Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help




Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Diesel Discussion

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 08-09-2008, 09:27 AM
777funk's Avatar
Registered User
 
Join Date: Dec 2006
Posts: 955
Where does the Alternator's 3rd wire Control Voltage come from?

New Alternator and still no charging. I noticed that the blue wire (the small pin on the alternator's 3 pin harness has no voltage on it. I think it's supposed to have a signal that the car is running so turn the alternator's power on. But where does that signal come from?

Help me understand the alternator wiring.

thanks!
Nick
__________________
-Suburban '93 220k
-Diesel Jetta '03 350k

Sold
--E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia Missouri Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's!
Reply With Quote
  #2  
Old 08-09-2008, 09:30 AM
79Mercy's Avatar
Registered User
 
Join Date: Mar 2008
Location: Florida
Posts: 4,128
I think that blue wire is what controls the dashboard light. Check and see if it has voltage when the key is in the "on" position.
__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg
Reply With Quote
  #3  
Old 08-09-2008, 09:39 AM
777funk's Avatar
Registered User
 
Join Date: Dec 2006
Posts: 955
Quote:
Originally Posted by 79Mercy View Post
I think that blue wire is what controls the dashboard light. Check and see if it has voltage when the key is in the "on" position.
Thanks! No voltage when the key is on.
__________________
-Suburban '93 220k
-Diesel Jetta '03 350k

Sold
--E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia Missouri Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's!
Reply With Quote
  #4  
Old 08-09-2008, 09:40 AM
79Mercy's Avatar
Registered User
 
Join Date: Mar 2008
Location: Florida
Posts: 4,128
when you turn the key "on"(not running) does the battery light on the dash come on?
__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg
Reply With Quote
  #5  
Old 08-09-2008, 10:03 AM
777funk's Avatar
Registered User
 
Join Date: Dec 2006
Posts: 955
Quote:
Originally Posted by 79Mercy View Post
when you turn the key "on"(not running) does the battery light on the dash come on?
lol! Actually I am waiting to receive the gauges you'd sent so I've still got the cluster torn apart in the basement

I'm betting they'll be here today!
__________________
-Suburban '93 220k
-Diesel Jetta '03 350k

Sold
--E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia Missouri Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's!
Reply With Quote
  #6  
Old 08-09-2008, 10:08 AM
777funk's Avatar
Registered User
 
Join Date: Dec 2006
Posts: 955
Oh... Also, to add more to help describe the situation... I do measure the 12.5V battery voltage at the 2 large terminals.

But of course no 13.5 or higher when the car is running.

I stuck the Red Multimeter probe into the back of the plug connector itself on the Alternator and measured 12.5V with the car running. That doesn't mean that the connectors are making a good connection on the alternator since I'm not touching the pins just the wires on the back of the Alternator harness. A bad connection may be the problem. But with the old Alternator I measured on the two large pins at the Alternator (not the plug) and didn't measure any voltage. I'll try it on the new one and see.
__________________
-Suburban '93 220k
-Diesel Jetta '03 350k

Sold
--E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia Missouri Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's!
Reply With Quote
  #7  
Old 08-09-2008, 10:16 AM
777funk's Avatar
Registered User
 
Join Date: Dec 2006
Posts: 955
Ok... measured at the Alternator's 2 big pins and I didn't measure any DC voltage with the engine running with reference to the batteries ground post.
__________________
-Suburban '93 220k
-Diesel Jetta '03 350k

Sold
--E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia Missouri Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's!
Reply With Quote
  #8  
Old 08-09-2008, 10:29 AM
Registered User
 
Join Date: Jul 2008
Location: Oklahoma City
Posts: 159
alternator

I am having alt problems myself. Others on the forum have given the following suggestions. So far it hasn't helped me but it may you.
Check the terminal block connections, if you have one.
Connect a ground wire from the alt housing to batt ground, the alt must be grounded to work.
Check the ground cable where it connects by the hood hinge.
Hope you find your problem.
__________________
Darrell

1984 300SD "Ole Girl"
207K
Reply With Quote
  #9  
Old 08-09-2008, 10:34 AM
Registered User
 
Join Date: Jun 2004
Location: West of Ft. Worth. TX
Posts: 4,144
Quote:
Originally Posted by 777funk View Post
lol! Actually I am waiting to receive the gauges you'd sent so I've still got the cluster torn apart in the basement

I'm betting they'll be here today!
Without the instrument cluster installed, you won't see any charging. Power comes from the fuse, through ignition switch, then charge indicator to blue wire of alternator. The blue wire is the "excite" wire that measures the voltage and "turns on" the alternator to charge.
__________________
Sam

