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Ive been tinkering with my new wagon, attempting to remove the major bugs.

Here's my symptoms: brake light, brake lining are lit, as well as fuel low gauge. Interesting. No battery light when key was put to run. When it would start, the lights stayed on.

First thing I did was swap out the battery bulb. With excitement, i fired her up and tada! ... Still not charging, but now battery, brake lining & brake light are on.

I checked and found voltage at that single wire on the alt with the key in the run position, so I decided, must be voltage reg or alt itself. It was extremely crusty, and my buddy had one. I went and snagged it, put it in, along with all new belts, fire it up... Same thing. Now, heres an odd thing. Its night, as i got to higher RPMs the lights dimmed, but didnt go out. Also, voltmeter says it went to 12.65 up from 12.25ish.

So, by the dimming lights while the alt gives a little bit of juice screams bad ground behind the cluster, but could this actually stop the system from charging?

Dave aka Ghan
 

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Discussion Starter #2
31 views and nobody has any thoughts? :p At least throw me a 'yeah man, you're f*ct!' :p
 

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1985 300CD Turbo coupe, 2006 E320 CDI sedan
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From my perspective, you jumped too far ahead into the problem. I always start with basics, and work my way in. Perhaps you should consider taking the car to an auto parts store and take advantage of the free electrical system tests. Start by knowing whether or not you have a good battery/alternator/regulator/et cetera. If they don't do it automatically, also request that they check for voltage on ground.

//greg//
 

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Discussion Starter #4
Perhaps you should consider taking the car to an auto parts store and take advantage of the free electrical system tests. Start by knowing whether or not you have a good battery/alternator/regulator/et cetera. If they don't do it automatically, also request that they check for voltage on ground.
I hadn't really thought of that - my local shop, while sometimes have reasonable prices, is often quite crappy for skill... I sent my GF in for belts the other day, she requested 2 alternator belts and the power steering belt. They gave her power steering, one alternator and one AC belt. She didn't notice, and got to go back to them. They argued with her and told her no cars have 2 alternator belts....

Well, needless to say, I wouldn't really rely on them having any idea how to test things... Is the 'voltage on ground' test something I can do at home with a multimeter?

Dave aka Ghan
 

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Yes just use a multimeter and you can check the amps or voltage, you can check the alternator while it is running to to see if it is putting out the correct amount.
 

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2001 Volvo V40
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The only thing that would prevent charging is the incorrect alternator light bulb, that should be 3W.

The other warning lights staying on is strange, I would start by taking of the plug and cleaning the contacts and also check the ground contact. Otherwise the oil-temp-fuel clock is broken (the circuit board can be damaged, that happens).

In any case the voltage should be 13.8 to 14.4 V with a running engine, if not, the alternator or voltage regulator is broken.
 

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Discussion Starter #7
The bulb I replaced it with was a brand new 3w bulb. It's the correct one, I double checked before I bought it.

It's definitely not charging at the mid 12v so for some reason it's not 'exciting' the alternator. It COULD be a bad voltage regulator, but it is the 2nd in the vehicle with the same issue, so I'd like to try other things too.

I'm still curious on the 'voltage on ground' - how does one perform this test? What does an auto shop do for that test?

Dave aka Ghan
 

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1985 300CD Turbo coupe, 2006 E320 CDI sedan
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I'm not sure the voltage regulator is involved in the charging circuit, but you can isolate it just for good measure. Remove the wire from the alternator B+ post. Make a test lead from 10ga wire, then connect that post with the battery + post. Measure voltage between battery + and - posts. Start engine. Measure again. The difference between second and first measurements is the amount of charging voltage. On a normal system, you'd expect 12.2v before the engine starts, up to 14.5 or so after.

To check for "voltage on ground", you actually set the meter to detect amperage. I recommend a DMM over an analog meter. Engine not running, keyswitch to OFF. Disconnect one of the battery cables, it doesn't matter which one. Set the DMM to read amps. Put one lead on the vacated battery post, the other lead on the cable end you just removed. If amperage is detected, you have voltage on ground. To help narrow down the short, pull one fuse at a time. When the amperage drops back to zero, you've found the guilty circuit. That's the easy part. Then you have to find WHERE in that particular circuit the problem may lie.

//greg//
 

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//greg// - I now understand fully and wish I was not at work so I could go play! Thanks for the tip! I'll report back tomorrow if I still have the heart & soul to try it tonight!

Dave aka Ghan
 

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Here's the scoop!

So, after much agony, I have solved the issue.

There were multiple problems.

1- My alternator light bulb was out in the dash. replaced with proper 3w bulb.
2- The gauge cluster needed a ground. More importantly, it needed a ground due to burn traces on the circuit board of the fuel/oil/temp gauge cluster! Here's what I found:



Broke out the soldering iron, bypassed the traces with wires:



Once that was done, I also noticed the thing that PROBABLY torched the lines in the first place was... the dimmer! I took the rheostat apart and cleaned it. Lots of corrosion & powder in it. little bit of sandpaper, it was good as new. Dash illum now works as intended!

Once back together, I put it back in the dash and made another ground wire from the speedometer housing and the general ground area, just for good measure. I probably didn't even need it, but now at least there's a place for voltage to go, other than burning more traces! :)

This cleaned up all the lights on my dash, except for the alternator. So, I did what I didn't want to do, swap it out AGAIN. Sure enough, the 'new' one I had put in was bad, but the one out of my parts car was known good, and it was. Mission Accomplished! I hope this helps others!

Dave aka Ghan
 
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