i think the plug/connector on the back of the alternator might be bad. when i wiggle the plug or wires nothing happens. when i stick the probe from the volt meter in the middle wire to the plug and move it around it will jump to 13.9 or so. then i check it at the battery and it goes to 13.9 or so also. i am pretty sure this is the problem, does any body know how to take this plug apart from the wires so i could clean up and redo all the connections?

 

so i cleaned it out twice once with brake cleaner and the second time with terminal cleaner and brush. both times it didnt work. i would appreciate if anybody knew how to redo the connections?or get a new plug from somewhere....thanks

 

If the female ends inside the plug are only loose, you can squeeze then together with a needle nose pliers so they hold tighter to the male ends on the alternator. If the problem is with the wire contact to the female ends, then you can usually use a pick to hold down the locking tab on the female end, push it forward out of the housing and then cut them and solder new female ends to the wires and pull them back up into the housing.

 

Not common, but I've seen the solder joints inside alternators break and cause this sort of intermittent charging.

 

Here's a wiring diagram I got off the internet. This is for a 1982 300D turbo.

 

If you take a close look the plastic part of the connector snaps together and it will come a part.
I believe you can get a new connector from the Dealer. I do not know if it comes with new female metal connectors. I would call them first if you decide to get one.

 

i pulled out the connections and tightened them all up and put them back in. it didnt work. should i replace the voltage regulator as some people recommended?

 

Ok, so in my case, the alternator doesn't seem to put out enough amperes to handle all the accessories. I can run the headlights, or the compressor, or the electric cooling fan, or the blower motor, but if I try to run all 3 my voltage drops to 12.5 or less which is obviously in a state of discharge. When there is no load, the alternator does 13.4 peak to 13.25 or so when the head lights are on, or when rolling up or down a window. I took apart the climate control system and tested all the diodes inside as well as the resisters and solenoids for the relays to be sure it wasn't just a switch, it isn't. The only thing that has made a difference so far was replacing the grounding cable to the chassis. I looked at the connector after taking it off. It appeared to have been soldered, but the solder was cracked and only a few wires were still connected to the inside of the lug, and it was quite corroded. I replaced the whole thing with a #2 gauge wire, and after that the voltage actually climbed high enough to charge the battery. After this the voltage actually climbs to 13.4, but would not before... Ever.

So in my case, I suspect the load on the system was just slightly more than the alternator could handle with my given issue, so the battery when the A/C was being used was being drained until 9.8v or so whatever it is that the stator field can't charge anymore, and it cut off equaling seemingly instantly dead battery. In actuality it was barely keeping up until the battery voltage dropped too low. Maybe this is your issue also?

For testing, I actually connected my multimeter to the cigar lighter socket and monitored the voltage as I drove. I used the climate control system with just the fan on high, the fan on low, the compressor on with the blower on high and low, and even unplugged the blower motor to test the relays in between the blower and control module. Whenever everything is on, that's when I get into a state of discharge. Only while barreling down the freeway at 65mph, can I turn the AC on and it stays just barely at 13.1 to 13.0 volts, and I think that's because the radiator fan and the auxiliary fans aren't on.

My next step is to replace the alternator pigtail and also check the regulator start/sensing lead (whatever it is) that goes to the starter solenoid. That's really all that's left on mine. I can't think of anything else.

I'm thinking if we compare notes we might help each other solve the issue.

Nivlac

 

i got a brand new bosch voltage regulator and put it in and started the car and checked the voltage which was still around 12 volts...is there something else i should try? thanks

 

i took out the alternator had it bench tested twice, passed both times. tightened the drive belt more, same problem..........?