W210 E300d "Battery Charge" light on at start and shutdown - PeachParts Mercedes-Benz Forum

satyr · #1 02-27-2013, 05:16 PM

Hey all,
I searched the forum (and 3 others) for several days now and I'm unable to find any posts that would apply to my situation and I've ruled out or tried all of the other solutions. So, I've started a new thread and appreciate any help you could offer on this.

This thread is related to this one- regarding installation of a new alternator and etc.:
http://www.peachparts.com/shopforum/tech-help/334142-143a-alternator-96-s420-96-e300.html

The original problem began a couple of months ago when I had a "no start" one morning. I put the battery on a trickle charger to get it charged and started, but saw that that the voltage in the climate control display would not get above 12.1-12.5 volts while driving, and the battery didn't get above low 12 volts. I had to leave it on the trickle charger in battery tending mode just to drive it every week or so. So, before changing parts, I removed the rear seat and hooked up a multimeter to the battery and watched the voltage when starting the car- glowing the plugs dropped the voltage at the battery to 11.5 or less. Cranking the starter dropped it even more- even down into the high 10s. After it started the voltage would stay in the low 11s or high 10s while the glows were running, but after they cut out, it still wasn't charging the battery because the voltage stayed in the low 12v range at the battery. I always noticed that the dome lights and headlights had been somewhat dim since we bought the car.

So, after researching similar problems, and taking the battery in for testing several times and being told it was "good, needs charging" I let the store rapid charge the battery and embarked on the journey to clean all of the ground straps, and replace the big un. More on that here with pics:
http://www.peachparts.com/shopforum/diesel-discussion/334316-w210-ground-strap-location.html

The car now has bright, shiny, tight and squeaky clean ground straps and wires including the one at the passenger side of the rear seat for the battery and a new one at the bell housing to chassis. The car has a brand new 143a alternator that is giving 13+ to 14v on the climate control at 2000-3000 rpm. The battery was even replaced with another one from Advance. (It has an advance battery because last year when it had a "fail to start" and was towed to the shop from the gas station where it died, it was the only local battery they could find for the car. Battery replacement seemed to fix the issue- at least until this same problem appeared 1.5 yrs later as referred to earlier. This "new" battery is wearing a build date sticker of 4/2012)

There is also a brand new serpentine belt and all pulleys are completely clean. There is absolutely no belt squeal.

Prior to cleaning the ground straps, and replacing the alternator with a brand new 143a model, it never gave any sort of "battery charge" light or anything. Now, after all of this (clean grounds, clean pulleys, new serp belt, new alternator, new battery) I'm getting a red "battery charge" display and beep after the glow plugs are glowed, immediately after cranking the starter (which fires right up). After resetting the battery charge light- it stays off the entire time I am driving around. And, as stated earlier- the climate display is showing 13+ to 14volts while driving after the gp's cut out. When I park it and shut it down- the "battery charge" displays again with a "beep." I just went out to the garage and checked the battery voltage at the post under the hood and after sitting for 3 days it's at 12.52 volts. After parking it 3 days ago the battery was at 12.6volts.

Is this symptomatic of another defective battery? Is this a bad positive battery cable? (connectors at both ends are perfectly clean.) The system voltage on the climate control is fine- what could this be? Gaaaaaahhhh!

Any help is appreciated! Thanks- John

Jeremy5848 · #2 02-28-2013, 12:58 AM

What year is your car?

The return of the battery charge light and beep when you turn off the engine is normal -- it is a reminder that you had (and cleared) a problem earlier. It does not mean a second occurrence of the problem. The battery voltage measurement is reasonable given that the W210 draws a little current from the battery (for the alarm and some other circuits) even when the car is off.

An experiment you might try is to shut off the car and disconnect the battery, check the battery voltage and leave the car for a couple of days, then check again. The battery voltage should stay close to where it was when you disconnected it.

"After the glow plugs are glowed" -- "Immediately after cranking" means that the engine is still in afterglow (if the engine is cold -- you don't say). Afterglow time varies from as low as zero to as much as 3 minutes in your car. With a hot engine there is no afterglow. Any difference in your problem?

Jeremy

satyr · #3 02-28-2013, 01:14 AM

So, I couldn't stand it anymore, and went and pulled the battery out of the suburban and yanked the rear seat out AGAIN- and swapped the suburban battery in. I got the EXACT same result, keyed on- no problem and glowed plugs.

