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Discussion Starter #1
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I have searched the forum and found this issue a couple of times, but have not seen anyone with an answer on it yet. I have a 2008 gasoline sedan. The dash lights, gauges, and radio went out while driving. When the car was stopped and put in park the lights came back on. I went out to check it this morning and they were off while in park then came on and back off again. Everything works fine except for the light issue. The battery also drains overnight. I have had the battery checked and it tested good. I removed the negative cable and put a meter in between the cable and the negative post on the battery. I pulled every fuse and every relay from the panel above the foot rest and no change. So, anyone familiar with these cars know where to go from here? I'm to the point of looking for another car but would like to fix this one
 

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Parasitic draws, have been a issue for many; do you have a aftermarket stereo system? Even, stock head units; have been known to cause a parasitic issue, you might pull yours and see if the draw, goes away.

Here is a good video; going over, testing for draws:


Another thing, we have seen; is a bad ignition switch, killing power to a number of devices, they don't cost much to replace.


Here is a replacement diy:


If you have a VW specific scan tool, like VCDS by Ross Tech; many electrical issues, can throw a vw factory trouble code and help you narrow down a problem.

So, there are some things to check; let us know, what you find out and we can go from there. Thanks.
 

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Discussion Starter #3
Stock radio but I did unplug it yesterday, along with dash switches, headlights , and tail lights. I found a post last night about the scanner so I'm going to try it today.
 

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Discussion Starter #4
Pulled the battery and tray and no corrosion. Everything looks good. I did pull some codes but I'm not sure if me taking the cable off will set off a few things or not. I may not have a full description for each code. I was scribbling in the rain.
1330 sporadic power to central module too large
1331 driver side power too large
1332 passenger side power too large
1332 passenger side power too small
1672 ECM power relay surge circuit short
1379 system vtage resistance too small

A couple of abs codes came up too which I haven't had before.
495 ESP sensor short
668 Supply voltage terminal 30 short
Unfortunately, to someone unfamiliar with VW's none of these pinpoint anything. They look like they could be anything from a bad ECU to a ground somewhere
 

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You can look up the codes; on the ross tech wiki:


For example that one; references, this:

Possible Causes
  • Battery Faulty
  • Charging System Problem

    So, I would do a hard reset; of the ecu and then, possibly, run down to a auto parts store and have the whole charging system tested, confirm everything is working as it should. As you noted, the trouble codes build up; they won't go away, until you clear them. Clear, test and take a test drive, then rescan, see what comes up.
 

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Discussion Starter #6
Thanks, I've been searching on Ross and have come up with a couple to dig further in to. There is one I didn't find, 1379. But 1672 looks kinda promising, ECM relay. Some issues I've found online are running a battery down, goofy things happening with lights, etc. Looks like it's a $30 part, I'll start with that tommorow.
 

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Discussion Starter #8
I had the battery checked. Twice actually in the last month. I had 13.5 v at the battery with the car in idle and no accessories on. Typically that should be enough but he did say 14.4. v. Could possibly be a diode out in the alternator causing the draw when it's off. I'm assuming this alternator is built similarly to an older one. That was a common issue on older vehicles.
 

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13.5 at idle is on the low side of where your reading should be. At idle your car should be between 13.8-14.2. When you check the car at idle you’re actually reading the alternator output. If you have a multimeter check the alternator at the nut on the back of the alternator where the battery cable connects. Then check at the top of that same cable where it connects to the battery, the reading should be the same, if they are not you have a bad connection or cable.

If your alternator continues to read 13.5 at idle I would be thinking that the alternator is in need of replacement. What does the alternator read when you rev the engine? What does your battery read in the morning before you start the car?

Low voltage can cause a multitude of weird codes and many of yours seem power related.
 

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Discussion Starter #10
I'll have to check alt output after work if I have time today. Would a low voltage output cause the dash pod, gauges and lights, radio, ac, to just go blank? I have seen where a short in the alternator will drain the battery with the car sitting overnight but in others I've worked on and owned, it's not usually like I flipped a switch and turned stuff off.
 

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I don't know, you definitely seem to have a electrical issue, then the light issue and the trouble codes being thrown. A low voltage issue, can cause a bunch of codes to be thrown; so, it is always good to fix any charging issues, instead of chasing a bunch of symptoms, rather then the primary cause of the problem.
 

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Discussion Starter #12
First, I really appreciate all the help. I'm trying to check this thing out in the evening and still get up at 3 am for work the next day. I found two things. I couldn't reach the back of the alternator to check it directly. I am getting 13.9-14.0 at the battery. The alternator cable coming from the fuse panel on top of the battery is hot when the car is running. That tells me there is resistance. Turn the car off and it cools down. So I probably need a new cable or an alternator. I'm thinking it would be easier to remove the front bumper cover to get to the alternator.
2 I checked the relay panel and two relays are hot. Not scorching hot but noticably different from the other relays. I'm finding diagrams but I can't seem to identify the relays. They are on the bottom row. If anyone knows what they are, that would help. I'll keep looking. Thanks again
250768
250767
 

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Discussion Starter #15
Ok, that site and my phone don't agree well but best I can tell it's a secondary air pump and heated mirror relays. I've pulled both and going to let the car sit overnight. If the battery isn't dead I've found my culprit. I still think I need to get the alternator wire replaced though.
 

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Discussion Starter #17
Ok, so I am reading it upside down. It runs fine, no issues with fuel. So could just be a relay. I'm not familiar with a load reduction relay. I'll have to look it up.
 

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Looking at the fuse panel on top of your battery, the small green fuse on the extreme left is that burnt out or just not quite clear in the pic?
 

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Discussion Starter #20
Ok, finally got back to it. I changed the fuse on top of the battery. Changed the ignition switch and unfortunately, no change. Right now, car is in idle and everything looks ok. If I step on the gas, the dash lights and gauges drop.out. occasionally, the battery light comes on, so I guess it's pull the alternator and get it checked.
 
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