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I'm not sure what the trick to those ECU clips is either? Mine are all messed up, but still seems to hold in place fine afterwards.
After you break that nut free, it should spin free by hand. If dropped, it will likely end up on the plastic undercarriage plate that needs to be removed when changing the oil. I just maneuvered my arm down and in from the right of the headers the same way I was able to finagle the wrench in to place.
Thanks - I searched around and found another thread (may have been a 250 thread) and a poster mentioned getting it by hand. It was hard to get a wrench on the nut and since there is such little space, once it was on, it was hard to even tell since I was only able to move the ratchet like one click...
Your input and the OPs pics were greatly helpful! The difficulty of getting to some of the spots and maneuvering around is a bit understated - the OP makes it look/sound so easy! haha
This is a great write up, and it helped me a lot with this whole process, but just wanted to add a few notes for anyone who is doing this as it can be a real pain.
First is with the clips that hold the ECU in place from the side. The white body has square cut outs that the black prongs from the housing go through. I mangled up the plastic pretty good on this prying at it with a small flat head before I was able to remove it, and even after getting it out, do not know how you would go about pressing those clips properly to just let it release?
Second is after you remove the 2 bolts from the front of the black ECU housing and the nut from the back, you literally have to PULL the hell out of that thing to get it to come free. The front right corner towards the bottom has an air duct that protrudes down, and it has a little extrusion on the side of it that kind of locks it in place pretty well when mating it with the lower port.
Lastly, the issue with the hidden bracket that is back behind the alternator itself which is an absolute pain to get to! I was able to get to it with a ratchet wrench, 3 inch extension, and a deep well 12mm socket. Not sure if there was a different bolt holding it on his car, but the nut was not a 10mm on mine. It takes some tricky moves to get your hands and wrench down there properly, but it is possible. When I had it out I took some pictures, so I hope they will help.
After going through this and reading other reviews about this, it does not surprise me that some dealers are charging just under $1K for this job with parts, but if you are willing to do it and save yourself 800, then it's probably worth it. Good Luck!
Brilliant write up to the orginal poster!!! Can't thank you enough for this, you just saved me roughly $600.
With regards to the bolt at the back of the alternator (was a pain getting to) my bolt was also a 12mm and here i was struggling with a few different size 10mm sockets trying to figure out what im doing wrong as it was pretty awkward getting to it. here the few pics i took during the mission.
Took me roughly an hour & a half to get it out...Oh btw, my car is a IS250 but it was exactly the same as the IS350 except for that 12mm bolt i mentioned above.
with regards to the guys that were struggling with the ecu clips, i used a precision flat head screw driver and rather than pressing the black clip inwards which doesnt seem to budge, i rather pulled the white plastic over the black clip instead as the white plastic is alot more flexible than the black plastic from the casing.
I seriously can't thank you enough for posting this. once i saw this i was able to get it out with very little trouble and it went in super easy. thanks again!!!
Thanks for the write up. The pictures were very helpful. I have installed the alternator and now the car will not start. I have charged the battery and cannot get it to turn over. The lights all come on, but when I push the button nothing happens. Anyone else have this issue?
Great DIY ..I could not have changed the alternator on my Lexus Is 350 without you ...so thank you!
I will only add that my bracket behind the alternator was also a 12mm. For the people who changed their battery and it won't start. It happened to me ,but I did this and it started up.I made sure my hood was closed I got in the car put the key fob up to the start button while my foot was on the break. And shifted from park to drive 2 times. Then I got out of the car and opened and shut every door then I unlocked the trunk with the ACTUAL KEY. After that I got back in the car held the fob up to the start button for like 10 seconds buttons facing towards me, foot on the break. The I let go of everything and tried to start it normal and it worked, it was like a security thing..there are also some info about this in the owners manual.
Great DIY ..I could not have changed the alternator on my Lexus Is 350 without you ...so thank you!
I will only add that my bracket behind the alternator was also a 12mm. For the people who changed their battery and it won't start. It happened to me ,but I did this and it started up.I made sure my hood was closed I got in the car put the key fob up to the start button while my foot was on the break. And shifted from park to drive 2 times. Then I got out of the car and opened and shut every door then I unlocked the trunk with the ACTUAL KEY. After that I got back in the car held the fob up to the start button for like 10 seconds buttons facing towards me, foot on the break. The I let go of everything and tried to start it normal and it worked, it was like a security thing..there are also some info about this in the owners manual.
I just took mine out and replaced the contact/brush ring. Great write up my friend. Total job took 1.5 hours. I had the start issues as well and thought I had drained my battery. Got it going now. I used this stuff they call num num inside my 12M socket. It is like a chewing gum that hold the nut in the socket. I used this to get the bracket nut back in behind the alternator.
I recently had to undertake the hell that is replacing the alternator in my 2007 IS250 AWD. The voltage regulator went out somewhere along the line, taking the battery out with it (FML) at about 120,000 miles - from what I could tell, it was the OEM alternator (I'm the third owner). For about a week or two prior to the repair, there was a sort of "burnt electrical" smell when I would exit the vehicle, and while sitting at a light, my GPS went off on me until I was able to get the RPM's back up. It was not until the day it died on me that the battery light decided to come on, and I barely made it to the AutoZone parking lot before I lost my power steering. I had AutoZone order a remanufactured one for me to pick up later that same day, as it is not a common item that they keep in stock. After removing them from the vehicle, I took the alternator & battery to several Advance Auto Parts stores, one Pep Boys, and two AutoZone stores, all of which had a hell of a time trying to figure out how to get the right code to test this alternator for some reason. Only the PepBoys, and one of the Advance Auto Parts stores succeeded after trying many times.
Anyhow - it's a tricky little process, but it's doable. I cannot thank the OP & contributors enough, as this thread was a HUGE help to me. I curse the engineers for all of those pesky clips, and for the evil bastard that decided to throw that bolt behind the alternator, as I had a hell of a time locating it, and getting it off. In the end though, putting everything back together was no problem - just be sure to keep up with what bolts go where, and you should be good. Removing it took me about four hours alone to figure it all out, and getting it back in & back together took about an hour.
Just curious if going up from under the vehicle would have helped with getting some of the bolts located and off and pulling the alternator out. I'm about to undertake this project myself and am looking for any insight.
Thank you for the write up and all replies. I tackled this myself tonight. 2007 IS250 AWD w nearly 220,000 miles. I am the original owner and this is the first and only alternator I have ever replaced.
Also...
Just curious if going up from under the vehicle would have helped with getting some of the bolts located and off and pulling the alternator out. I'm about to undertake this project myself and am looking for any insight.
I don't think you could reach anything from under the car. My 'hidden' nut was also 12mm. I was able to extract is using a deep socket with a short extension.
I followed another DIY alt replacement. I beefed up mine to a 250Amp. The only thing that was difficult was getting the nut back onto the alt bracket. I was trying and trying from up top but decided to go under the vehicle. I kept dropping the nut and it got lost somewhere. It was MUCH easier to screw it on by hand and then use my 1/4" drive.
I just wanted to say if it wasn't for this post I would have been able to take out the alternator. Thanks guys you saved me a lot of money. I was able to get a OEM denso alternator for 130. WIN lol.
The bolt on the back of the alternator almost made me call it quits. That **** was had to get to I had to go out and buy a extension.
Ever since i pulled the alternator the car was been very sluggish. When I initially press the gas it hesitates. I never experienced this ever in the car until i changed the alternator. Feels slower.
12-30-14, 05:27 PM
Fantastic post!
