Ok here it goes, 2 weeks ago the 'power system service urgent' light came on, I replaced the batttery 2 months ago but took it out and had it checked and came back fine, then had alternator checked and also fine, then yesterday took it to autozzone which his reader said sterter system failed, so before anything else I took out starter and had it checked and it was fine, so now what are my options? there are no codes on file to check on the 'power system service urgent' light is on, any suggestions??????

 

I would check the battery voltage with the engine running for ~14 volts with a digital multi-meter. (If you don't have one multi-meters are very inexpensive from Lowes, Ace, even Autozone) Also, with the engine off check for ~12 volts at the battery.

The normal issue would be a failed alternator. Of course your battery then drains and the car fails to start. Could also be a bad connection or corroded/loose wire.

 

ok car under full load everything turned on with system service light off reads 13.82v-13.89v when service light cames on it drops to 13.62v-13.67v when car is turned off battery reads 12.84v.

 

Ok, next thing is clean the battery cables to see if you can get the voltage up a little. Just looking at your numbers suggest the voltage is a tad bit low with the engine running. Maybe just low enough to trip the warning. (have radio code handy if you have a stock radio)

I would not only clean the cables where they connect to the battery but also the grounds. Pay attention to the charging wire from the alternator to the battery to make sure it's a solid connection.

If it's still low after that then check the red cable where it connects to the starter. Make sure you disconnect the negative cable so you don't get a shock.

Only after doing this free and (somewhat) easy stuff would I start thinking about the alternator. Last month I learned we have an alternator clutch pulley. Could it slip? It's supposed to slip the other way to stop belt overrun. Something to consider.

 

well I have already done everything you have suggested, when I removed the stock alternator and put in the new one last week I redid all wires to it, then the light stayed on full time with the new alternator on, then went to battery and took off and cleaned all positive and negative cables to battery and fenderwells, then took off starter and had it checked and then reinstalled it because they said it tested fine also so as far as I can tell all wires have been taken off and reinstalled cleaned.

 

Is there a way to check the alternators output voltage?

Near to my US home in Knoxville, TN there is an alternator rebuilding shop. Much cheaper and better than buying a reman'd unit from the local parts store. They can tell me everything about my alternator. You have anything like that? I'm just wondering if it's actually low output from the alternator or an overly sensitive sensor in the car.

 

no nothing here like that, but having already switched it out wth that new rebuilt alternator last week and having the same problem after I switched it out I would think that would rule out the alternator as the main culprit?

 

Just curious if you ever found out what the problem was? I'm having the same issue with my 2005 s40 t5. I'm about to take it I the dealership and I know that they will stick it to me. Please get back with me if you have figured the problem out. Thank you.

 

I am having very similar issues with a 2005 Volvo S4. We did get the warning light and have replaced the alternator, starter and the battery but the warning light will not shut off. We have tested the output from the alternator and it is in the 13+ range so no issues. The car runs fine but just cannot get the light to turn off. We have a code reader and can reset it but it will just come back after a few miles. What am I overlooking to finally get this light and warning off the dash?

 

ok here is the deal, I tried to use rebuilt alternators from advanced, autozone, and oreillys never fixed the problem I ended up buying a new one from voluparts in Atlanta factory VOLVO and it was not cheap but they had the best price I could find anywhere and they picked it up from nalley Volvo there, after I installed it and cleared codes never a problem again, I had checked voltages and everything that you had and never could find out whats wrong and I ended up having a Volvo repair man check car with his computer and he said it's the alternator and quit messing with all the crap ones I was trying to use and just buy the dang right one! SO that's what I did and fixed everything. Hope this helps but not the wallet!!!!

 

Good to know. They are very sensitive to the exact voltage it seems.

 

yes very picky I think with a volt meter it showed it should be fine but there was no other thing to have the problem I was having, so I called jessy at voluparts and he said get the factory alternator and you would not have any more problems and he was right.

 

Its not the voltage, its the communication with the CEM, which controls the alternator. A lot of aftermarket ones have this problem.

 

I came across a video where a guy states no one would figure out that it's an incorrect voltage regulator that comes with the new alternator. He said you need one that allows the computer to control... like I mentioned earlier, mine has good output, but drops and triggers volvos sensitive detection, hence the annoying light. Anyone have experience with this?

 

My 2005 S40SE 2.4 has similar issues. Three years ago, in very cold weather, and after not driving it for a few days, I took the car out and after a couple of hundred yards, all the warning lights came on, saying that the brakes had failed, the engine had major problems, the transmission and the traction control had failed, and pretty much everything else. After a matter of seconds, the car died completely. A few minutes passed and then I was able to restart the car and get it home again, but it was misfiring and trying to stall. I put the battery on charge and after that, had no further problems for a couple of years.

Then it happened again, (in much better weather conditions and after the car had driven about six miles). This time, I could not restart the car. Luckily, a passing motorist stopped and jump-started the car for me, and that again enabled me to get home. I got a breakdown patrol to check the car and after testing with a multimeter, a faulty alternator was diagnosed - the bearings on it were giving out (noisy) and it was not supplying voltage. The car was taken to an approved garage and the alternator was duly replaced.

Everything was fine for exactly six months (to the day) and then, after driving on a motorway for 30 miles in very hot weather (and having been stuck in a huge traffic jam for an hour, thus I was using the air con and fans a lot), it all kicked off again soon after the traffic got moving. This time, the car warned 'Power System Service - Urgent!' I decided to drive on as far as I could because at that point on the motorway, there was no place to stop safely. This time, the car thankfully kept running for about five or ten minutes before shutting down. Fortunately, I had just reached a safe stopping place when the engine cut out, and pulled the car over to safety with almost no brakes - and ultra-heavy steering.

The breakdown patrol tested the car with a meter and said the alternator had failed. So I had them take the car to the approved garage where the alternator was fitted (it is still under warranty) but the garage guy now says the alternator is putting out the right voltage and working correctly. He is uncertain what is wrong, but we discussed whether the battery, which is fairly old, might be not accepting a charge nowadays. The issue with that would surely be that, if the alternator was working, the engine and the management computer would not have shut down.

The electrical terminals appear clean and tight on the battery and other electrical connections. Could it be that the management computer sees a slowly dying battery as something to shut the car down for, despite the alternator supplying the proper voltage? Or is it, as has been suggested here, something incompatible about the alternator - in which case, why has it been perfect for six months since the replacement alternator was fitted?

If anyone has any further ideas on what causes this isssue, I'd be very grateful to hear about them.