Just trying to gather some ideas on the strange problem I have with the electrics on my B5 RS4. Fitted a brand new Valeo alternator last July after the old one packed up, sourced from a rewinds specialist close to where I work. At the same time, while the car was out of action at this time, I had the battery on trickle charge for a few hours over a couple of nights to get life back into it again.
Now the problem I have is, and it doesnt seem to be consistent every time is that all the lights, both interior and exterior and the DIS display start pulsing from time to time, particularly at idle.
In its normal course of this action, the pulsing will be at around 1 second intervals and may last about 2 minutes then return to normal but then it returns as a more faint high frequency pulsating. It will disappear then one the engine rpm is taken above idle but sometimes it wont either. Sometimes it will start as a high frequency ripple and then slow down even if the engine speed doesnt change. Sometimes its quite worse than others irrespective of ambient air temperature, time of day or engine temperature. Putting on or taking off an electrical load doesnt seem to affect it. Tonight on the way home from work at 70mph on the DC, it was pretty noticeable also.
Its beginning to bug me now as to what it might be, suspected the alternator again but the problem isn't always the same to nail it on that. Was thinking of changing the battery in case there was a bad cell in it but the car starts and charges OK and have no problems starting it if its left up for a week or more. Had some electrical test equipment on there to measure the alternator ripple and the condition of the battery but nothing showed up of any concern. No fault codes showing up either on VCDS in relation to the electrics.
Has anyone experienced similar problems in the past or any idea where I should look to try get to the bottom of this??
Any help appreciated!
Tom.