Flashing battery light. NEW PROBLEMS

[Matt]

Getting a flashing battery light, goes dim then bright
So does the mileage, goes dim then bright at the same time as battery light 

Also erratic idle, fluctuates between 900-1100rpm 

All this happens at the same time. 
It's a weird one, happens all at the same time, nothing's been touched. Drove home and it did this from the next startup

Halp. Plsthxbye

[toseland]

Voltage reg fuicked?

faulty alternator?

something loading it and then unloading?



Any codes generated, have you checked the charging voltage, etc?

[Matt]

Haven't checked anything yet. It's just started doing it on the way home. Happens while driving too, can feel it giving ever so slight more power and then backing off again

[Matt]

Right so how do I check the above? I have no knowledge to hdis only gti/xud if someone could dumb it down that would be great

[BiG K]

Get a multimeter, read the voltage. Need to see what's happening with it to diagnose.

[Poodle]

Should be charging at between 13.8 and 14.2 volts, can get away with .2 either side as you rev it up and down. Still, you shouldn't see much change regardless of revs. If that's fine then check the resistance on your main alternator-starter-battery lead and your earths, should be less than .2 ohms. Don't forget to check your battery terminals are tight and secure.

[cully]

check the alternator connections had this on my HDI the battery terminal on the alternator was burned off

[Matt]

Got it, will be going to buy a multimeter in the morning. How do I read? Put multimeter on each terminal?
I'm crap with electrics haha

[Matt]

Will be taking a look at it today wish me luck

[pug306driver]

take your time, read the dmm instructions and be methodical. write tests down for data.

[Matt]

Okay an update.

Whilst driving today all symptoms stopped. Apart from a very dim battery light.
I then entered a dual carriageway and accelerated quite hard to 70
Then all the warning lights came on: abs, handbreak, battery (still dim), air bag and seatbelt lights.

Then one by one they turned off. And I was left with no lights.

Did a corner and then the battery light returned but really bright

Wtf did I do?

[ginge191]

Sounds earthy to me...

[pug306driver]

have you used the dmm and check the earths/wires

[Matt]

Dmm? What's that?

[andywhy]

Digital multimeter. Does sound like an earth or other connection issue. I'd check everything is tight on the alternator and that nothing is worn or frayed.

[Matt]

Well, the battery light has been on since yesterday. I drove it 14 miles to work and back and then all the warning lights started coming on.
CD player would switch off every time the wipers kicked in. Mileage dim. Clock dim.

Got home
Sat in the car, turned it off. Turned it back on and nothing. Dead battery.

So think it's pretty safe to say the alternator has gone? Or could a dodgy earth cause it to not charge?

[Jonny81191]

I'm saying dodgy earth tbh

[Matt]

Even with the fact the battery is now dead? I would have said that was the alternator packing up no? Not charging the battery?

[Xsikid]

Even with the fact the battery is now dead? I would have said that was the alternator packing up no? Not charging the battery?

For what a second hand alternator cost maybe put one on to rule it out bud?

[andywhy]

Even with the fact the battery is now dead? I would have said that was the alternator packing up no? Not charging the battery?

Dodgy earth would also prevent the battery charging properly. The charge light coming on is an indication of little or no charge going into the battery, but yes it is possible. Don't rule anything out.

[BiG K]

I'm going with a dodgy earth cable too. As you have a multimeter, pop it onto the "Voltage" or "V" setting, there will be some numbers on that section, 20 will be fine. Red = Positive, Black = Negative or Earth on the battery. What does it read?

Think of electrics as a circuit, electrons which is the "energy" is the bit that flows. So it comes out of the positive terminal and flows into the negative cable. If there isn't a return path, it won't start as the electrons can't get to the negative terminal.

[Poodle]

Just get on with it and actually test some stuff dude, stop being lazy.

[Matt]

Well, I tested it all.

It was the alternator after all. A few thing stopped working like Windows and rear lights, so checked all earths etc, but it turned out that was blown fuses. But they sent me looking in a different direction. Either way it's sorted now

And has been sold and is looking great

[ginge191]

Well, I tested it all.

It was the alternator after all. A few thing stopped working like Windows and rear lights, so checked all earths etc, but it turned out that was blown fuses. But they sent me looking in a different direction. Either way it's sorted now

And has been sold and is looking great

... the rallye is sold??!!

[Matt]

Oh no, this was on the misses hdi before she got the 206

[C2K]

This is classic signals of a faulty rear wiper relay, bridged internally by corrosion. I suffered this on my hdi many years ago. Knocks the fuse for the electric windows out, when I replaced the fuse the wiper tried to start and immediately popped the fuse again.