PMaisey

Final Update: OEX, who are the distributor for the alternator I installed, advised there was a later version of the alternator I had been supplied by Repco which addressed the issues I was having. They had replaced the regulator in this later alternator with an updated version based on the genuine Lexus regulator. They airfreighted me a replacement overnight, told me to bin the old one and I installed the new one the same day. Have been driving for 3 days now and has not missed a beat. So for me it was worth the inconvenience of having to put up with the pulsing for a short time and being able to resolve the issue for a total cost of AU$420 versus Lexus quote of AU$2700. I would suggest to Alex who started this thread, go back to the installer, find out what alternator was installed, and if it was an OEX, have him contact the distributor and get them to supply the later one. The only issue should be the time to replace which based on how long it took me to remove and install, should be a maximum of 2 hours or you might want to push for no charge. Anyway, all is well, that ends well. I'm a very happy camper. Cheers Paul

Yep, thanks Vlad, that's very helpful.

Here's an update: Problem reappeared today and after a bit of research I found the following: OEX RLO and S Alternator Regulator Function Tester In a world where vehicles are getting more and more complicated, picking the right alternator can be difficult. A problem amongst many Toyota Camry and RAV4's that use the 2AZ-FE engine, there are two different types of alternator, based off the regulator function, but their plugs look virtually the same. One type of alternator has an S function, also referred to as "Sense" and one is "RLO" which is "Computer Communication". Long story short - it causes all sorts of headaches ordering the right part for the job. OEX have taken the guess work out of it with a simple tester. The ACX6250 simply plugs into the harness which would normally plug into your alternator. You turn the vehicle to ignition (vehicle without starting) and with the flick of a switch to identify the regulator function. The alternator I installed was an "RLO" type and I am assuming I need the "Sense" type. Will confirm with the distributor tomorrow, but it would appear, given the symptoms, that will be the issue. My symptoms are now identical to Alex in the original post and by switching the lights on (and creating a load on the alternator) the problem goes away. But it seems if you have the lights on when you start the car, you can also get the issue. The voltage bounced between 13.05 and 13.95 when the issue is present, then flattens out to around 14.20 when it goes away. Keep you posted.

Thanks for the heads up. No, was not aware of the Techstream product, but will investigate and see if it could be useful in the future. With my current issue, there were no error codes thrown up so not sure if Techstream can go beyond this level to id issues? As mentioned to Steve above, the car has been running faultlessly after some tinkering today, so we'll keep using it and see if the problem reoccurs. Fingers crossed. Cheers

Hi Steve, Thanks for your reply. The following data is provided as suggested: No Load Off: 12.97 V Idle: 14.27-14.28 V 1500-2000rpm: 14.30-14.31 Load - High beam headlights, aircon and fan on full, radio on Off: N/A Idle: 14.13-14.15 V 1500-2000rpm: 14.21-14.24 V As an aside, I have tried to replicate the pulsing this morning and have been unsuccessful. Have done all the things I would normally do to make it happen, but not playing. The only things I have done are to removed all the engine covers, disconnect the cable retaining bolt and bracket which attaches to the engine for the main positive lead (it did free up the tension on the alternator connection), and removed the rubber sleeve which covers the positive alternator connection. When I originally fitted the alternator, I did break off a bit of the plastic which sits under the positive connection on the alternator and I'm not sure if there may have been some arcing when under the rubber sleeve? Long shot, highly improbable, but who knows. Also maybe the plastic engine cover was pushing on one of the connections underneath it and creating an issue. Or maybe the retaining bolt and bracket were creating an issue. A bit of straw clutching going on here 🤪 but nothing else has changed. Anyway, I will leave it in its current state and we'll keep driving it and see if the problem returns. Then I can do some more tests. Hope the figures above are what you're looking for. Love to hear you thoughts. Cheers

Hi there, my first post as well. I have exactly the same issue with my wife's 2010 IS250 in Perth, Western Australia. First sign something was not right was the battery warning light coming on briefly, then going off. Same with the alternator light. A check of the battery showed it was not holding charge so that was replaced. During the replacement process, the alternator output was checked and it was about 12.5 volts regardless of the revs, so obviously the output was not sufficient to maintain the battery. There were no error codes recorded. I subsequently ordered a replacement alternator from one of our aftermarket suppliers (Repco) and fitted that. It was a bit of a pain and was spread over a couple of days, so the power to the car was disconnected during this time. The pulsing started after this time. After trying a number of things, I accepted defeat and after speaking to the local Lexus service manager, I put it in, based on his recommendation, to have the engine decarboned. Not an inexpensive exercise at $880 Oz. The ECU was also baselined at this point and when I picked it up it seemed to have made a difference. Unfortunately, it was back again the next day. Spoke to Lexus again and arranged to drop it off for further investigation. They range back to say they thought it was the new alternator which was creating the issue. They tested it by running the car with it pulsing, then connected a second battery to the car battery (via jumper leads) and the problem went away. Disconnect the second battery and problem returned. As we are thinking of selling the car, and the replacement genuine item is $2,700 Oz to supply and fit, I said I would give it some thought and let them know if I decided to go ahead. They said the output from the alternator was like a staggered output sort of like this with ups and downs. ___l----l____l They said that the genuine item was more like a sine wave ~~~~~~. I haven't had a chance to replicate their testing with the second battery but will look at that in the next day or so. To me the variable output seems to be a function of the regulator which is built into the alternator, but I am no expert. It would seem strange that would be faulty in a new alternator, but I'm sure these things happen. This is the unit I installed OEX Alternator 12V 150A Denso Style - DXA4049 If anyone has any suggestions or comments, I'm all ears. Cheers Paul