Hello Guys & Gals,

I've been here for a few problems that yall kind folks have mostly let me in the right direction to alleviate. Let me keep this brief.

(don't know if all of this is pertinent)

about 5 months ago had a friend who I had to boost a bunch cause he kept leaving his lights on. his alternator was dead after a while and he borrowed my battery to get him to the service station. two weeks later my battery died. I bought a new battery from advance.

everything went fine other than a small headlight/tail issuse that's been with the car since I bought it but never seemed to present itself other than one tail light never working and one headlight not working.

about 2 weeks ago i stopped at a filling station and my car wouldn't start.

battery checked good, alternator was bad. got a used alternator off of another volvo i own (same kind, reman off of a 1989 740GL) at first the alternator was reading low at 11.5 volts, i decided to chance it and it failed me on the highway, went back with a fresh battery the next day and drove it home. now I have since had the alternator at two places, at some old timer electro mechanic and he said it read 14.5...didn't trust him....went to the new autozone and they tested it as PASS at 14+.... put the alternator back on the car and it's still not charging.

the car runs fine other than it ain't charging.
the alternator failure light is on, along with the two brake lights and bulb failure (which is to be expected because of particular system construction)

i've read over similar sounding posts and i've correctly wired up all wires, and the belt is taught.

is there a fuseable link that might be burnt through? is there any other main voltage lines or regulators I should look for? main fuses?

I've got the manual and a chilton's book, but I came here first and am going to an old school volvo mechanic tomorrow.

thanks in advance.

btw

1987 Volvo 740GLE 400,xxx miles. New Battery, 2003 Reman'd Alternator, 2004/5 replaced postive terminal and wire, countless number of small electrical flaws.

Sound to me like an earthing problem. Have you checked the earth straps to the engine/alternator from the chassis? are they in good condition? corroded?

other than that, it can be putting out 14 volts and a pass, but under load it could be failing. The best way to test would be to use another known good alt. from another car of same time. A lot of hassle i know, but that would narrow it down to the unit or the car.

if its the unit it could be:

-knackered windings
-dodgy connection
-worn out brushes (on bosch units these are replaceable)

if its the car, check the earth strapping, make sure its good and not corroding.

Matt

Forgive me for being a fool but what are you referring to when you say earth strapping?

And would there be any adverse effects to just running a new positive lead over to the positive terminal on the battery?

when i say earth strapping is from the negative terminal to the chassis of the car there should be a blue cable. from the chassis to the engine block in several places, there should be a braided lead. check these for good quality, replace if broken.

The cars chassis is used as the ground in all electrical circuits. much more efficient than running more wires. plus it can also take a lot more current. everything metal is connected to the negative. in cases with the engine, which is sat on rubber mounts, thus insulated, you have earth straps which attach it to the ground. if these break, then there is no reference to the ground so the alternator will fail to charge.

There would be no harm in running a new wire, other than it looking messy in my mind.

Matt

I know what you are talking about now, we just call all of that the ground or running to ground. Anyway I talked to a random volvo mechanic today and he said the same thing that my ground was probably out and I should run a wire from the case to the negative post on the battery and see if that fixed the problem. Well it didn't change anything from the current situation. When my dad was detaching the "blue wire/ground wire/now a maroon wire cause I accidentaly broke the eyelet off of the end on the intake" I saw all of the error lights go off. The car seemed to run fine and I cruised around all day. Tonight my car broke down again once the headlights and fan was running because it was only running off of the battery, i.e. the alternator wasn't working, i.e. the battery died and so this problem isn't fixed yet.

Is it possible to turn the error lights/failure lights off and there still be a problem? Cause I think by detaching the ground and it turning the lights off it still wasn't making the right connection.

Only thing I can think off is the other wire that leads off of the negative post on the alternator? What does it do? Cause it was shredded in one place and there is a hole in the main wiring harness that goes by the engine where another wire is shredded to bits and it may be shorting something out.

Ideas?

ok ... there should be three posts on the alternator. 2 with thick wires attached, ne blue and one red. these are the main connections. there should also be a small thin wire connected on its on to a thinner terminal. these wires should be intact. the small wire is what indicates if there is enough engine speed to initiate charge. usually idle tbh.

if the grounding issue hasnt solved the problem, check the voltage of the battery when the engine isnt running. should be around 12volts.

Then start the car. dont rev it or anything, let it sit at idle. If the warning lights are on then you'll probably read around 10volts on the battery.

If you rev the engine and the lights go off, thats a good sign. If the battery is then reading 13.8-14.4 volts then your getting power from the alternator. probably just not enough which would mean a new alternator.

If the lights go off and your not getting the voltage of 13+ then definitely your alternator/wiring.

Matt

ps - those dash lights, unless you take the bulbs out, you wont get rid of them. that is also dangerous as you wont know if there is anything wrong.

and from that, I take no responsibility for any work carried out from the advice i or any one else have given if it results in personal injury/death or damage to the vehicle in question. At no point will anyone who posts be held responsible for your actions.

This is what I was saying. The positive wire which is red leads off into the wiring harness, the negative wire or the smaller of the two posts coming off of the back of the alt isn't hooked to anything, and the smaller wire may or may not be shredded, still in tact, but not insulated fully. And in that described condition my car ran and no warning lights were off. If I hook the ground wire back up to the bolt on the underside of the intake then the warning lights come back on.

I've had the alternator checked 3 times, and the third place checked it three times. I've charged the battery and had it checked and it's good. If it ain't the wiring I don't know what is, but since there doesn't appear to be a voltage regulator or anything that could disturb the wiring other than a fault or short and not a fuse or a regulator I'm going to have to check that smaller wire and see if the car changed idle when the small wire is removed.

the voltage regulator is attached to the brushes in the alternator which are removeable on the bosch units.

