OK Ive got some weird stuff going on. Tonight when in my car I stopped at a fast food place to get some stuff. I had my foot on the brake with the car in idle. Ihad the heater full blast, the radio on, and the lights on. Well the antilock light started to blink on and off, the phone turned on and off, and the lights all turned on and off repeatedly. I can only assume my battery could not provide enough juice, or the alternator is starting to go, not sure.

The battery I just bought last year, it is an Interstate,and I purposefully got one rated larger than the stock one because of the new england winters. I can recreate the problem if I brake, put full fan on, and turn on the lights.

Also since this happened the "light out" light on the console is always on, but all my lights, turn signals, etc seem to be working fine.

OK where should I start?

Thanx
87 300E

__________________
2007 Corvette Convertible Torch Red
1996 MBz SL500
2008 Harley Davidson Night Rod Special

Perhaps check witht he charging system.

Check the brushes int he alternator if it has them, and if they are very short, replace them.

Take it to you local auto store that does repairs, and have them test the charging system.

Alon

__________________
'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon

I recently had the same problem in my '84 500 sec. I also had a stumble at idle for about a week and a half before the car became possessed. I was heading home when the radio and phone turned off, then the interior lights, then a heavy chugging and finally the head lights started to dim. It was, in fact, the alternator that began to die. When at idle, the alternator can not produce enough energy to supply the car, especially with lights, brakes, heater on high, etc.. When I replaced the alternator the car was fine, smooth idle and all. All of the electrical gremlins disappeared.

As far as the light out indicator on. Did you check the license plate lightbulb? Hopefully, it is just the brushes in the alternator. Easy and cheap replacement.

__________________
J.H.
'86 300E

A lot of the systems you mention have control relays in them. if the voltage drops too low, they will toggle off and on as the voltage comes up. Kinda like a turn signal blinker. I would do a load test on the battery, and check the output voltage of the charging system with and without a load. If it drops below 13 volts with a moderate to high load, that's you problem.You ain't got enough juice Doc!!

__________________
Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.

yeah I kinda figured it was either the battery or the alternator. The only odd thing is it did this same thing last year also. Seems like it does it once per year when it gets cold. Today the car runs fine,and in fact I cannot reproduce the problem. I try to run it in idle, brake, lights, radio, and fan full blast, and the darn car runs perfectly.

I will do a load test on it tommorrow, but I bet it will come out OK. I will also replace the brushes in the alternator. How hard is this? I am pretty decent mechanically. Im assuming take the alternator out, pop it open, and just replace the brushes?

Thanx guys, the best 2 things I have ever bought for my car are my remote starter and my batter buddy (keeps enough juice for one start).

__________________
2007 Corvette Convertible Torch Red
1996 MBz SL500
2008 Harley Davidson Night Rod Special

Just take the voltage regulator that is in the back of the alternator held in place by two screws. Just take the screws out, if the brushes are short, put a new one in. You are done. No need to take the alternator out. PartsShop should have it.

__________________
J.H.
'86 300E

Besides not charging properly, can running the car with short brushes in the alternator damage anything? It is winter here and I am going to try to wait till the spring.

Also how do I know if they are short? I have no idea what they look like full length.

Thanx

__________________
2007 Corvette Convertible Torch Red
1996 MBz SL500
2008 Harley Davidson Night Rod Special

The carbon brushes that transfer the current to the slip rings on the alternator should be 1/4 inch or longer.
Not replacing them will not damage the alternator, it just won't work. I drove from Alaska to PA with worn out brushes and never hurt the alternator on my 300SD.
P E H

I got a good Battery charger at Wal-Mart for abort $40. More expensive ones are higher capacitie and are not needed for a trickle charge. They are also a lot heavier.
I am still using one I built myself almost 40 years ago out of computer power supply parts. It is actually a variable 0-14 volt DC power supply so I can charge at any rate I want.

P E H

Doc, get it fixed now. The winter is hell on electrrical systems, cold starting, defrost, etc., etc. You will get stuck when you least want or expect it to happen. At least do the brushes/regulator. Takes about 10-15 minutes.

__________________
Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.

One thing to note is that with those new optima spiral cell batteries, you don't want to charge them with a charger at all. this is what I have been told by my optima dealer.

The recommend you jump the battery with another for a few seconds. once the car is started, the battery will recharge on its won back to normal power levels.

IF your alternator is faulty, definately check the brushes and replace them. I can tell you that it sucks to get stranded at night with a broken alternator. its happened to me in every car I have owned. once I was a block away from my house. Even a jump start and attempt to drive was useless. the fuel pump would shut off if there was not enough power.

I have no had my alternator stup functioning on my benz yet. My father just had an alternator rebuilt and made more powerful. It cost him over $400 but it went from a a lowly 65 amp to a massive 170 amp. His optima battery will be back to full charge after about 20 minutes with that alternator on it.

Alon

__________________
'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon

How does an optica battery know what is charging it? Electrons are electrons whether they come from a battery charger alternator or generator.

P E H

PEH I have no idea. I am just relaying what the optima battery guy said to me about charging it. He said they are a different cell technology and charging it could ruin the battery.

But the jump and charge proof is there. My fathers car had been sitting for a few weeks he was out of town, and the battery died. We hooked up the jumper cables, both cars off. The car started instantly with a very short time between when we hooked it up and when it started. It was bone dead. No click from the starter even. and a few seconds of juice and the battery had enough to start the car. Needless to say the car has not had a baterry problem, until he of course leaves town for a few weeks. Then it'll die again. - He's got an alarm that is wired into the whole car, fuel door, windows, sunroof, starting, radio, and doors.

That alarm drains the car, but then again the car is quite old, and it runs on its electrical system. Not to mention that he always has AC and the stereo on. all of which put a heavy load on the car. Even the alternator can't help with that, but he can now drive the car at night with AC and stereo on, without the car dying on him.

In anycase enought about his charging issues. I just thought I would relay the info. you are more than welcome to correct me if I am wrong. I just thought it would be some good info to relay from my battery guy in the case of optima style batteries. If he is wrong then by all means correct me. I would think he knows since he does work with optima batteries all the time.

Alon

__________________
'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon

Is your optica battery guy a salesman? If he is, that might explain it. Most salesman don't know diddlysquat (I wander what spell check will come with up for this word) about technical issues. Just ask a car salesman some technical questions about a car he is selling to prove my point.

When the voltage from the alternator, battery charger or any other DC source is the higher than the voltage of the battery, the current will flow into the battery and it will charge. If the voltage of the source is lower than the battery voltage the current will flow out of the battery and the battery will discharge unless the current is not reversible such as in a battery charger. In the old generator systems, the generator had to be protected from battery current flowing back thru it. This was done by a "mechanical diode" in the voltage regulator box. This doesn't happen with alternators because there are solid state diodes in the alternator which prevent reverse current flow.
P E H