Generator light stays on

[mkuftinec]

My 350SL [most everything ios original, its battery is only 1 yr old] has a prob lem that is driving me nuts! For a while it was intermittent, now it is permanent
the generator light does not go off, it is always on ...
what have I done so far: several times [with 3 different meters, just in case!] measured the system's voltage running with and without any load. Without elec consumers it reads 13.6V, with everything I can put on reads 14.4V. Shut off the engine, monitor the voltage drop - not recordable/insignificant,none
On a suggestion of my neighbor [a certified MB mechanic] I cut the + cable about 2" from the battery terminal, cleaned everything, attached a new clamp - light stayed on. Removed the - terminal from the car, cleaned and checked its IR [meter from one end to the other] essentially 0 ohms; measured battery's cells, all are good and strong. The car starts and drives fine, but with the light on. I observed that the intensity of the gen. light changes slightly when I put it in the gear or turn on large consumers [headlights or a/c], but it does not go off. I attempted to follow the famous 'exciting thin red wire" - it appears to be OK, although i have not been able to figure out how to access both its ends. Also I have not removed the + battery cable from the starter, in order to measure any IR loss, but the car starts without any hesitation. I'm totally puzzled, frustrated, mad .. what else can i do to find out the reason for that light to stay on when the engine is running? Please help me, educate me, prove me incompetent, PLEASE!
Oh, yes, the car has original 57K miles and is in a remarkable shape. No rust, no dents, nothing. Any interest in buying it? Thanks in advance. Miki

[mkuftinec]

will anyone out here help me with advice? please do so.
one new problem: on my old, 1970 280SE the ignition vacuum advance sensor is probably busted [the car starts, but then immediately dies] I cannot locate a replacement part. I can provide the OE part number,a photo or other info. Does anyone have one or can direct me where to look for it?
Mioki

[Frank Reiner]

mk:

On the back of the alternator will be either a plug with three wires in it, or two stud terminals, one large, one small. In either case, there will be a blue wire that is much smaller than the other, red, wire(s). If a plug, pull it from the alternator, attach the positive lead of your volt meter to the blue wire socket in the plug, and the negative meter lead to ground. Turn the key on (not start). Do you read battery voltage on the meter? (If the blue wire is on a stud, remove from the stud, and attach meter to wire.)

If there is battery voltage at the blue wire, good. The fault will most likely lie in a set of three diodes in the alternator that are not the main rectifiers, but are connected only to the blue wire and to a circuit in the voltage regulator.

If there is not battery voltage at the blue wire, some additional wire tracing will be required.

[jimandsuzy]

You need a new voltage regulator which plugs into the alternator. China mfg can be had for less than $10 or euro name on the box but still mfg in china go for $38 and up. I've used both without problem. IIRC only 2 screws hold the regulator.