Before glowing the gp's the battery read 12.58 at the multimeter at the battery, and 12.1 in the climate display.

Glowed the gp's and the display dropped to 10.8 and the multimeter read 11.62 at the battery.

Cranked the starter- immediately got "battery charge" light on the dash, voltage dropped to 10.5-10.7 on the climate display and battery dropped to around 11.7v.

Let it run for a few seconds with no change- revved to 2500 rpm and climate display went to 13.0 and the reading at the battery was 13.75.

GP's cut out and at 2000 rpm the climate display said 13.5v and the reading at the battery was 14.23.

I let her run for around 5- 10 mins, and then shut it down- as I keyed off- I got "battery charge" light on the dash again.

I restarted and got nearly the exact same results, "battery charge" on the dash and all, but reduced voltage only lasted a few seconds- maybe because engine was warm? But, should the voltage be dropping so much when she glows and cranks? And would that cause the "battery charge" on the dash when the starter cranks AND when the car is shut down? The gp's are about a year old- bosches- could all of this be a gp relay problem? Is there a ground for the gp relay I missed that would cause this? Or is this something that is stuck in the computer and it just keeps regurgitating it until it is cleared out by the stealer?

Sorry Jeremy- was typing as you posted. The car is a 96, and this happens regardless of whether the engine is hot or not- although the lower voltage after cranking is much shorter after it has warmed up.

Please let me know what y'all think! Thanks again- John

Jeremy5848 · #4 02-28-2013, 08:57 PM

The warning at shutdown is just a repeat of the first one -- the computer is programmed to remind you of the problem you had when the engine was started. It does that so you won't forget to address the problem.

The voltages you have measured look reasonable. Pre-glow, cranking, and after-glow will all pull the battery down. Your big alternator should do better, however, at recovering, than the original 90 Amp alternator. I have only a 115 Amp alternator in my '95 E300 (same engine, less electronic) and it recovers almost immediately after starting. That is hard to judge from a written description; your car may actually be OK. The problem could actually be in the computer itself. Where in the car this is I do not know.

Experiment: with the engine at least warm if not hot, unplug the primary (4-wire) connector at the pre-glow relay so that it cannot operate. Start the engine, watch the voltage, see if you still get a battery light. You may get a code because of the disconnected pre-glow relay, ignore that. Report results.

BTW, do you have a code reader to plug into the OBD-II port in the driver's under-dash panel? It would be interesting to see if this battery warning is also throwing a code.

Jeremy

vstech · #5 02-28-2013, 09:47 PM

12.58 is not a fully charged battery. it's only 80% charged, you may have a damaged battery after running low so much. the alternator sounds like it's working great. I think you now need a new battery!

satyr · #6 03-01-2013, 12:38 AM

Quote:

Originally Posted by vstech

12.58 is not a fully charged battery. it's only 80% charged, you may have a damaged battery after running low so much. the alternator sounds like it's working great. I think you now need a new battery!

Ack! OK, so here's what I'm gonna do tomorrow. I'm putting the group 49 on the big charger tomorrow. Then I'm sticking it in the 300 to see what it'll do...

satyr · #7 03-12-2013, 02:24 PM

So... After trickle-charging the group 49 battery on the automatic charger, I got a max of 12.6 volts after taking it off the charger and allowing it to sit for 4 hours. I hooked it up and she glowed (voltage dropped to 10.6- 10.8 on the climate control display) and she cranked and fired up perfectly. I got the same "battery charge" light as usual. Voltage stayed around 12.7 on the climate display until I gave it 2000 rpms and it raised to 13.5. At the battery- after the glow plugs cut out- it went to 14.25. I drove it for an hour- and the voltage on the climate control stayed at 13.5-13.7 the entire time. When I shut it off- the battery charge light reminder comes on. So, I'm at a complete loss. The only thing I can think of is that I'm either missing something somewhere, or the battery charge light is something that has to be cleared by the dealer thru the ecu...

vstech · #8 03-12-2013, 03:20 PM

odd.

I think you should take your car to a McParts store and have an on car alternator check done. they'll also check the battery capacity.

satyr · #9 03-27-2013, 04:28 PM

So, today I got to thinking about something I had read in another post about an alternator problem, and went to check out the D+ BLUE WIRE. I attached my multimeter to the blue D+ wire with an alligator clip lead and with the key off and I have nothing, zilch- which is what it's supposed to be, I think.

