hello. new to the site. i just picked up this beast for cheap and have had nothing but problems since! this site has been a huge help, though. now, on to the alternator. the old one was not charging, took it to nearest parts store and it failed the test across the board. the old one did have the small black and red wires disconnected when i purchased the vehicle but hooking them up did not fix problem. so i installed the new one and hooked up the large red wire, the black wire to the oil pressure switch(?) and the small black wire to wherever that is grounding. left the small red one off. still at 11.5 when running. i jumped on here and discovered how the red wire is the exciter wire and must be hooked up to work. now, my battery light is on in key position 2 so the exciter wire is connected but i'm STILL not getting a charge while running. basically, i'm so bad with a voltmeter that i don't even know what to poke to find out what wire could be bad. i know it. anyone have some helpful insight?

 

is the dashboard alternator light coming on when you turn the key to II (on but not started) ?

if not, then check the exciter circuit. disconnecting that exciter wire from the alternator and grounding it should light the light when the key is on, if not, maybe that bulb is bad.

no exciter == no charging.

if the light DOES light, does it go out when the car is started? if not, then its either hooked up wrong, or the replacement alternator is no good.


odds are /very/ good your original alternator just needed new brushes, which come with the regulator module.

 

thanks for the reply! the battery light does come on in key pos. 2 along with the oil light. but then when i start the car, all the lights come on the dash including the bulb warning and parking brake light. i looked around the car and all bulbs are functional. also, still no charge from the alternator. goes down to 11.5 or so at battery. the new alternator did come with a new regulator in it but i had to swap the old thing that looks like a small condensor and connects via a blade connection. wasn't even sure what that was. could that be bad? i'm pretty much trying to sell the car so any shiny new parts that people can see will be a better selling point. the whole alternator was only 70 something bucks.

 

sounds to me like something is wired wrong. all the dashboard lights should come on in key position II and go OUT when the car is started.

the alternator D+ (exciter) circuit is like, battery -> ignition key -> alternator light -> D+

D+ is on its own diode inside the alternator, and is at ground when the alternator isn't working, so if the key is on, the light comes on. D+ provides the tickler current required to bootstrap the alternator, once the alternator is making power, D+ should be at the same voltage as B+ (which is the output wired to the battery), so that dashboard light should go OUT

 

Tension on the alt belt good...I did not tension it well and bought a batt and alt for no freaking reason...my tension was bad...

 

oooook. so i returned the rebuilt alternator just because and got another one. same thing. the battery light is coming on in key pos. 2 but would not shut off while running. still 11.7 from battery. we discovered that the only way to get the alternator to charge was by touching the back stud with a power probe. it would jump to life and the light on the dash would go out and we'd have proper charging voltage. shut it off and back to no charge. so if the battery light is on, the exciter wire is connected but still not giving the charge to jump my alternator to life......is that my ignition switch?

 

sounds to me like the exciter wire that goes to the dash light is connected to the wrong place on the alternator

 

pierce, thanks for your responses. i'm sure i'm frustrating but you're a big help. when i got the car, it seems everything was backwards so i pretty much went in blind with wiring (not that an alternator is too hard). so the exciter should be hooked up to the d+ stud? that's the one with the wire going to the oil pressure switch also, correct? after looking, i've had it connected with the large power wire just because i thought red and red should go together and i didn't want anything to blow up when i hooked up the battery. would you venture to say that's my problem?

 

the ONLY thing hooked up to D+ should be the exciter wire to the dashboard alternator light, which is a skinny red wire, the other end of which goes into instrument panel connector 31/11

the oil pressure sensor on the exhaust side of the engine block near the oil filter should be hooked up to is a black wire that goes to pin 31/5 of the instrument panel (eg, the oil pressure light). the oil pressure sensor is a switch to ground when there's no or very low oil pressure, and open/off when there is normal oil pressure.

instrument panel connector 31 is the full circle one.

 

thank you, sir. the snow is gaining inches in no time where i'm at so once that stops i'll switch that all around. hopefully there's no other problems. any ideas on where to find a tensioner bolt for the alternator bracket? that was also missing.

 

I'd probably be checking with my local volvo dealer for that, or ordering it from TascaParts.com

 

this is exactly what was wrong with my alternator too...ive found when it's the most frustrating, the answer is usually the simplest

 

haha. tell me about it. the alternator is now doing it's job! however, my oil light is still on (checked the oil) and after driving it ten miles i lost my 3rd and passenger side taillight. i'm a pro at getting in over my head with projects. it's on the local craigslist for best offer though so let's see what this tan pig can bring in!

 

that black(?) wire to the oil sensor, if its disconnected, the oil light should go off, if its grounded, it comes on.

that sensor measures oil PRESSURE, not amount of oil. I see three possible scenarios here.

1) oil pressure sensor wiring is shorted to ground somewhere, and the test above won't work
2) oil pressure sensor has failed, and is stuck 'on'.
3) your engine is on its last legs and has insufficient internal oil pressure.


3 is catastrophic.

 

HI Pierce, '86 240 DL; reading a response of yours to a guy in 2010 with new alternator that is not charging - which is my exact NEW problem. I've got new batt, new starter, new alternator but battery keeps draining during operation. You mention in this post 'a regulator' (and that new alt brushes come with a regulator kit) is there a regulator external to the alternator that could prevent a charge to batt?

 

the regulator is screwed onto the back of the alternator. in this picture, its the black thing thats between the ground and B+ posts...

and yes, if the regulator is bad or the brushes are worn out, you won't get proper charging voltage. however, a new alternator should have a new regulator, so quite likely its a wiring or grounding problem.

the D+ wire is quite important, the alternator won't charge without it. when you turn on the ignition, the red BATT (or is it ALT?) light should light up. when you start the engine, it should go out (maybe after blipping the throttle).

measure the voltage from the alternator ground to the battery - post with the engine running. this should be 0.0 volts. if its not, check the grounds. measure the voltage from the alternator B+ to the battery + terminal, this too should be 0V, if its not, check the B+ cables (they go alternator B+ to starter, then an even fatter wire from starter to battery +).

 

Thanks!

 

Just like the previous person stated, the voltage regulator is important. We have a 1993 Volvo 240 Wagon that was not charging either. We went to the local junk yard and found a 1991 Volvo 240 ($16.00), removed the alternator and tried it in the 1993 Volvo 240, at first it failed to charge, then I took the voltage regulator off the other alternator (1993) and placed it in the 1991 alternator and it worked. So, the original 1993 alternator must have had an issue with the diodes or something else. And the 1991 alternator just needed a voltage regulator. Everything is working great now.

The voltage regulator brushes (1993) were worn, but not as bad as the brushes on the 1991.

I hope my experience helps. Budget is tight. Junkyard helped.

 

Thanks. That does help -

 

another volt meter test.

fully charge the battery overnight, take it off the charger, let it sit an hour (or a day, close enough). measure the battery voltage, it should be around 12.6-12.8V assuming 'room temperature'.

switch on ignition without starting engine, and measure the voltage at the D+ terminal (relative to ground), it should be around 7-9V or something, eg somewhat LESS than the battery voltage.

now start the car, and the D+ voltage should be essentially the same as the B+ voltage, about 13.8-14.4V.