Hi all,
I would like to draw on your vast experience and see whether you can help me diagnose an intermittent problem which has started happening with my Euro. I will start with a few details of my car. My car is an 03 model (standard, Auto) with ~ 120,000 km on the clock.
For some weeks I have been noticing some alternator whine coming through the stereo. I initially didn’t think much of it and decided to keep driving till my next scheduled service. More recently however, I have noticed that the headlights were dimming occasionally when the car was slowing down (and especially when the transmission down-shifted), this made me more concerned. Even more recently (last week) the electronics in the car started randomly dropping out e.g the stereo would cut-out and in severe cases the dash indicators (tacho and speedo) would drop to zero. These drops would last a fraction of a second (I have yet to have the engine cut-out).
I have had an auto electrician check the car out. With his computer hooked up, he could register the car voltage dropping to ~ 4V (when the stereo etc cut-out) and then the voltage recovers (in some cases alternator overcharging to ~15V and then settling). The problem is that this seems to happen randomly and is not consistent with a fault with the alternator (the computer is not registering any fault codes). Apparently the auto electrician could not check the alternator out of the car as Honda/Denso use a strange control system etc…

I have subsequently had the alternator swapped for another and this seemed ok to begin with but after a couple of days, this fault seems to have come back! The strange thing is that if I hear the alternator whine, I can just re-start the car and it will be fine!.... The alternator swap-out has at least eliminated one possible cause. If anyone has any ideas I would be grateful!