82 240d Alternator not charging battery...help - Page 3 - PeachParts Mercedes-Benz Forum

Diesel911 · #31 03-27-2012, 04:49 PM

Quote:

Originally Posted by Hip001

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!!

I added this thread to my Old one on the Motorola Alternator as it has better pictures.

Hip001 · #32 03-27-2012, 10:26 PM

Just found out, My AMAZING mechanic & friend Pierre has found me a Alternator!!

THANK YOU Pierre!!!

Hope to have this on soon!!

Hip001 · #33 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 · #34 03-31-2012, 07:53 PM

Glad to hear your got her charging again

rwd4evr · #35 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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rwd4evr · #36 06-25-2019, 01:10 AM

Ok. So running I have 14.3 at the blue/grey third terminal but battery voltage isn't changing. Like 12.2. I even swapped batteries thinking mine was bad. WTF? should I pull a VR from a good car I guess for sh*s and gigles?

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rwd4evr · #37 06-28-2019, 01:34 AM

Well if anyone comes across this thread searching for answers. Make sure the three prong plug or any rebuilding of it isn't corroded even possibly internally up in the wires. I had resistance at the spade terminals and all I had to do to fix it was a new field wire and the two battery wire harness from another car. Two days of head scratching test metering, alt swapping, plug pulling more head scratching wire diagram reading. Bonus is that it was free to fix from a parts car and I now fully understand how the charging system works and can even upgrade it with a newer higher output model from a r129 or w124.

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