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-   -   Is there a way to tell if I need an alternator or the voltage regulator? (http://www.peachparts.com/shopforum/tech-help/387562-there-way-tell-if-i-need-alternator-voltage-regulator.html)

ChrisArnt 07-25-2017 11:46 AM

Is there a way to tell if I need an alternator or the voltage regulator?
 
1996 E300D
Is there a way to tell if I need an alternator or the voltage regulator?

TX76513 07-25-2017 11:53 AM

On your W210 the voltage regulator is the brush pack. If you meter the + - terminals with the engine running your voltage should be north of 13.6VDC.
The brush pack is the likely suspect and its two screws to remove and not an expensive part. When you seat the brushes back in compress the brushes with a piece of dental floss, insert then pull the floss out and put screws back in.

ChrisArnt 07-25-2017 12:34 PM

I just tested my alternator with my smart charger and it read "Alternator OK"
But voltage was down to 11.89. Which is what it was on the battery I just replaced.
I drove it yesterday. Drove it this morning. No check engine light.
I started the car about 6 times and immediately turned it off to check for warning lights.
Check engine light back on.
It was off this morning.

TX76513 07-25-2017 12:40 PM

Fully charged batteries should have a voltage reading of +12.6 volts static (no engine running)
With the engine running the battery reading should be 13.6 - 14.5VDC
There is a warning light for alternator on the bottom of the cluster.
What code is present when the check engine light comes on? The check engine light is something else.

ChrisArnt 07-25-2017 12:51 PM

I have to read the codes.
I will check the voltage when it is running for higher than 13.6 - 14.5

ChrisArnt 07-25-2017 03:18 PM

Quote:

Originally Posted by TX76513 (Post 3732120)
Fully charged batteries should have a voltage reading of +12.6 volts static (no engine running)
With the engine running the battery reading should be 13.6 - 14.5VDC
There is a warning light for alternator on the bottom of the cluster.
What code is present when the check engine light comes on? The check engine light is something else.

When the car is running it reads 12.2 volts. This is about 10 minutes after I topped off the charge on the brand new battery.

I tested the alternator using my smart tester and it said ok, but obviously it is not charging

I don't have the code reader. BUt the last time I ran it it said glow plug relay or pre-glow timing relay.
BUt I tested that and it is fine as are my glow plugs.

tjts1 07-25-2017 04:00 PM

Check the voltage through the CCU while driving. It should be above 14v. The CCU # will be 0.5v below the reading at the battery so add 0.5v to whatever number u see on the display. You likely need a VR.
http://www.mbcluster.com/Old_Website...%20Reading.jpg

Zulfiqar 07-25-2017 04:49 PM

the test to isolate those two pieces is called a full field test, on an old Bosch it requires the DF and D/B to be shorted.

It is quite easy on japanese and american alternators, a bit involved on german. I would suggest you stick these terms in google and search for it, that way you can learn the test and its results.

mpolli 07-25-2017 07:21 PM

Your smart tester isn't very smart if it thinks 12V is a good charge voltage, or a good voltage of any kind. Might need a visit to the recycling can. New regulator as was said.

ChrisArnt 07-26-2017 09:42 AM

Quote:

Originally Posted by mpolli (Post 3732244)
Your smart tester isn't very smart if it thinks 12V is a good charge voltage, or a good voltage of any kind. Might need a visit to the recycling can. New regulator as was said.

I have been thinking that years of partying have made my smart tester not so smart.

ChrisArnt 07-26-2017 09:42 AM

Quote:

Originally Posted by Zulfiqar (Post 3732199)
the test to isolate those two pieces is called a full field test, on an old Bosch it requires the DF and D/B to be shorted.

It is quite easy on japanese and american alternators, a bit involved on german. I would suggest you stick these terms in google and search for it, that way you can learn the test and its results.


What is DF and D/B?

ChrisArnt 07-26-2017 10:16 AM

Quote:

Originally Posted by TX76513 (Post 3732098)
On your W210 the voltage regulator is the brush pack. If you meter the + - terminals with the engine running your voltage should be north of 13.6VDC.
The brush pack is the likely suspect and its two screws to remove and not an expensive part. When you seat the brushes back in compress the brushes with a piece of dental floss, insert then pull the floss out and put screws back in.

I've never done this.
Can I do it with the alternator in the car?

Zulfiqar 07-26-2017 10:36 AM

Quote:

Originally Posted by ChrisArnt (Post 3732339)

What is DF and D/B?

sorry bout that,

DF, B, D and W are pin designations on bosch alternators.

ChrisArnt 07-26-2017 11:04 AM

OK.
So to isolate the alternator for testing I need to put a jumper pins D and B to each other and what do I jumper DF to?
Can I do this on the car?
Do you have a visual?

Then I can put my meter on the positive and the negative terminal of the alternator and read the true output.

ChrisArnt 07-26-2017 11:08 AM

Quote:

Originally Posted by tjts1 (Post 3732194)
Check the voltage through the CCU while driving. It should be above 14v. The CCU # will be 0.5v below the reading at the battery so add 0.5v to whatever number u see on the display. You likely need a VR.
http://www.mbcluster.com/Old_Website...%20Reading.jpg

Here are the results of my readings and error codes. What do you think?
http://www.peachparts.com/shopforum/...rror-codes.jpg


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