82 240d Alternator not charging battery...help - Page 2 - PeachParts Mercedes-Benz Forum

rwd4evr · #1 06-25-2019, 12:49 AM

Quote:

Originally Posted by Diesel911

On the Alternator Connecto/Plug. You should get Battery Voltage all of the time from the 2 large Slots on the Connector that attach to the Fat Red Wires.

The single Small Slot that attches to the Blue Wire goes to the No Charging light circuit. When the Key is off you should get no voltage there. When the Key is on but not cranking you will get about 1 volt less than the Battery Voltage if the Bulb and circuit are OK.

Ok I'm working on a 85 300sd, got battery light flickering, almost off revving. Swapped regulator and now alternator (can't say 100% it's good but I think they all are). Full battery at both big terminals and 1.24 key off 2.35 key on. What's going on here? Po has the two blue and the grey (that is the smaller terminal) wire nutted together because the terminal block screw is stripped, they all went to that teminal. Testing for voltage at that nut or the smaller alt spade gets the same result.

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79Mercy · #2 03-23-2012, 10:14 PM

Did you check the brushes on the voltage regulator?

JamesDean · #3 03-24-2012, 03:28 AM

Quote:

Originally Posted by 79Mercy

Did you check the brushes on the voltage regulator?

Agreed, you might have an intermittent problem with the brushes. It pretty to remove the regulator. It can be done with the alternator in place on the motor.

As others have said, check all your connections. Perhaps the smaller wire is not connected or broken. There should be two wires on the alternator, the big power output wire and a smaller wire.

This might be helpful, its from the w126, but it should be similar to the 123.

vstech · #4 03-26-2012, 08:44 AM

it's always best to include the year and vehicle make in your title, many will give info without reading what vehicle you have.
the 240D does not have the junction block on the fender. the alt connects directly to the starter harness.
just follow the wires from the alt, to the next junction, at the starter, and clean all connections.
you could also have water dripping on the ground block inside your dash, causing voltage issues with the lights on your dash.

dim lights with the key on, is a ground indicator, so I'd check ALL connections for corrosion...

Hip001 · #5 03-26-2012, 09:11 AM

Quote:

Originally Posted by vstech

it's always best to include the year and vehicle make in your title, many will give info without reading what vehicle you have.
the 240D does not have the junction block on the fender. the alt connects directly to the starter harness.
just follow the wires from the alt, to the next junction, at the starter, and clean all connections.
you could also have water dripping on the ground block inside your dash, causing voltage issues with the lights on your dash.

dim lights with the key on, is a ground indicator, so I'd check ALL connections for corrosion...

Thanks for the reply!
I listed the title as "82 240d Alternator". was that not specific enough?
I will go check the starter connections next. I have been having starter not engaging issues. Where would i find a ground block in my dash? I have the lower dash covers removed on both sides for easy access.

vstech · #6 03-26-2012, 09:26 AM

Quote:

Originally Posted by Hip001

Thanks for the reply!
I listed the title as "82 240d Alternator". was that not specific enough?
I will go check the starter connections next. I have been having starter not engaging issues. Where would i find a ground block in my dash? I have the lower dash covers removed on both sides for easy access.

nah, you listed it as 123 alternator not charging, I changed it for you.
you will need to remove the speedometer cable, and the oil pressure line from the back of your speedometer, and remove the cluster to see the ground cluster...

79Mercy · #7 03-26-2012, 09:31 AM

You need to remove and clean the ground strap between the bellhousing of the tranny and the body of the car.

There is also a ground spot behind the gauge cluster, rarely is this ever a problem but worth a check.

At the end of the day to be honest I think the alternator is bad, have you checked the brushes on the voltage reg?

Hip001 · #8 03-27-2012, 08:08 AM

Oh, thank you Vstech & 79Mercy!
I will check ground straps and Alt brushes today. but remembering back this problem started right after having checked the connections on the starter. I'll double check those connections first.

