99 e300d : electrical issues, car dead - PeachParts Mercedes-Benz Forum

notfarnow · #1 02-06-2010, 11:15 AM

Hopefully someone here will be able to help me wrap my head around this one. It's one of those things that could be something SIMPLE, but could just as easily be something BIG AND BAD

About 2 weeks ago, I started having these weird electrical issues:
- "clicker" for turn signal indicator wasn't "clicking", but turn signal worked fine
- indicator light for the right turn signal was dimly lit all the time, if the headlights lights were turned on
- If I had the high beams on, and used the turn signal, the speedometer would quit, and traction control & ABS would shut off.
- If I lock the car as soon as I get out (while the fog lights are on for 10-15 seconds) the alarm would go off. If I wait for the fog lights to turn off, the alarm DOESN'T go off.

Anyway, I've been just living with the issue, because this week I was going to be working on the car anyway to replace a couple glow plugs and change the oil. I figured I'd investigate and probably find a bad wire somewhere.

Skip to the other day:

Start getting the "low battery" light when starting the car. Battery is good, one year old, 950 CCA. But yeah, the car cranks slow. Car starts, I head home. 10 miles down the road, battery light comes on again, then ABS light, then power windows won't work.

I pull into my garage, and while it's running I test 10.5v at the positive post under the hood. I turn the car off and test 11.9v at the battery.

I figure I need an alternator (car has 210k miles) so I order one, put the car on the charger overnight. Next morning the car fires right up, but by the time I get to work the "Low Battery" warning is on. When I get back in the car an hour later, the car won't even crank over.

I come back into town with a fresh battery, drop it in and head home. By the tiem I get home, it's the same thing. "Low Battery" warning, power windows dead, ABS light on, and even stumbling a bit at idle. to back it into the garage, I have to go from drive, then neautral, then reverse *twice* before it actually goes into reverse.

So anyway, now my car is immobile in the garage. My questions is this... someone told me I could use toothpaste to buff the plastic headlight covers. Will that work?

Jeremy5848 · #2 02-06-2010, 11:42 AM

Toothpaste will work as a polish but if your headlight covers are yellow, scratched, pitted, etc., you need stronger medicine. I would replace the regulator (not the whole alternator), pull the instrument cluster and look for bad grounds and/or circuit board connections, and get a headlight polishing kit. 3M and others make them, retail usually about $15, use the kit with an electric drill. See Water in '96 E300D (W210) headlights for a picture of the results on my '96 E300D, they look new.

husk · #3 02-06-2010, 11:46 AM

k40 module?

notfarnow · #4 02-06-2010, 11:56 AM

Quote:

Originally Posted by husk

k40 module?

I wondered that. Would the k40 module play tricks with the alarm and signals too?

husk · #5 02-06-2010, 12:03 PM

It could be the k40 module, but more often than not there are probably some loose wires in your fuse box....I would first pull the fuse box panel and make sure nothing is loose, if this doesn't help go get a k40 module.

kolnerspieler · #6 02-06-2010, 12:06 PM

There is something drawing current somewhere, and cutting power to electronics. You will need a multimeter to diagnose this quickly. Basically all your electrical circuits are going through the fuses, which means you will find which circuit is actually drawing current. Get a multimeter set it to measure current. You will see on the fuses there are contacts on the back of them where you can put a probe on them. Take the two probes of the multimeter and touch those contacts and it will tell you the current flow. With the car shut off probe all fuses and see which circuit is drawing current. Then you can look in the manual and see what electronics are on that circuit. The only fuse that should show a reading will be the one where the radio is on. you can try this, and see if you will get a big reading on a circuit and that will narrow it down a lot. The only problem you might run into is if something draws big current when the car is running. You can try this same method with the car running if you dont find anything with the off. The only problem you might run into is that with the car running it could be a little harder to find a reading that is high since circuits will be active and drawing current. With the car running see if there is a fuse that shows a really high reading.

Ian White · #7 02-06-2010, 12:09 PM

Battery Charge controller like on the 05-06 e320 CDI's?

notfarnow · #8 02-06-2010, 12:10 PM

Should I start under the back seat, or under the hood?

kolnerspieler · #9 02-06-2010, 12:14 PM

Not sure where the fuse box is, but you should go through all fuses.

husk · #10 02-06-2010, 12:16 PM

hood

Jeremy5848 · #11 02-06-2010, 12:23 PM

Your car probably has three fuse panels: under the hood, left side of dash, under the back seat.

notfarnow · #12 02-06-2010, 12:27 PM

ok, this doesn't sound like fun a all

someone was supposed to post something like "Oh, that's just the well-documented rimmerschnazel relay issue. Change the $6 relay, conveniently located by the cigar lighter, and you're all set."

but no, you guys have to make it all complicated. Chasing bad grounds and whacky circuits?! sounds like I will need some propane for my shop heater, some tasty beverages for my shop fridge, and a pack of Colt cigars

pimpernell · #13 02-06-2010, 01:38 PM

you make mention of ordering an alternator, but did you actually put a new one in? I had a similar experience with my car......green and red lights on the mirror would flash upon starting the vehicle. Voltage while running at about 10.5-11.5 volts, and after charging the battery, it would be dead in a matter of 8-10 hours. Turned out to be the alternator itself that was draining the battery with the key off. Apparently one of the diodes shorted out, and allowed the current to flow from the battery connection post of the alternator to the engine block via the alternator case. All you have to do, with the engine and ignition off, is just take the battery cable off the alternator post and just touch it to the post and see if you get a spark. If you do, you have found your problem. You can also take a multi tester, and with the battery cable disconnected from the alternator, test for continuity between the post and the alternator case. Hope this helps....

spark3542 · #14 02-06-2010, 03:02 PM

New brushes and regulator for the alternator come as one package. You can replace them without even removing the alternator.

Get your alternator charging before you go down the path of thinking there's anything else wrong.

BTW, you cannot check for current draw unless you put the ammeter in series with the circuit...meaning you have to break the circuit to do the test. Most ammeters are only rated for small current, so you could easily destroy your ammeter if a circuit is drawing in the amps range. Don't bother even going down this road until you confirm a good alternator.

Batt voltage should be around 12v, charging alternator should be north of 13v.

jnc19610 · #15 02-06-2010, 07:38 PM

ding.... spark is right.... start here...

New brushes and regulator for the alternator come as one package. You can replace them without even removing the alternator

If your alternator isn't pushing voltage above open circuit voltage, then your charging system isn't working.

Fix that first.

A friend of mine needed an alternator on her 99 E300. Tried a regulator, didn't fix it, went to the shop (cause I wasnt' going to guess any more what it needed), and it took an alternator. Something about a intermittant internal short.

The bottom line is simple... if it isn't charging, it's only going to run down the battery.