I've had the car for 5 years now. the "pulsing" was very faint at first. map lights would pulse at idle and oddly so would the engine/transmission. by that I mean with the engine idling and transmission (5AT) in gear- D or R, light brake pressure (pedal pressed/brake lights on, but car moving) there's a noticeable pulsing similar to warped rotors but perfectly in time with the lights pulsing. rotors are in spec. for run out.

the engine runs fine and car drives great. we've put 60k miles on it without issue. however in the past couple of months i've noticed the lights pulsing is more noticeable and now all exterior lights pulse at idle. I think it's too slow to be in sync with the rotation of the alternator and there are no charging issues. which had led me to the ELD as the culprit.

the only info in the FSM about the ELD that I can find is how to troubleshoot one that has failed completely and where to find it under hood. If anyone has any experience or knowledge of these symptoms or the possibility of the ELD being the cause, let me know. otherwise, I'll post my results when I replace the ELD at the next service interval.

 

Every time I've seen pulsing lights, the alternator is the main culprit and replacing it is the only solution.

 

Yuuuuup. I think it's usually due to the voltage regulatory going out. Either way, not a serviceable part. You'll have to replace the entire alternator.

 

Read the voltage with car running.
Although a straight forward job, you can replace the voltage regulator or the whole unit. I had a hell of a time taking mine out and shoving it back in. It was jammed into the bracket tight. Couple of tricks later had it lined up and on my way bolting everything back up. If you're not handy with tools, pay someone else to do it.

 

Thanks all for the input. maybe i'll dig into this over the holidays.

I've got a pretty crappy meter so I wasn't sure it would have a quick enough response to display the fluctuation, but i may as well give it a shot. I put a decent meter on my Christmas list... fingers crossed.

I think I found the right regulator at a Denso parts site. I'll try that first since it's half the price of the cheapest alternator I have found minus the core charge!

I'm fine turning wrenches, but my electrical troubleshooting skill is still a work in progress.

 

Fixed! thanks for the troubleshooting redirect.

when i checked pricing again it was going to cost the same after core return for a reman-ed alternator as it would for the regulator+shipping. so a new alternator went on.

I'm 99% sure I've never done an alternator on a 3rd gen TL (plenty of times on a 2nd gen) so I was happy to find that it will slip out past the PS reservoir if you lift it off of it's stand.