If the wires are in poor condition, re-connect the alternator to ground and directly to the battery.

Did you try measuring the voltage accross the battery terminals when the car was running? that will tell you whether the wires are ok or not. if you dont get 13+ volts then something is not connected/working.

as you say the people testing the alternator say its fine, and you have had it tested loads of times, so the chances of it being duff are reduced every time it tests OK. If you dont get the voltage across the battery which the alt should be pumping out then you prob have knackered wiring which would need replacing.

your warning light situation is classic of a duff alt. situation OR knackered wiring.

Matt

ok it's been almost two months since I have driven my car because I can't get the battery to charge. I'm getting pretty desperate working on low funds so I am going to up date this thread with a new post in the hopes some one can help.


I have a fairly expensive multimeter I did some testing with. Across the battery with the engine not running I read around 12 volts. it was a little low so I'm not concerned with that. while the car was running i tested the voltage across the battery and it read 11.38, proving the car was consuming more electricty than it was producing.

another test i did was to remove a terminal wire from the post on the battery while the engine was running, as suspected the car died. i was told if the alternator was working properly then the car should continue to run.

the third test I did was to disconnect the wires from both posts on the alternator. i fully charged the battery and started the car. with the alternator properly mounted and all belts in place I hooked up the leads off of the multimeter to the posts to get a reading. alternator A read 9.56volts as the out put, and alternator B read 11.57 as the out put. Neither of these are sufficient numbers to charge a battery, obviously.

Unless there are possible problems with the way the multimeter reads, or the car runs off of the battery, then this should prove both alternators are faulty.


one more tid bit of information.

here is the testing results for both alternator A and Alternator B.

A - first tested bad at advance autoparts at 10.xx volts. second tested bad at autozone at 10.xx volts. then we took it to a old timer electromechanic and he said it was bad but gave me no specs. then we took it to D&G electric and they said it worked fine but the bearing were wearing out.

B - first tested bad at advance (different city though) at 11.xx volts. second test at the same old timer electromechanic tested good, but gave me no specs. third time tested at autozone (tested three times in succession) all tests pass. fourth time time tested at D&G electric tested pass.


one thing I did notice is that everytime it was tested at advance it failed. people have speculated that this is just because they want to sell me an alternator, however I noticed something different about the way they tested it. on the outside of the alternator, the voltage regulator as I have been told, was unplugged and plugged into a special port on their alternator specific wiring harness. every other time I have had they tested everyone left the voltage regulator plugged in. while I trust the knowledge and expereince of the electromechanic and D&G this has always puzzled me. at advance they asked me the model of the car and all the details, then cross checked it with the numbers on the alternators then the testing machine told them a specific wireing harness to use for the test and how to hook it up. this makes me think either advance uses a different kind of machine from everyone else or they are taking into account that the voltage regulator may be faulty. can the voltage regulator be faulty? if so could this be what is causing the alternator to fail the test and be the cause of my charging problems?

any advice, notes, or recomendations.

all of the good volvo mechanics in town have stopped focusing on so much electrical work and they are referring these kinds of problems to one electrical mechanic who charges upwards of 35 dollars an hour to diagnose electric problems :-/

for infomation's sake alternator A is a Bosch OEM Part from my 1987 Volvo 740 GLE. Alternator B is a Bosch style reman from 2003.

thanks in advance

Your alternator needs all three connections to work:
- a blue wire from the alt case to the block
- both small and large red wires connected

With the key on, car not running - is the battery light on? Do you have battery voltage on the post that is connected to the small red wire?

If you don't, it won't charge.

All three wires were always connected when I attempted to drive it and have it operate properly. The only reason I spoke about the wires being detached is I was attempting to get a read out of the voltage the alternator was putting out while being turned by the car's engine and not the testing machines.

And as far as the lights are concerned, all of the warning lights are on, or pretty much all of them (sans the oil light which is always on :-)) which is as I read customary because of system design.

I know how to properly hook up the alternator and I have run leads strait to the battery with no luck as well as running with the original in place wires.

With the key on, measure the voltage on the small red wire post with everything connected. If you have battery voltage, you can pretty much assume the regulator is bad, which held in by two screws in the back of the alternator (and can be replaced).

If you don't have battery voltage on the small red wire, the alternator is NOT your problem.

if your not getting charging voltage from the regulator then its definitely that. the wiring inside the alternator rarely goes wrong ... its the brushes attached to the regulator. mine went and i was reading 10 volts at 3000rpm ... stupid!

change the regulator over from my 940 and worked a treat. 14.2v output. all was swell.

Matt

Just to clarify, I might possibly be the dumbest volvo owner/shadetree mechanic ever.

The Battery was fine.
The New Alternator Worked Properly and
There was no problem with the wiring.

On the alternator there are technically three posts. Two of them were copper and one was steel. I had been hooking the blue (ground) wire to a positive post. The main red wire to the battery connected to the biggest of the three posts. The second post (which I was connecting the ground to) was only intended to have the small regulator wire hooked to it. Because it connected to the wire via a slip on bladed connector for some reason I was still trying to connect another wire to it. The "third" post is just a longer frame screw that the ground wire connects to, which only "touches" the case, as it's a main screw that holds it together.

If I had only looked and considered that my ingenuity (or lack there of) could be at fault, I would have figured this out 3 months ago and had a car to get a job this summer. Perhaps it was all good because of the gas money I saved, lol.

It took a salesman at Advance Autoparts to show me the err of my ways. He pointed out that the black plastic guard around the two copper posts contains a big embossed +. If I had seen that, I'd have known the ground didn't go there, doh.



Thanks for everyone's input even though it was all in vain cause I'm a fool.