sl90

Battery and/or alternator problems?

Recommended Posts

Hi all,

I was recently driving through town when I suddenly had both the battery and ABS warning lights appear on my MK6 1.4TDCi. The car seemed to be driving fine but I pulled over in a nearby car park anyway. I turned the engine off and when I went to turn it back on again all I got was the clicking noise. I was able to get a friend out to give me a jump start and managed to get home fine (battery warning light still on). 

When I got it home I left the car to idle in the driveway for around 15 minutes. The car never lost power during this time and the ABS and battery warning lights would come and go intermittently which I found a bit strange. I took the battery out and let it charge overnight. 

The next day I took the car out for a drive and it seemed to be working fine until around 10 miles down the road when the ABS and battery warnings came on again. Not long after the car came to a stop and lost absolutely all power, hazards etc not even working. 

I got another jump start and managed to get the car home fine.

I replaced the battery today and still have the battery warning light on the dash. I was told to check the voltage with the hidden dash trick. While the car is turned off it reads 12.6v and with the car idling it reads between 12.4 and 12.6.

Does this sound like an alternator problem? Are there any tests to perform so I could narrow the problem down?

Sorry for the long post, I thought it would be helpful to give as many details as possible as I have no idea when it comes to cars!

Thanks.

 

Share this post


Link to post
Share on other sites
 

5 hours ago, sl90 said:

While the car is turned off it reads 12.6v and with the car idling it reads between 12.4 and 12.6.

Does this sound like an alternator problem?

Yes!

Just try the same battery voltage test with the engine at about 2000 rpm. It needs at least 14v to charge the battery. If the battery is good, but in a low state of charge, it may take quite a while (several minutes) for the voltage to rise. But if possible use a meter on the battery terminals. The dash voltage is often inaccurate, due to voltage drops in the system wiring.

You could also turn the headlights on while the engine is running. At 2000 rpm, there should be hardly any drop in voltage.if the alternator is ok. Even at idle, it should hold at 13v or more.

If the battery warning light is on, and it never gets to 14v, then it is either alternator, or the connections to it.

Check the fat wire from the battery +ve to the alternator, and the fat wire from battery -ve to the engine (usually near the starter motor.) Make sure they have good, clean, tight connections. There are also three small wires from a plug on the alternator, you could try removing, looking for corrosion & replacing it. But most likely there is an alternator fault.

 

Share this post


Link to post
Share on other sites

Yep thats an alternator problem - when the engine is on it should read 13-14v, as TDCi-Peter has mentioned, check the wiring as well, it would also be worth swapping out the aux belt when the alternator is swapped out as well as any tensioners etc.

Use the voltage directly on the battery rather than any other method as its more accurate.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.