2005 MKV 2.0 TDI - Pulsing lights/Fan/headlights/alternator light

[Hole]

Hi all,


Just seeking some advice. We've got a 2005 2.0 TDI Golf, low K'm <100000 with a frustrating problem.


About a month ago, we suffered an alternator failure, the pulley where the belt spins sheered off, and the entire unit was replaced.


Since then, when the car first starts, when on idle initially the battery/alternator warning light stays on until we hit approx 1500 RPM. The light then clears and the central panel (clock etc) seems to brighten up. There also seems to be a subtle change in the engine sound.


Thinking this was a faulty replacement alternator, the replacement was replaced, but the problem still exists.


There are some additional symptoms as well, in the form of the headlights, interior display, and fan "pulsing". They don't cut out completely, but they seem to dim, and the fan does the same, it seems to "slow".


I'm also thinking I can hear an engine noise change in conjunction with all this (but could be imagining it).

Aside from this, the car's fantastic!


Does anyone have any suggestions? Thanks in advance!

[Idle]

Sounds like the alternator is cutting in and out — most likely a charging circuit problem.

A VAG-Com or dealer's computer check should pinpoint it — or have a competent auto electrician look at it.

[Hole]

Thanks! Is it also possibly caused by the alternator not being a genuine VW part?

[Transporter]

Make sure you don't do more damage to the car electronic components. Always use the right alternator.

[vw1968]

Wow, i had to recheck that i didnt post this myself!!
I have a 2005 mkv 2.0tdi - bkd, Manual.
In Nov 2012 the pulley sheared off and I was left stranded, I had a new pulley and C/O alternator replaced supplied by VW.
From then on i started having problems with the battery light flashing under load.
Then the engine would cut out then restart under load going up a hill, but it did not go to limp mode.
Spent lots of time at the VW dealer trying to prove it to them there was a fault with the alternator they supplied, ended up getting them to hook up a volt meter and during a test drive found the voltage was dropping by 1volt. they supplied me with a new one and I had it fitted all was good for a while but then it started happening again and the alternator light would flash under load but no where near as bad as the previous alternator, it hasnt cut out completey yet, but when doing some spirited driving all the warning lights light up and the dash beeps for a min but does not switch the engine of, i get similar symptoms to you, the headlights, and the dash dim/pulse and sometimes the rpm is raised, restarting the engine seems to help a bit when the lights flicker. I have scaned it with my Vagcom, there are a heap of errrors regarding implausible voltages for various components around 13.9 v.(ill try and post it up when i find the logs) unfortunantly as it does not occur as often, when its taken to VW the symptons are not there and they find nothing wrong, so im stuck , i could get another alternator but i might be in the same boat, I have 1 more year on the warranty so i will try again with VW during the hot weather as thats when it seems to occur, Im in the opininon that it is the alternator as i never had this issue before replacing the alternator however now seeing somone else has the problem it could be something else. It was also suggested by an auto elec to replace the drive belt tensioner as it could have been sliping but that proved not to be it either however i did not replace the belt, I have also replaced the battery, keep me posted if you find a solution and i will also. Im on 140,000km, pulley failed @ 120k