Charging question

5ft24 · Post by **5ft24** » 14 Apr 2013, 13:08

I have a 1990 740GL.
When I drive with the headlights on, the alternator charges less than adequately... at Idle, below 1000 RPM, the voltmeter will drop almost to the bottom... A volt meter on the battery shows 13.6 or so at idle with no accessories on. When I turn on the headlights, I have about 11.8-12.0 at the battery.
On the alternator, there is a piece of 12guage wire from a small stud on the rear to the Idle speed control bracket serving as a ground. It's hot as heck and shows a voltage drop of over 1 volt across it.
Is this the way the alternator is supposed to be grounded?
Thanks

Post by **billofdurham** » 15 Apr 2013, 12:36

Welcome to Matthew's Volvo Site.

That is how the alternator is earthed (grounded), although I can't recall the exact location, the idle speed bracket does not seem familiar. However, if the wire is getting hot it is either not strong enough or it is failing. I would replace it with something heavier and would be looking at a better earth point.

Bill.

5ft24 · Post by **5ft24** » 15 Apr 2013, 13:30

Thanks, Bill
I'm going to see if I can make a shorter and heavier ground path for this guy...
Thanks

5ft24 · Post by **5ft24** » 16 Jun 2013, 09:57

Used a length of #4 wire. No more voltage drop, but still weak charging. Pulled the regulator and there was nothing left of the brushes. (345K miles). New regulator and it's like new!