wenzels2001

2005 Allroad 2.7T - When I press the accelerator beyond smooth acceleration the batter warning indicator light in the dash (speedometer, upper-right) will flash and when I let off the accelerator it stops. Doesn't appear to be impacting the vehicle's performance. This only happens during more aggressive acceleration, at about 1/3 to 1/2 gas pedal depression. The current battery was in it when I bought the vehicle a year ago, but appears fairly new. I haven't hit it with the multi-meter yet, but the dash gauge reads about 13.8V. Anyone else experience this or know what the underlying cause might be?

silverd2

I would suggest taking a close look at the serp belt, especially the tensioner & pulley.

Any change in the volt meter at all during hard accel and batt warning?

wenzels2001

I will watch the volt meter when the battery indicator light goes off during my next drive. I have just replaced the thermostat, which required removing the serp belt. Everything was in order after reassembly. Interestingly enough... this morning the alarm has sounded twice after parking and locking the vehicle. About 30 minutes or so after I lock it the alarm and lights start flashing. Maybe a bigger electrical issue???

danzero

Recently, I started getting the battery warning light a bit randomly (not necessarily under hard acceleration). All of a sudden the dashboard voltmeter started giving a wide range of readings with the needle fluctuating back and forth. Shortly after, my car stalled (died) while driving. I was stranded with a totally dead battery. (The battery is new.) In my case, it was a bad power cable (internal corrosion giving it high resistance) causing the alternator to work harder, essentially killing the alternator. I had to get both the power cable and alternator replaced.

Good luck!

wenzels2001

Yes, the volt meter fluctuates (outputs lower voltage measurement) when the indicator light comes on. Is there a way to test the cables? I have no corrosion at the battery and cables are tight.

wenzels2001

Okay... so I had the battery and charging system tested... everything was okay, so ruled out Battery & Alternator issues. NOW the same thing is happening... battery warning symbol comes on (only under heavy acceleration / high load) AND over the last 48 hours the security system (stock horn & flashers) has self-triggered five times... no pattern!??? It went off three times yesterday before Noon. Once last night after sitting in my driveway for 5 hours and once today after sitting in my work parking lot for 6 hours. ANY THOUGHTS?

danzero

Have you tried pulling the codes with VAG-COM? It should tell you what triggered the alarm, or at least point you in the right direction. It's possible that your two issues are unrelated (e.g. the alarm might be triggered by a bad door sensor.) Also, when your alarm goes off, does your clock reset? (in other words does it seem like the battery momentarily disconnected itself from the electrical systems?)



Regarding your battery indicator issue, in my case my battery and alternator appeared ok most of the time, but started fluctuating on occasion. The corrosion was internal in the cable (not visible at connection points.) The alternator was not able to keep up with the load when driving (i.e. heavy acceleration, or running heated seats, lights, etc.)

wenzels2001

Sounds like its time for me to invest in a VAG-COM system. Since I am new to this... are we talking Ross-Tech brand? That seems to be what I am seeing most relevantly on here. It appears the unit runs about $350, correct? Guidance appreciated, and I will purchase to dig deeper into the issue.

Thanks!

Fahrvergnugen

I appreciate this thread; I appear to have the same problem. Previous alternator has pushing 15.1 so I replaced it myself. Ever since replacement, it would lose charging with heavy acceleration. So, I replaced the belt and tensioner, same thing. I guess next I will have to check resistance on the positive to see if this applies to me.