Dash Lights flicker when headlights on.

Hello there,
I have a 2000 LHS has recently begun flickering the dash lights when
the headlights are on. This also applies to radio. This does not appear
to happen during the day when the head lights are set on auto. Any
ideas? This is driving me buggy.
Thanks

 

There was a TSB out on applying dielectric grease to the headlamp switch
connector for this problem, sometimes it fixed the problem the other times
the headlamd switch was the cause. If I were you, I would replace the
headlamp switch

Glenn beasley
Chrysler Tech

 

Glenn's right. Over on the 300M Club
(http://300mclub.org/forums/index.php, LHS - 300M - essentially the same
car), this is commonly referred to as the "light show" problem - lots of
threads and posts on it - it's been beat to death.

I would add to what Glenn said by saying that you can usually (but not
always) stop the light show by simply moving the instrument panel dimmer
knob to a different position. Also, try turning the knob thru its range
of motion back and forth several times (it's a potentiometer - the
success of that depends on if the problem is dirt or corrosion on the
element and wiper that can be wiped off or if the wiper is not making
good contact with the resistance element due to wear or heat damage).
Last resort: change switch.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

I had the same issue with my 2000 Concorde and took it to the dealer.
It was under warranty and they said they replaced the switch but it
continued to happen. I found that the problem was most prevalent when I
had the thumbwheel turned up so the dashlights were at their highest
illumination. Turning the brightness down just a tad makes the
"flashing" stop. Sometimes it returns but a minor adjustment as I noted
above takes care of the issue for a good long time. Hope this works for
you as well.

 

Thanks guys. I'll try out your suggestions and if necessary I'll get a
new switch.
Glenn Roy

 

a new out of the box switch may be bad also, had that happen a few times

 

No idea, but I have same symptoms on a 1998 Dodge Grand Caravan Sport
dash lights/radio.

 

Hi...

Taking a big chance here. (Catch me, Bill

If by radio you mean the radio display (sound is good, and not
"flickering") then the only possible component failure that could
cause this problem is the light switch itself, and/or the connections
to the switch.

Take care.

Ken

 

No, by this I mean dash lights flicker and radio sound dies out
intermittently too.

 

No, by this I mean dash lights flicker and radio sound dies out
intermittently too.

 

OK - that's a different ball game. Sounds like you may be experiencing
a main power or ground connection problem somewhere (or protection
circuits that may be common to dash lights and audio). Do your
headlights flicker too?

This is now more of a troubleshooting problem - meaning all symptoms
(such as are the headlights flickering too) and tracing power and
grounds with schematic and multi(volt)meter.

If your headlightas also flicker, that could narrow it to the main power
or ground, but if they are not flickering, then it is more likely a
common branch (fused) circuit.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Includes headlights; I was guessing voltage regulation, but maybe not.

Will check the feeds and grounds.

Thanks, and Happy New Year.

 

Followup: I just looked at the schematics for your LHS. There is no
fused branch that is common to the audio system and your dash lights.

Unless I'm missing something, it has to be a main power or ground - and
I bet if you pay attention at night, you will notice that your
headlights are also flickering. If that's the case, main things to
check are: Both connections at battery; positive jump post (all power
except the hot wire to the alternator go thru that junction); Main
ground - AKA negative jump post on the passenger side strut tower (one
stud/nut).

If you find that your headlights are not flickering, then I will at that
point be officially confused - unless you have other pertinent info. to add.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

That was a very important piece of information that you have left out.

OK - listen very carefully - lest you think I am casually making guesses
as to the cause of your problem, I speak as the owner of two Concordes
that are the same car electrically. I have experienced and solved the
*exact* problem. I have seen the same problem reported on the LH
car-specific forums - and the almost always turns out to be one of the
following:
(1) A corroded/loose connection at the battery
(2) A loose connection at the positive jump post
(3) A loose ground (AKA negative jump post on passenger side strut tower).

Most likely it is (2). That junction carries *ALL* power for the
vehicle with the exception of the hot wire to the alternator. It is a
stud with three cables clamped on a stud - one cable from the battery,
one cable to the starter, one cable to *EVERYTHING* else (lights, dash,
radio, etc.). A loose nut on that stud means poor clamping (high
resistance, large voltage drop, lots of heat) of the cable terminals to
each other. Symptoms can be ecxactly what you have reported, or starter
intermittently not working, or the two occurring randomly as the quality
of the connection among the three cables changes with temperature,
vibration, phase of the moon...

Be aware that the nuts on the stud may *seem* tight, but if they have
been loose for a while, the threads can get heated, galled, and lightly
welded to the stud, and *appear* tight when actually they are loose
(i.e., not clamping the cable terminals, but the nuts don't turn because
the threads are arced together from heat and electrical arcing). To be
sure they are actually tight (i.e., actually clamping the terminals and
not just binding threads), back one of the nuts off (either one - to
break the threads loose), and then *re-tighten* with torque on the high
end of reasonable.

NOTE: Careful when wrenching the nuts on the positive jump post stud -
if your wrench touches any surrounding metal (ground) while it is on
those nuts (direct connection to battery +12V), you will have lots of
sparks, and possible damage or injury - it would be best to disconnect
the ground post while working on that.

But also check (1) and (3) as they have been known to be the cause of
the same problem.

You're welcome - same to you.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')

 

Appears to have been (1), although I wonder why all of a sudden, other
than a quick temperature swing. Will continue to check the other 2
psbl causes.

Thanks again.

 

Hi...

My turn to add to your thoughts, Bill

Disconnect completely the battery negative, then and only then work on
the positive post and mid-point connections. Put the battery negative
back as the last step in your repairs, and voila! Virtually zero risk
of a slipped wrench or dropped tool or piece of jewelery shorting anything.

And I'd not only check for tightness, I'd suggest taking 'em apart, then
polishing things up with a wire brush or piece of sandpaper until
they're nice and shiny.

Finally, I'd do it now, before it really starts to cost you. If the
voltage is varying enough that you can see it in the headlights, it
won't be long before you're replacing light bulbs, the radio, the
computers, and whatever else that really doesn't like the rapid on/off
sequencing.

My usual disclaimer; not a mechanic, just an old retired electrical guy.

Take care.

Ken

 

Good advice. However, disconnecting the negative ground point
(passenger side jump post) effectively accomplishes that without having
to access the buried battery (PITA). (Couldn't let you one-up me!!
Just kidding - neither one of us looks at it that way.)

Good point.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
address with the letter 'x')