh8i$1@ID-103962.news.uni-berlin.de...
>
> "Jeff Strickland" <crwlr@yahoo.com> wrote in message
> news:viifd1jbqt1k0f@corp.supernews.com...
> > I concur.
> >
> > When the running lights are off, the brake light filiment is getting a
> > ground through the running light circuit, when the lights are on, the
> ground
> > source isn't there and the brake light does not come on.
> >
> >
> I know someone with the same problem. where is this ground? If I
remember
> correctly, the housing is held in by two screws, but they run through a
> plastic tab on the light fixture, no metal.
>
> Charles
>
>

 

Or the contacts inside the housing ... (this is the most common area for
this problem)

Another thing is that the bulb itself has an open filament. This is even
more common than the socket problems in the housing. I know you said you
replaced the bulb, but did you install another bulb with the same problem? I
would be taking a known good bulb from the right side and plugging it into
the left side. (I would really be getting my volt meter out and testing the
bulb and socket, but barring owning a volt meter, the switch-test is the
next best thing.) If the problem follows the bulbs, then you have a
defective bulb, or handful of defective bulbs. If the good bulb no longer
works in the bad socket, then mysteriously works again in the good socket,
then you have a socket related problem.




"Charles Perry" <pipesandtobacco@hotmail.com> wrote in message
news:bgbs1p$n7krs$1@ID-103962.news.uni-berlin.de...
>
> "Jeff Strickland" <crwlr@yahoo.com> wrote in message
> news:viip9lm5ihsc74@corp.supernews.com...
> > I don't know the exact structure of the lamps, but the description of
the
> > problem is classic loss of ground.
> >
> >
>
> I was afraid of that. The entire assembly is plastic. There is a plastic
> strip attached to it that screws to the body (inside the hatch). That
means
> chasing a wiring harness problem...yuck.
>
> Charles Perry P.E.
>
>

 

Charles Perry wrote:

> "Jeff Strickland" <crwlr@yahoo.com> wrote in message
> news:viip9lm5ihsc74@corp.supernews.com...
>> I don't know the exact structure of the lamps, but the description of the
>> problem is classic loss of ground.
>>
>>
>
> I was afraid of that. The entire assembly is plastic. There is a plastic
> strip attached to it that screws to the body (inside the hatch). That means
> chasing a wiring harness problem...yuck.

Head for your local Radio Schlock and pick up some twin alligator
jumper clips and a cheap voltmeter if you don't already have one.
You can use the clips to temporarily tie the ground to the nearest
good hunk of bare body metal. If that fixes it, the volt/ohmmeter
may help find the loose and/or crudded up ground. A Factory Service
Manual wiring diagram showing the splices and such helps keep you
from taking a BFH to it.

 

alaskanative wrote:
> The left rear brake light on a friends Grand Cherokee is acting
> up. When the lights are off, it works normally. But if the parking
> or headlights are on, the brake light is not on at all or only very
> dimly.
>
> We have checked and replaced the bulb, and cleaned the contacts, to no
> avail. We have even replaced the passenger side bulb just to be sure.
>
> Anyone have any thoughts?
>
> I did a google search and this question has been asked MANY times, but
> never an answer. Did any of you ever get this problem fixed?

bad/rusty 6pin connector to the tail lamps.

http://members.***.net/wilsond/Fixes...mpfailure.html

(some day I will do a better page than that...)