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  #1  
Old 07-12-2009, 11:55 PM
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Lights On = Loss Of Power

Hi Everyone,

When I turn my lights on I can feel the car losing power.

Last night I drove home and noticed that when I was accelerating from a stop I had little to no power. After a bit then the car would accelerate and off we'd go. A couple of times while I was driving I would lose power but then it would correct.

Today it drove perfectly, no problems. Then I turned on my lights (while I was moving forward) and felt the car quickly losing power. I immediately turned the lights off and everything went back to normal.

A couple of days ago the "check lights" message came on when I start the car (even without the headlights on).

It's a 1999 e300 TD, about 128K miles, new transmission @ 114k.

What is going on? Any ideas?

Thanks,
Christy

p.s. I searched the archives but was not successful in finding anything

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  #2  
Old 07-13-2009, 01:53 AM
compress ignite's Avatar
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Location: 32(degrees) North by 81(degrees) West
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Alternator ?

The Battery is just a Storage device for "Stray" Electrons (Humor)

One of the larger drains is the headlights,and if your Alternator were ill
the Headlights "Draw" might lower onboard power enough to affect/effect
all the fancy computerized engine controls.(Low Voltages do funny things)

Since your diagnostics are already 'hollerin about the Headlights I'd start there.
(I know Nothing about Headlights...To me it's a Bulb that's either
Good or Bad)Try the simple Voltage test outlined a couple of lines below.

Worn brushes in the Alternator's Voltage Regulator will cause erratic power.

Of Course there could be something wrong with your Headlight system,causing
it to pull more power than it should.A Bad Ground wire for the Headlights
will play havoc.

First inexpensive test would be to see what the Voltage output of the
Alternator is with the engine running...Multi-Meter leads on the Battery
posts,with engine idling,'Should be between 13 and 14.1 volts.

Then turn the Headlights on and see how much difference in Voltage.
If the Voltage drops below 12 that may be your problem.

There is also something called Amperage,BUT you have to have a DC clamp
meter to test that.

I'd suggest one of the Big auto chain stores...They'll all test your Alternator
output for free...BUT, Too Many Electronic Wonders under your hood for them
to Accidentally fool with.

Inexpensive Multi-Meters to be had at Harbor Freight and Sears
(less than $20.00 on sale)

WAI is a big Wholesale only electric parts distributor to the rebuilding trade.
(BUT you can see parts available for your Alternator)
http://www.wai-wetherill.com/products/sresult1bom.cfm?ManufName=BOSCH&item=0-123-320-046

This is the Voltage Regulator ,with Brushes for your Alternator.
http://www.wai-wetherill.com/products/partimage.cfm?wai_num=IB387-1
"D+" and "FLD" are the Brushes.
They also offer just the brushes:
http://www.wai-wetherill.com/products/partimage.cfm?wai_num=38-91800

#430 in the Cyrillic Pictograms is the Voltage Regulator.
Attached Thumbnails
Lights On = Loss Of Power-screenhunter_04-jul.-13-02.02.gif   Lights On = Loss Of Power-screenhunter_05-jul.-13-02.14.gif   Lights On = Loss Of Power-screenhunter_06-jul.-13-02.18.gif   Lights On = Loss Of Power-screenhunter_07-jul.-13-02.19.jpg  
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Last edited by compress ignite; 07-13-2009 at 02:24 AM.
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  #3  
Old 07-13-2009, 02:53 PM
compress ignite's Avatar
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An Evil Relay for Each Chassis

In W124 circles the OVP (Over Voltage Protection Relay) is the Evildoer.

I just remembered the W210 has a K40 relay that when feeling ill presents as
all kinds of things that it's not.

SA @ RBM in Atlanta said it's possible to see this kind of Symptomology with a
flaky K40 (The Only way to tell for sure is to hook it up to the STAR machine
@$110.00 USD)(Do Techs not use Digital Multi-Meters ? Silly Me,Not when
the Almighty STAR diagnostic machine can clip your pocketbook/wallet for $110.00 !)
I have to be fair,it's probably $110.00 just to have a R.O. written no matter what.

BUT he agreed that the Voltage test of the Alternator would
tell you if it's the Alternator[and/or It's Voltage Regulator].
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  #4  
Old 07-13-2009, 03:15 PM
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I stopped by the mechanic today and he was totally puzzled.

So, we started where the problem began with the "lamp defective" warning.

He said it was my left brake light so I popped my trunk and he fixed it.

I turned the car off and then back on. Then I turned on the lights and accelerated - NO loss of power!!

I drove home with my lights on to see if it was an anomaly. It drove home fine. I stopped at 9 lights and nothing.

He can't believe that the two are related and neither can I but so far so good.

I'll update if there are any changes.

Thank you so much for your input thus far. If it happens again I will share what you have written with my mechanic.

Thanks Again!

Last edited by christyb; 07-13-2009 at 07:08 PM.
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  #5  
Old 07-13-2009, 04:29 PM
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Whooooooooooooooo...ooooooh !

"Brakelight Bulb Fixes Performance Problem" (Video @ 11:00 P.M.)

Mayhaps, It's time for you to purchase a Lottery Ticket or Three (Only a "Buck")
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  #6  
Old 07-13-2009, 04:42 PM
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Are the new diesels different from the old ones in terms of affect of electrical systems on the engine performance. Mine doesn't give a crap if there's even a battery in there, once she's running.
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Old 07-13-2009, 04:53 PM
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Quote:
Originally Posted by ::matthew View Post
Are the new diesels different from the old ones in terms of affect of electrical systems on the engine performance. Mine doesn't give a crap if there's even a battery in there, once she's running.
yeah but yours is mechanical
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  #8  
Old 07-13-2009, 05:08 PM
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Quote:
Originally Posted by compress ignite View Post
"Brakelight Bulb Fixes Performance Problem" (Video @ 11:00 P.M.)

Mayhaps, It's time for you to purchase a Lottery Ticket or Three (Only a "Buck")
The lottery ticket will be cheaper than my bill (which was nada) for the "repair"!

It wasn't even a new bulb, he just tightened it up.

I know it makes NO sense. And yes, I'm sure you are especially suspicious of my description of the issue since I am of the "womenfolk" persuasion but I promise you, there was a definite loss of power - it was scary in intersections especially.

I will go buy some lottery tickets tonight in honor of this occasion!

Thanks,
Christy

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