e30 charging problem...

I have a charging problem with an '89 e30 ix.... battery light stays off, voltage while the car is running is a bit less than battery voltage...
Here's what I've done so far:
Replaced regulator (actually 2 of them).. bench tested alternator (load & no load)...the guy was an auto electric guy.. rebuilds alternators. checked all fuses.. were fine checked voltage with the car off at the alternator on main + lead and alternator body.. was close to battery voltage
at that point I thought maybe the alternator wasn't getting voltage on the blue wire to establish field...so I took the inst. cluster off and...
tested resistance between blue wire and cluster pin (forgot which one... came from an apparently misprinted bentley book that has the rows for the pin numbering wrong)... tested voltage on various inst. cluster pins according to bentley, all were fine.. made sure the leads on the ignition switch were good
then thought maybe the inst. cluster wasn't doing whatever it needs to do to power that blue wire to the alternator, so I replaced it (the cluster) -- (it was acting flaky anyway... fuel guage was jumping..etc)..
that didn't help.. (fuel guage looks better though!)
So I'm starting to feel some defeat... does anyone have any other ideas? Are there any relays that might be broken? Any help would be appreciated... I'm considering calling Duracell to see if they cell high capacity, disposable, 12v batterys! :)
Thanks in advance for any help!
-Aaron
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Check the warning light bulb and wiring. On many cars this supplies the field exciting volts. If it's not on with the engine stopped it's the first thing to check.
--
*Puritanism: The haunting fear that someone, somewhere may be happy.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 2006-09-23 14:25:13 -0500, "Dave Plowman (News)"

I thought about that... but according to Bentley they put a resister in parallel with the light in case the bulb goes... could still be the wiring though I suppose... but that's all in the instrument cluster replaced...
I'll double check and make sure the bulb is lit before the car is started and report back...
-Aaron
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

If you've replaced the cluster and the bulb still doesn't work, this points to a wiring fault. Two blown bulbs are a little too much of a coincidence. If you have the wiring diagram, you could provide a temporary ground or +12 volts (whichever it is) to the warning light terminal on the alternator. If it starts charging you've got it.

--
*Everybody lies, but it doesn't matter since nobody listens*

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 2006-09-23 20:05:32 -0500, "Dave Plowman (News)"

Well, sure enough the battery light wasn't lighting up. I reread some of the bentley troubleshooting steps and found something that I somehow completely missed before. They suggest removing the d+ (blue) wire from the alternator, turning on the ignition, and connecting it to ground. If the battery warning light lights up, all is well in the inst. cluster department, and it's something internal to the alternator.
The light lit up...
The real bitch of it is that I actually read Matt's prior thread quite a while ago (before bringing the alternator to the shop)... so I was wary of this whole bench-testing thing... When the guy tested it, I was completely satisified that there wasn't anything he could have done better. He loaded it up to like 30A, he ran it unloaded, everything checked out.
*sigh*
Thanks for all your help - I'll let you know what happends after I bring the alt. to the shop...
-Aaron
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
T'was the stator. The alternator guy says that Bosch stators have a thing with corrosion -- rust builts up in the fins on the stator and spread the fins out, and can short it with the wiring. So he replaced the stator and the bearings for $100.
Thanks again for your help!

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

The voltage at the battery with the engine on should be around 14 volts. If this condition does not exist, your battery will not be charged.
You said that the voltage at the battery with the engine on was less than 12 volts. This is a clear indication that there is a problem in the charging circuitry.
A likely cause is a bad regulator, but you said that that you replaced it. It is most unlikely that two regulators would fail. Another likely cause is a problem with the alternator, but you said that someone checked it.
The light goes off when the alternator voltage is higher than battery voltage. This indicates that the alternator is working fine. By the way , that light and the resistor you mentioned is the only place in the instrument cluster which affects your problem.
There is a direct connection between the battery and alternator because the current is much too high to travel any path but the shortest. I suppose you did notice that the battery cable is much bigger than those in the instrument cluster.
Hence, I would check all of the connections and all of the battery to alternator cables. Jim
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Well, I don't know if it is any help but I had a similar problem on my '91 a while back (Bench tesed fine in all conditions, warning light did not indicate fault, but yet the battery clearly died when the car was driven), but a regulator fixed the problem... and I suspect that the brushes were the only problem with it. All that to say that just 'cuz the alternator checks out doesn't mean it's good... really makes me wonder why bench test them, but that's a different question.
On a side note, I now have a regulator with worn out brushes and have been told that the brushes cannot be replaced in it. Is this true? if not, where can I get brushes? Thanks
Matt
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

There's bench testing and bench testing. One consists of putting the alternator on a bench and staring at it. The other involves an alternator test bench which runs it up with an electric motor and checks it properly - including for maximum output, which is tricky to do without the proper facilities.
--
*I'm not your type. I'm not inflatable.

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

True, and mine was tested on such a bench. It was computerized and ran tests specific to the alternator specified. I have seen the times when a guy puts a belt and a volt meter on it, spins it up and says "yep, she's all good;" doesn't give me much confidence.
Matt
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

;-)
You might as well do this on the car if that's the limit of the test.
--
*I used up all my sick days so I called in dead

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

I heard this too... I think you can replace just the brushes, but it's a bit of a pain. I think they're riveted on, so you'd have to drill out the rivets and replace them with screws.
-Aaron
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Of course you can replace the brushes, you get them at any starter/alternator place. They're like, a dollar. I went in with all sorts of part number and was told BOSCH units only use one part, here they are that's a dollar please.
You might need to do a bit of soldering but it's all very straightforward.
I did this on one of my cars a couple of years ago and made some notes, maybe this is helpful:
        http://articles.mbz.org/electric/reg-repair /
--
Need Mercedes parts? http://parts.mbz.org
Richard Sexton | Mercedes stuff: http://mbz.org
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.