1uzae86

Ok so I have a very annoying electrical issue that has arisen in the last couple weeks and seems to slowly be getting worse.

Symptoms:
-Factory Nakamichi stereo cuts out randomly with occasional loss of power (witnessed by power antenna retracting)
-headlights and any lights on dim
-parking indicator lights dim and brightness pulsates if turn signals are on or I pump the brakes
NEW symptoms:
occasionally when rolling windows up/down or opening/shutting sunroof and the action finishes stereo now occasionally cuts out or audio level diminishes significantly.
a couple days ago I did find what appeared to be a ground wire for the remote trunk opener that was broken, patched it up but symptoms are still persisting.

I had my alternator tested earlier today (9/18/14) both with the hand held tester thingy and old school method (pulling + terminal off), after the electronic test was done and the results printed out something caught my eye and the person who did the test, on the result paper it said "ripple detected" does anyone know what that means?
Battery was bought 2-3 hours before I got the car (5/714), alternator was picked up and installed the next day (5/8/14)


At this rate I'm cutting my losses, I'm good with wiring but I don't have the time to put the car down for inspection of the electrical system and possibly dash harness visual inspection

Yamae

The link below shows the waveforms of an alternator and the yellow lines are the ripple part.
http://jaguar.professional.org/Alternator.php

I worry that your alternator has some problem rectifying the 3 phases AC. Probably rectifying diodes are not fully working properly and the ripple is bigger. If so, you will have undercharging problems as you mention.

fixmiester

[QUOTE=Yamae;8717919]The link below shows the waveforms of an alternator and the yellow lines are the ripple part.
http://jaguar.professional.org/Alternator.php

I worry that your alternator has some problem rectifying the 3 phases AC. Probably rectifying diodes are not fully working properly and the ripple is bigger. If so, you will have undercharging problems as you mention.[/QUOTE

That's a nice link to basic alternator operation and useful checks with a scope or DVM. The waveform pictures do a good job of explaining 3 phase rectifiers, but he did make a mistake in the last picture showing a "shorted diode" ; in that case the yellow waveform (composite voltage) would have a negative excursion going below the zero volt reference. His last picture is instead identical to the previous one showing an open diode. But he did a good job otherwise. Thanks for sharing.

simrx3

check battery connections..

ie remove clean the clamp and post with a wire brush and reconnect..

also do this to the body earth connection from the battery and the engine block earth..

this should solve your problem

1uzae86

Fortunately I didn't need to do any terminal and earth connection cleaning, I had the alternator put on a test bench and the Diode came back bad. Got it replaced and so far the issues are no longer present, I believe when I put power steering fluid in the pump to try and locate the leak the PO told me about, it leaked enough to cause the diode and possibly other internal issues.

But sadly due to my financial situation I can longer afford to keep my 91 LS400 and have been offered a 2001 Honda Civic 5spd and cash, I am taking the offer because I need fuel economy for how much city driving I do looking for work. I will be back to the Lexus scene when my financial situation allows me to do so. Thank you guys for your help since I purchased my LS400 back in May, I have learned quite a bit and still have learning to do!