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Car Forum / Ford / Ford Cars / November 2004

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98 Sable - Strangeness of Pulsating Lights

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Damaeus - 07 Nov 2004 08:59 GMT
Recently my headlights, dash lights, radio readouts and backlighting, dome
light, tail lights, etc... have all begun pulsating intermittently and at a
steady rhythm.  Revving the engine a little does not stop the pulsating,
nor does it affect the tempo of the pulsations.  Then all of a sudden it'll
stop pulsating and everything will be normal.  This happens even when the
A/C and radio are off.

Now I don't know for sure if this is what caused it, nor am I 100% certain
that this is when the problem started, but a few nights ago I was asked to
give someone a boost with some jumper cables.  I'm not sure if there's any
way that could have affected anything, but it was after that when I first
actually noticed the problem, I think.

I checked the battery cables and they're good and tight... so tight I can't
even move the sleeve around the post with my hand.

My friend has a '98 Taurus and he claims his lights pulsate, too, but I'm
not sure if we're talking about the same thing or not.

Any ideas at all about this one?

Thanks,
Damaeus
Ms_Squiggles - 07 Nov 2004 10:06 GMT
> Recently my headlights, dash lights, radio readouts and backlighting, dome
> light, tail lights, etc... have all begun pulsating intermittently and at a
[quoted text clipped - 19 lines]
> Thanks,
> Damaeus

Hi Damaeus,

It sounds a bit like this pulsating may be caused by the voltage regulator
on the alternator. As to the question of it actually being faulty or
not..... there are other possible causes that may be making the voltage
regulator behave this way.

Have you checked the acid level in the battery? Low level will make the
alternator alter the battery voltage by a greater amount when it starts to
push charge into it. The regulator may then be sensing the battery voltage
being a bit high, and reduce the field current to the alternator...
creating a cycle that causes the battery voltage to go between say 12 and
about 14.5 volts....

It could also be caused by the battery having some of it's plates not
functioning properly. (Either dropped off totally of sulphated up).

I suggest doing a battery test (with a proper battery tester that loads
the battery up with a hundred amps or so of load!) Followed by checking
out the voltage regulator / alternator for proper functionality.

If the voltage regulator is faulty, you can expect your battery to end up
"fried" by being overcharged. Better to spend a little time and or money
getting things checked out soon.

Pip
Backyard Mechanic - 07 Nov 2004 13:27 GMT
Ms_Squiggles opined

1. "Ms Squiggles!!!!"?   :)

But I agree!

2.  Almost certainly the voltage regulator whether or not the battery is near
gone.

If you are handy enough  to remove the alternator yourself, you might ALSO
replace the regulator yourself and save significant bucks - plus the
increased likelihood of getting a short life out of a rebuilt.

Once you have the alternator out, it's a 30 minute job MAX.. even if you
never did it before.  Note the regulator is the module that has the connector
with the smaller wires

On your car you may be able to do it without pulling the alt...I dont know

Get the regulator from parts store (suggest NAPA) to match your car/engine
type, take the alt part code too.  PLUS a replacement brush set.. might as
well change them while it's out.
   
A replacement regulator will vary in price, depending on engine/alt size,
from 48 to 75 bucks and that's an OEM mfd (Echlin) regulator.

Compare that to the price of a quality rebuilt alternator.

Alternative:   get a whole original alt from a salvage yard

If the battery is original, it's time to replace it.  At least have it load
tested.  
Damaeus - 09 Nov 2004 02:15 GMT
In news:alt.autos.ford, Ms_Squiggles <send_pdreeves_no_spam@bigpond.net.au>
posted on Sun, 07 Nov 2004 10:06:45 GMT:

> It sounds a bit like this pulsating may be caused by the voltage regulator
> on the alternator. As to the question of it actually being faulty or
> not..... there are other possible causes that may be making the voltage
> regulator behave this way.