But when I key ON with glow plugs glowing- I've only got 1.8 VOLTS at the BLUE D+ WIRE. When I start the car- I've still only got 1.8 volts at the D+ blue wire.

That clearly isn't enough to "excite" the alternator- (if it needs to see 0.5v less than system voltage like was described in other posts) so... Now what? I followed the cable back to underneath the air cleaner box- but didn't have time to follow it back from that point. I have no clue what else is in the circuit on the w210 to check. Is this a K40 relay issue? Is there a fuse or a corroded connection that could be at fault? Any suggestions are appreciated! -John

Zulfiqar · #10 03-27-2013, 04:33 PM

use a junk fish bulb holder and use the bulb in series and touch the D+ on the alternator and the battery positive - measure voltage, your alternator should be working normally.

satyr · #11 03-27-2013, 04:51 PM

Would wiring a 12v bulb between the B+ and D+ "wake up" or excite the alternator somehow?

satyr · #12 03-27-2013, 07:38 PM

So- I pulled the blue D+ wire off of the alternator, hooked it to the multimeter with an alligator clip and had my "helper" turn the key to the "on" position. I got nothing. Curiously, I also didn't get any idiot light for battery or alternator on the dash either. Grounding it didn't result in any lights either... (I haven't tried running the bulb-jumper yet Zulfigar, because I thought I would check this first, but that's next if I don't get the D+ wire issue figured out.)

It is possible that the wire is broken inside of the blue insulation- but does anyone know if there is a relay or a fuse anywhere for the D+ blue wire that could be blown? I checked the under hood, driver's side dash, and under rear seat locations for blown fuses and everything checks out fine...

pmckechnie · #13 03-28-2013, 08:50 AM

We need to talk about the blue wire and what it does and how it should work. With the key off, you should see nothing on the blue wire. You are good there. With the key on but the engine not running you should see a very low voltage. 1.8 volts is fine. This small voltage only tells the regulator that the key is on and it holds this voltage low to keep the light on. You are good there. Once the engine is running and the alternator is charging, the regulator puts charging voltage on the blue wire which will turn the light off because it has voltage on both sides of the bulb and no ground. That is not good in your case, however the alternator is charging. So, it looks like our regulator is bad. Also just for your information, after the alternator is charging, it doesn't need the blue wire at all. You can unhook the blue wire after the engine is started and the alternator will continue to charge until the engine stops. So the blue wire only informs the regulator that it needs to turn on the system. It doesn't excite the alternator, It turns on the regulator but can not turn it off. I would like to see a test done with a test light with the clip hooked to battery voltage and the probe hooked where the blue wire hooks, with the blue wire disconnected. The test light should come on. Then start the car and see of it is charging and the test light should go off. What I have done for years is disconnect the blue wire. Start the engine and then touch the test light to the terminal. You should hear the engine change sounds as the alternator starts charging and the test light should be off. A test light with an led light may or may not work. They don't pass the amperage needed to turn the regulator on.

I know this is a long boring post, but It helps to know how something works before you trouble shoot.

Zulfiqar · #14 03-28-2013, 09:31 AM

You are exactly correct for the bosch 2 wire alternator testing. I had a VW Golf whose blue wire broke somewhere near the battery - and I was going to a dinner party - I used my 12V lamp tester to start the alternator and it made it to and back with no problems at all.

The blue wire should have switched power and in some cars there is a resistor in parallel to start the alternator if the bulb is blown. When the alternator is off the regulator outs ground to switch on the warning light, It goes to +ve when it starts.

Jeremy5848 · #15 03-28-2013, 11:38 AM

Quote:

Originally Posted by pmckechnie

Also just for your information, after the alternator is charging, it doesn't need the blue wire at all. You can unhook the blue wire after the engine is started and the alternator will continue to charge until the engine stops. So the blue wire only informs the regulator that it needs to turn on the system. It doesn't excite the alternator, It turns on the regulator but can not turn it off.

You are correct except that the alternator does need to be excited. The initial current is provided by the circuit that includes the battery, charge indicator lamp, and associated wiring. Once the alternator is running, it "self excites" and no longer needs current from the blue wire. As you write, the blue wire is then no longer needed.

Jeremy