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#1
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1989 300E light problems
I have a 1989 300E. The problem I am having is when I am driving at night I turn my lights on and they work fine but I noticed that the lights go bright then dim then bright again. This is not only the head lights but the interior lights also.
What could be the problem? Thanks Fab |
#2
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Most likely an alternator/charging problem.
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MERCEDES Benz Master Guild Technician (6 TIMES) ASE Master Technician Mercedes Benz Star Technician (2 times) 44 years foreign automotive repair 27 Years M.B. Shop foreman (dealer) MB technical information Specialist (15 years) 190E 2.3 16V ITS SCCA race car (sold) 1986 190E 2.3 16V 2.5 (sold) Retired Moderator |
#3
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How do I test the alternator?
Thanks Fab |
#4
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Could this also be caused by my serp belt slipping?
Thanks |
#5
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i have the same problem with my 87 300e and its probably a weak/bad alternator, ive never had a charging problem so i ignore it (i know the little battery icon light works on my car) it could also be something with the voltage regulator but its hard to tell without swapping out for another one. i would think v belt slippage would manifest in other ways long before being able to cause a problem like this. do the belts squeal loudly even when the car has warmed up? some nice battery chargers have the option to test alternator and your local parts store will probably do the same for free (still haven't learned how to use my multi meter but im sure it would test it too) hope this helps!!
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E30 B25 126.036 123.130 with 616-Frankenbenz (sold) 124.030-Greyhound (sold) 124.030-Schnauzer (sold) DERP DERP |
#6
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300e lights go dim
Although the dimming lights would seem to be evidence enough of a problem with the charging (alternator) system, try this test that my F-car mechanic taught to me.
Go down to your local RV supply house and buy one of those plug-into-your-cigarette lighter, digital voltmeters. I say your local RV place because they seem to be the cheapest place to buy these things. Should be around $10. Plug it into your cig lighter with the car powered up, but with the starter NOT engaged. You should have a reading of just over 12 volts. Start the car and with the car in idle, you should have a reading of between 13.2 and 13.9, but not over. Drive around town and keep track of the readouts, especially when the lights go dim. Check it again when you turn off the engine. Readings that don't go over 12 when the car is running would be a problem with the alternator. If they read in the 13 range when running but less than 12 with the engine off would seem to indicate a problem with the battery. Let us know what you find.
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03 CLK430 Cabrio 211K Pweter Silver/ Oyster Leather 90 300SEL 214k Pearl Black/ Alto Grey/Black Leather Prior: 85 190E, 88 300TE, 89 300TE, 90 300E 2.6, 90 300TE, 92 300E 2.6, 91 and 93 300SL, 87 Ferrari Mondial Cabrio |
#7
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I will try this out on the weekend and post my results.
Thanks, Fab |
#8
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typically a 25 dollar voltage regulator fixes the issue
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1989 300ce 129k ( facelifted front,updated tail lights, lowered suspension,bilstein sports, lorinser front spoiler, MOMO steering wheel, remus exhaust,stainless steel brake lines). (Gone) 1997 s320 154k (what a ride). Sold with 179k miles. Replaced with Hyundai Equus 1994 e320 Cabriolet 108k ![]() 1972 280se 4.5 153k Owned for 12 yrs, sorry I sold it [/SIGPIC] |
#9
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I finally checked out what voltage my car is putting out when I am driving the car.
When the engine is off the voltage reads 13.25 volts When the lights are dim the voltage reads 13.22 - 13.61 volts (this is when the car is on and driving) When the lights on my car are at their brightest the voltage reads 17.77 - 18.02 volts (this is also while driving) Now to me this would be the voltage regulator. The cheapest I could find was $75.00. The dealer wanted $96.00. So before I buy it I wanted to make sure that this was the problem or do I need to change the whole alternator. Thanks Fab Last edited by 300ESUPER; 12-23-2006 at 02:54 PM. |
#10
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Can anyone out there help?????
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#11
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Super,
This is from experience on a much less sophisticated vehicle, but I'm going to throw it out there and hopefully get some interest flowing: First, 18v -period- sounds too high to me. My experience started with a bad battery (stored and sulfated) that was no longer accepting a full charge (voltage ok), so that my electrical system was all but running directly off of the generator (yes generator), which messed up the voltage regulator (overworked) multiple times (as well as a stereo aplifier x 2). My only point would be to make sure and check out the condition of your battery if you don't know already for sure, as to prevent going round-and-round as I did. It's that 18volts that makes me think that this may be a possibility. Scotz |
#12
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Thanks for the reply ScotzBenz. The battery is only a year old and when I put my volt meter to it, it was well over 12V. Is there another way to test the battery?
Thanks Fab |
#13
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Check price of voltage regulator here at Fast Lane.
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Earl ![]() 1993 190E 2.3 2000 Toyota 4x4 Tundra |
#14
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The voltage regulator is a 5 minute job...
Click on "buy parts" on top of this page. Two screws an you are done...
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J.H. '86 300E |
#15
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Unfortunatlly fastlane does not ship to canada.
Thanks |
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