84 300SD 350K+ miles ( Blue Belle )
Reply With Quote
  #10  
Old 08-09-2008, 10:45 AM
yellowbenz's Avatar
Registered User
 
Join Date: Jun 2005
Location: Columbia, Missouri
Posts: 643
I'm like a one trick pony when it comes to this problem but as I post on every one of these charging threads replace the belt and tension it well. However, you won't know if this is a problem until you complete the circuit for the exciter wire to the alternator.
__________________
Kevin

1978 300D
1979 240D
Reply With Quote
  #11  
Old 08-09-2008, 12:57 PM
79Mercy's Avatar
Registered User
 
Join Date: Mar 2008
Location: Florida
Posts: 4,128
just wondering, how did you run the motor with the cluster out of the car(oil pressure gauge)?
__________________
1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg
Reply With Quote
  #12  
Old 08-09-2008, 01:09 PM
Diesel911's Avatar
Registered User
 
Join Date: Sep 2007
Location: Long Beach,CA
Posts: 27,835
I had thought 777funk had ask the question that I wanted to know about.
Why are there 2 (+) wires with battery voltage going to the Alternator (the 2 large slots on the connector)?

I bought the Bosch book on Alternators and Starters and still no answer to the above question.
In the Bosch book it said you need to have a least a 2 watt bulb in the circuit where the blue wire goes in order to "excite" the alternator to start charging.
__________________
84 300D, 82 Volvo 244Gl Diesel
Reply With Quote
  #13  
Old 08-09-2008, 02:04 PM
lowriderdog37's Avatar
Unregistered User
 
Join Date: Mar 2007
Location: Viera, FL
Posts: 665
Quote:
Originally Posted by Diesel911 View Post
I had thought 777funk had ask the question that I wanted to know about.
Why are there 2 (+) wires with battery voltage going to the Alternator (the 2 large slots on the connector)?
2 10-gauge wires in my eyes provides a backup in case one breaks...it also provides the ability to contain much more current at any given time. Could be either/both

Quote:
Originally Posted by Diesel911 View Post
I bought the Bosch book on Alternators and Starters and still no answer to the above question.
In the Bosch book it said you need to have a least a 2 watt bulb in the circuit where the blue wire goes in order to "excite" the alternator to start charging.
The dash light could work as the 2 watt bulb in that situation. I haven't found any wiring diagrams though
__________________
My Primary Driver - '85 300CD - 4-speed conversion, 2.47 rear, lowered, euro headlights, rebuilding (not restoring so much)

Wife's - '08 Saab Sportcombi Aero

Riding a '03 Yamaha Warrior
Reply With Quote
  #14  
Old 08-09-2008, 02:13 PM
777funk's Avatar
Registered User
 
Join Date: Dec 2006
Posts: 955
Quote:
Originally Posted by 79Mercy View Post
just wondering, how did you run the motor with the cluster out of the car(oil pressure gauge)?
Got the gauge today. I'm about to open it and give it a go! Thanks!!!

You'll laugh but I actually drove the car with NO cluster. I just put a piece of cut rubber (to the size of the hole in the oil pressure gauge) into the old gauge to plug it and off it went. The 617 runs fine with out power.
__________________
-Suburban '93 220k
-Diesel Jetta '03 350k

Sold
--E320 '95 200k
-E320 Wagon 1994 155k
-300d Turbo '87 187k miles
-E320 1994 200k
-300d Turbo '84 245k (sold to Dan62)
-300d Turbo '84 180k
-300sd '80 300k
-7.3 Powerstroke Diesel 15P Van 500k+ miles
-190d '89 Non Turbo 2.5 5cyl 240k (my first MB)
Tom's Imports of Columbia Missouri Ruined the IP in changing leaky delivery valve O-Rings - Refused to stand behind his work. Mid-MO MB drivers-AVOID Tom's!
Reply With Quote
  #15  
Old 08-09-2008, 02:14 PM
compress ignite's Avatar
Drone aspiring to Serfdom
 
Join Date: Feb 2004
Location: 32(degrees) North by 81(degrees) West
Posts: 5,554
Two (2) #10 AWG wires(or the Metric eqiuvalent)

The first place I was made aware of this set up was on GSXR's instructions
about converting to the 143 or 150 amp Alternator.
(I believe he replaced them with a Great Big Honking single cable with the
diameter of your thumb.)

(Maybe Deutschland was short on 1.0 and 2.0 ?)
__________________
'84 300SD sold
124.128
Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 11:27 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page