Help Diagnosing Why My Alternator Isn't Charging - Volvo Forums

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Volvo S40 The S40 is Volvo's most affordable sedan with all the amenities of a luxury sports car. Community Links Pictures & Albums Members Search Forums Show Threads Show Posts Tag Search Advanced Search Find All Liked Posts Go to Page... Help diagnosing why my alternator isn't charging Reply Subscribe Thread Tools Search this Thread Nov 14, 2019 | 11:04 PM Share Share Options #1 Jonathan Ludwig Thread Starter | Junior Member Joined: Nov 2019 Posts: 1 Likes: 0 Help diagnosing why my alternator isn't charging I bought a 2005 Volvo S40 T5 AWD on Saturday. The battery was bad, so we replaced it. The alternator isn't charging the battery. 12 volts without load, 11 under load. ABS light is on, a whole mess of lights come on whenever I do something like turn the radio on or anything like that. Now I thought obviously, alternator is bad, need to replace it. I called a place that rebuilds alternators and he said on some cars you need to reset the computer with a scan tool because the car is still reading the old battery. Is there any truth to this? I really don't feel like spending $1000 replacing the alternator. Thanks. Reply 0 0 Jonathan Ludwig View Public Profile Send a private message to Jonathan Ludwig Find all posts by Jonathan Ludwig Nov 15, 2019 | 08:36 AM Share Share Options #2 mt6127 Super Moderator Joined: Mar 2012 Posts: 9,585 Likes: 536 From: Burlington, VT there's two common ways the alternator can fail - the voltage regulator can have a component (like a diode) fail or the brushes/bearing on the generator can fail. On some years/models the regulator is available separately for about $50. So you have a few choices here 1) get yours rebuilt or have the VR replaced 2) buy an aftermarket rebuilt unit (I'd estimate those to run $250) 3) buy genuine volvo @ ~$500 - try Tasca Parts etc 4) buy a used part (try car-part.com to search). It appears there may be a parts number break for the 2005s, so you should research part numbers for your VIN's chassis number or copy the part number off the existing unit. As to the codes, low system voltage can set some false positive DTCs that need to be cleared to turn off the check engine light (disconnecting the battery won't clear codes). Many big box parts stores like Autozone will loan an OBD2 scan tool to view/clear the codes - assuming you do the install. Otherwise a pro would simply do that as part of the job. Since you need to remove the accessory belt, its a good time to replace the belt and inspect the idlers for any play. Reply 0 0 mt6127 View Public Profile Send a private message to mt6127 Find all posts by mt6127 Nov 25, 2019 | 08:26 AM Share Share Options #3 Hudini Senior Member Joined: Oct 2007 Posts: 2,839 Likes: 17 From: Shanghai, China This model is infamous for not accepting any old alternator you put on it. This summer mine went out for the 2nd time. This particular alternator was a reman unit from one of the big chain parts stores. Since it had a limited lifetime warranty I went back and got another. This "new" one only lasted a week before the car refused to charge. In desperation I bought one off Amazon that was listed as new. It turned out to be a reman unit but it was done very well. All the plastic parts were new (not just cleaned) and there wasn't a speck of dirt. It has been working for months now without issue. Now I still had my original alternator so I took it to the local rebuild shop and had them put in good quality parts. It was still cheaper than a reman unit. Now I have a spare should my car decide it doesn't like the installed unit again. You shouldn't have to do anything but install it and start the car. If the alternator is outputting the desired voltage then all will be well. Reply 0 0 Hudini View Public Profile Send a private message to Hudini Find all posts by Hudini Reply Subscribe Related Topics Thread Thread Starter Forum Replies Last Post Changing your alternator? READ!! Carrots Volvo XC90 28 May 16, 2023 06:44 PM Alternator/Alternador Identification, Replacement procedure rloomis482 Volvo S60 & V60 5 Dec 17, 2013 09:23 PM 1979 242 DL coupe...charging problem..new batt new alt, belt? analogies Volvo 240, 740 & 940 12 Jan 6, 2013 04:41 AM alternator capacity madymo3d Volvo C70 20 Jun 5, 2009 11:04 PM voltage reg or alternator tbenner Volvo 850 10 Nov 14, 2008 09:52 AM Back to Subforum Volvo S40 View Next Unread Rebuild?! Sad day! 2.4i Thread Tools Show Printable Version Search this Thread Advanced Search Thread Tools Show Printable Version Email this Page Advanced Search Reply Closed Thread Share

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