Here's a little more information.  I sat in the car with the AC off, radio
turned all the way down and just listened while I watched the lights
flicker.  I heard a single "tap" coming from the back of the car and at the
instant I heard the tap, all pulsing of the lighting stopped.  I can't
imagine what in the trunk could have anything to do with this, but so far
I've only had this tap-stop experience once.  The next time my lights
pulsate like that, I'm going to pull over again to see if I can hear
another "tap" at the same time when the pulsating stops.  If I can, then
something in the trunk might be going bad, but I can't imagine what the
heck is back there that would cause this.  I mean, the only thing I see
back there is some speakers and a trunk lid light bulb.

Damaeus
Teknical - 09 Nov 2004 03:22 GMT
> In news:alt.autos.ford, Ms_Squiggles
> <send_pdreeves_no_spam@bigpond.net.au>
[quoted text clipped - 20 lines]
>
> Damaeus

Another thing in the trunk of that car is the Stereo system, everything but
the controls is located in the trunk.
Mortimer Schnerd, RN - 09 Nov 2004 11:06 GMT
> Another thing in the trunk of that car is the Stereo system, everything but
> the controls is located in the trunk.

And the fuel pump cutoff switch.

Signature

Mortimer Schnerd, RN

mschnerd@XXXXcarolina.rr.com
http://www.mortimerschnerd.com

putt@webtv.net - 07 Nov 2004 15:21 GMT
>headlights, dash lights, radio readouts
> and backlighting, dome light, tail lights,
> etc... have all begun pulsating
> intermittently and at a steady rhythm

Problem stems from alternator, specifically a faulty diode(s).  As long
as the thing keeps charging, no worries!  I have the same problem with
the alternator in my truck and_have_had it a long time.

Dave S(Texas)
Backyard Mechanic - 07 Nov 2004 17:11 GMT
opined in news:6709-418E3D67-234@storefull-3232.bay.webtv.net:

>>headlights, dash lights, radio readouts
>> and backlighting, dome light, tail lights,
[quoted text clipped - 6 lines]
>
> Dave S(Texas)

Sorry, that's WRONG.

And if it WAS bad diodes, the advice would still be WRONG.. bad diodes often
end up ruining the battery by undercharge or draining it.
Bob Urz - 07 Nov 2004 18:42 GMT
>  opined in news:6709-418E3D67-234@storefull-3232.bay.webtv.net:
>
[quoted text clipped - 13 lines]
> And if it WAS bad diodes, the advice would still be WRONG.. bad diodes often
> end up ruining the battery by undercharge or draining it.

Depends. A shorted diode would certainly discharge the battery or cause
a charging problem. But a OPEN diode would essentially kill a phase on
the 3 phase alternator and cause a uneven pulsation. It will still
charge, but have less output and the current pulses would be uneven.

I would be more inclined to think its a bad grounding problem if the
alternator checks out. I would pay special attention to the main engine
block ground, and any firewall grounds.

In any event, the charging system needs a full check out and you need
to move on to wires and grounds from there.

Bob
Backyard Mechanic - 09 Nov 2004 17:31 GMT
Bob Urz opined

>> Sorry, that's WRONG.
>>
[quoted text clipped - 14 lines]
>
> Bob

Well, Bob...we come out fifty-fifty on that.  You are right about the OPEN
block NOt dischaging bat...and I've seen that open phase pulsation.

Note he said pulse-tempo doesnt change with engine speed?

That points to a regulator problem,  some internal component has fried and
the reg is folding back, whether due to overcurrent and/or high battery
impedance (over voltage)...

So... bottom line, after checking all wiring and grounds - new regulator or
alt AND new battery.
BeeVee - 09 Nov 2004 23:22 GMT
> Bob Urz opined
>
[quoted text clipped - 28 lines]
> So... bottom line, after checking all wiring and grounds - new regulator or
> alt AND new battery.
Thomas Moats - 07 Nov 2004 18:21 GMT
> Recently my headlights, dash lights, radio readouts and backlighting, dome
> light, tail lights, etc... have all begun pulsating intermittently and at a
[quoted text clipped - 19 lines]
> Thanks,
> Damaeus

I'll assume turning on and off? Some where there is a short to ground and the
circuit breaker is tripping and resetting, thus the "pulsation".
 
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