Hip001 · #9 03-27-2012, 12:40 PM

Quote:

Originally Posted by 79Mercy

You need to remove and clean the ground strap between the bellhousing of the tranny and the body of the car.

There is also a ground spot behind the gauge cluster, rarely is this ever a problem but worth a check.

At the end of the day to be honest I think the alternator is bad, have you checked the brushes on the voltage reg?

So far grounds are looking good, but i cleaned them anyway. How do i check brushes? and will this also lead to no dash light?

Hip001 · #10 03-31-2012, 11:45 AM

Quote:

Originally Posted by 79Mercy

You need to remove and clean the ground strap between the bellhousing of the tranny and the body of the car.

There is also a ground spot behind the gauge cluster, rarely is this ever a problem but worth a check.

At the end of the day to be honest I think the alternator is bad, have you checked the brushes on the voltage reg?

After ALL that troubleshooting, You were right Stewart, If i would of just replaced the D@MN Alternator at first i would of been done with it!! It was different, Motorola, than the
Bosch I had seen on my other 300's.Oh well, I sure learned alot along the way

.

I figured since I was already dirty to my elbows, I'll tackle my starter issue also. Pulled it off and took to my auto electric guy. Come to find out the screw that the actuator pivots on was missing

, lucky this guy is honest. $25 repair cost! WooHoo!! WAY better than the $189 Bosch re-man from Advanced!! Now the 240d is starting and charging as designed!!!

Thank You all for the suggestions and ideas!!!!

79Mercy · #11 03-27-2012, 02:17 PM

Wait, your dash light doesnt come on?

Those grounds look fine, clean the ground at the bellhousing to body also

Take a pic of the brushes

Hip001 · #12 03-27-2012, 02:17 PM

The back of the alt does not look like my 300d where i was able to swap out the Voltage regulator brushes. is this just a different style?
Also i did just clean the ground from bellhousinng and frame. Also tightened the two 17mm bolts on the back of the starter soleniod.

79Mercy · #13 03-27-2012, 02:40 PM

Your alternator appears to have an external voltage regulator, which could be bad since the shop said your alternator was good.

The external voltage regulator should be mounted to the passenger side fender well

Diesel911 · #14 03-27-2012, 04:24 PM

From the pic of the back of the Alternator in Post #24 it did not look like a Bosch Alternator so I did some searching as Member several Years ago had a Motorola Alternator.

Below is the internet address and a Pic of an Alternator labled as Motorola alternator on a Mercedes-Benz diesel

Motorola alternator on a Mercedes-Benz diesel | Flickr - Photo Sharing!

The Ribbed Aluminum Plate either has the Regulator and Brushes or just the Brushes.

You can get parts for Motorola Alternators from NAPA.
Also there is a good chance it is a higher amperages than the Stock Alternator.

Hip001 · #15 03-27-2012, 04:41 PM

Quote:

Originally Posted by Diesel911

From the pic of the back of the Alternator in Post #24 it did not look like a Bosch Alternator so I did some searching as Member several Years ago had a Motorola Alternator.

Below is the internet address and a Pic of an Alternator labled as Motorola alternator on a Mercedes-Benz diesel

Motorola alternator on a Mercedes-Benz diesel | Flickr - Photo Sharing!

The Ribbed Aluminum Plate either has the Regulator and Brushes or just the Brushes.

You can get parts for Motorola Alternators from NAPA.
Also there is a good chance it is a higher amperages than the Stock Alternator.

LOL
You are exactly RIGHT!!! Just came from ANOTHER Auto Electric shop and he determined it is a "Motorola". Said they are not as common as the Bosch and could be $180ish to repair. I got a price from Bennett Auto of $90 w/lifetime wty. I think it is a re-man Bosch. It must be the Alt that is keeping the dash lights from coming on because he had me sit in the car and look at the dash while he did something with his tester and the lights came on bright as can be!!