Throbbing / Pulsing lights

P

paulr187

New Member
Hi guys,

Looking for some help.

Recently, my 150 Highline has had an issue with the lights pulsing, bright then dim, constantly. Also, when the ignition is turned off, the infotainment system turns itself off due to ‘insufficient battery charge’. I’m also not sure that my start/stop system is working either, or it hasn’t since this problem developed. The van flashed an error up once a few weeks ago saying ‘brake issue’, but that went away immediately and hasn’t returned.

It been into Vw twice now, they have charged the battery two weeks ago and checked the battery, it is completely fine.

Took it back in this week for more fault finding, and they have gone as far as charging the battery again, that they have already proved is completely fine. I feel like they are delaying as it is still under warranty.

My thoughts are alternator, or voltage regulator issue, but is there a way that I can test these? Not sure with it being a smart alternator.

Has anyone else had similar issues???

There is no split charge system etc, it’s just a standard Kombi with a couple of extra LED lights in the back.

Thanks all
 
It’s also affected by revs, increase revs to around 2000, then when I take my foot off the accelerator, the light will dim for a second or two.

Like I say, battery tested and proven good.
 
I would be checking all the battery and alternator connections- positive and earth. There is a known issue with a corroding earth strap connection.
After that I would start to suspect the alternator itself.

Pete
 
Do you get a pulley squeak when cold? Also, check the alignment of the auxiliary belt tensioner - is it fully in line with the belt, or is the belt running off the side slightly?

I used to get a squeak from that belt when cold (battery low and alternator more difficult to turn) and it was slipping slightly on the alternator as the tensioner wasn’t fully effective. This caused the battery to not charge as well as it should. Fitted a new tensioner and belt.

May be worth a look.
 
Can you get a video clip of if.....

Post a link to that here for us to see, and also use to show the garage.

Connect up a volt meter and video the voltage readings too.

Sounds electrical to me, there should be fault code stored for T6 onawrds,

What's the van spec and got a few pics?
 
Thanks guys.

Van spec is a 2016 150HP Highline Kombi, Indium Grey for what it's worth :)

So, the facts so far

No pulley squeaks at all when cold,

Lights are pulsing high then low when started cold, and seems more frequent now.

When the van is turned off but key left in ignition (where infotainment system stays on), the infotainment system turns off due to low battery (the battery was holding over 12V when this happened), so it's a signal issue in oppose to an actual low battery voltage.

When I rev the van up to around 2000 revs, as the revs drop the lights / power dips but then returns to normal when the van idles.

The stop/start system appears to not work now (guess it's because the conditions aren't right because of the issues above).

Battery is holding a solid 12.4 to 12.7 volts when turned off.

Earlier I ran the van with the meter attached, the battery voltage increased and was showing between 14.2 and 14.5 which suggest to me that the alternator and the voltage regulator are doing their jobs effectively. Thoughts?

I have checked continuity between the battery ground terminal and the chassis to prove we have a good ground, it appears all well.

All stuff I'd hope VW would do under warranty in oppose to just charging my battery twice and saying its a good battery.

The VW guy tried to tell me it was the additional items on the battery, which is bollocks. There are 6 LED lights on the interior light circuit (on a switch which is always off), and there is a USB port attached to the battery for the rear of the van, this is fused at the battery and has never been used all the time I've had the van. I've removed the fuse to write off this being the cause of any grounding issue.

My thoughts are that this is pointing towards a short somewhere, but if you guys can give any pointers on what and where to check then that would be great. I'm handy with a fluke and have a background in Marine Engineering, so send any thoughts. I want to go back to VW armed with as much information as possible on Tuesday.


Will post videos and pictures of the van soon. I love it :)
 
It really feels like an alternator issue then.
Do you have an oscilloscope that you can use to see the volts rising and falling (a DVM won’t help here).

Also, it would be worth removing any earth connection and cleaning it up thoroughly. It might be fine at low currents, but not high.

Also, if you have just sidelights on, do they (and the tail lights) pulse ? ie does this only happen when more current is being drawn ?

Pete
 
I wouldn’t dismiss the voltage regulator, only a choppy voltage can cause things like that and remember the regulator only feeds equipment and not primary stuff so it won’t affect engine ancillaries etc
 
paulr187 said:
Appreciate that mate, but what's the rationale behind your thinking? Surely VW's check of battery should give confidence it is fine? Twice :)
Click to expand...
Did they do a deep discharge test? It’s one thing putting a voltmeter across the terminals, another thing entirely when under load.
 
Can I throw in a couple of random thoughts?
Have you checked all of the earth straps between battery - chassis - engine?
Are you measuring the voltage between the +ve terminal and chassis or -ve terminal? If the latter try the former.

Ditch the digital meter and use an analog one, that will show voltage fluctuations where a digital doesn't.

A scan will tell you what the voltage was when the infotainment turned off.
 
All,

Firstly, thank you all for your input on this.

@Jimmmmy 's post about changing the battery got me thinking, even though the van has spent 4 days with VW for them to tell me the battery is completely fine (assuming they load tested it etc), I wanted to check my van with a different battery.

I drove across to the coast to a friends house today who has the same spec van, swapped over the batteries, and surprisingly the issue has completely gone. All symptoms vanished, van completely back to normal.

I have lost what little faith I had in VW servicing, but am over the moon to have this issue resolved. New battery on way.

Thanks again fo your help fellas

Paul
 
You have changed the batteries back and the problem has returned?

i.e. not fixed it by loosing and retightening the battery clamps!
 
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