Have a 94' 945T with 125,000 miles on it. Recently have noticed power drain from the engine when using power windows, car noticeably under idles in park lights will also dim. Usually happens when two window switches are depressed at once. Found this ought by accident just happen to be rolling up two windows at once. I know the 940's are known for little quirks such as radio staying on briefly after car is turned off, but I was wandering whether this is a sign of a failing alterantor, checked the battery, terminals are clear and the battery cells are full. checked all fuses, didn't look into relays not sure of they pertain, car starts right up in the morning or after its been run a while and restarted, no loss of power is appreciable. Could it be a short, it has been raining alot here lately, have no leaks but driver's side window was left down during rain about a month ago, have just noticed the problem now, but could have been going on since then. It could just be nothing and I am delusional,
Pleas advise, it would be much appreciated, all info I have gotten from the post in the past has been right on.
Moles

Well, power windows do draw quite a bit of current... and alternators don't do much charging at idle... but if the condition is bad enough to bother you I'd suggest doing a voltage test, and see just how low the system voltage gets when you do this. The brushes in the alternator are a pretty easy fix, so if it is weak, I'd start there. Just remember to have your radio code handy for after you connect the battery again.....
===
Rob Bareiss, New London, CT ::: 86 244DL, 87 244DL, 88 744GLE

As brushes get worn down, the springs have to reach further to press the brush on the slip ring. The farther the reach, the lower the pressure. Your problem sounds much like mine, on a 1988 244GL. Replaced brushes, and not only did the dimming light problem disappear, but the engine ran better and started quicker.

It's an easy fix, I think your alternator is high mounted, compared to my 240. Get a new brush/regulator unit - I use a dealer part here - and put it in. Check the two screws, they may be Philips or Torx head, and be sure to unhook the battery.

Later you can order some brush sets, about $3.00 plus shipping, and solder new ones into the unit you remove. Then you'll have a spare, ready to pop right in when you hit 200,000 miles!

Good Luck,

Bob
:>)

How good is the battery? The battery should carry the electrical system even if the alternator is operating at low speed. I would expect the alternator to either work 100%, or not work, at least that is my experience.

Even if the alternator brushes are getting short, if they carry enough current at load RPM, they should carry enough current at idle RPM. But you could check them.