Gundown64

So my power steering went out Saturday. I did some digging on the forums and went over to an AutoZone and had them check my battery/starter/alternator with there little gizmoo and it said that my alternator was bad. It said something about a failed voltage regulator. So I decided to replace it as I read that replacing the alternator was a fix for some people who had lost power steering. So I replaced it and started the car. No dice. Power steering is still out. I went over to the AutoZone again and had them do the same test. Again it said the alternator failed, giving the same failed voltage regulator error. So now I am confused as to what is going on and also really hoping that the EPS module is not bad as that is an expensive fix. Anyone have any idea what is going on? I plan to call the stealership and get their opinion, but I really hate to have to bring it in.

Thanks in advance!

mikellucci

iTrader: (56)

I don't know your past issue history but check the ground. If you're mechanically inclined enough to replace the alternator then I'm sure you double checked the 2 grounds in that area but you never know. Apart from that are you getting specific codes for us to reference?

VTsuckah

iTrader: (1)

Why did u think replacing the alternator would solve your power steering issue?? They are two totally unrelated systems. I have never heard of such a thing.

Have you checked your power steering fuse #18 in the engine compartment fuse box?

Gundown64

I forgot to get codes pulled when I was at the store, but the first time I went the guy said he wouldn't be able to get anything other than a basic check engine code. I'll see what I can do on that. I will also check the grounds again. Thank you.

I wouldn't say the alternator and P/S are two unrelated systems. The alternator is a crucial part of all electrical components in the vehicle, so a bad alternator could easily cause issues with sensitive systems, even if other systems don't seem to be effected.

Regardless, there are two reasons I replace the alternator. One, a little digging on the forums here and on Google brought me to two or three posts about how replacing a bad alternator fixed a power steering issue just like mine. Secondly, two separate stores did a battery/alternator check and both gave the failed alternator warning. I should mention that the car is a 2007 IS350 with a little over 100k miles and I only got the car about 6k miles ago; a prime time for an alternator to go bad. So, with these pieces of information in mind I figured there was a good chance that replacing the alternator (that I thought was bad) would in fact fix the P/S issue. Obviously this is not correct now, but I figured it was worth spending the $165 to replace the alternator instead of the $400-600 on a new EPS module.

As for the fuse, I have checked it and it was fine, but I guess it never hurts to double check.

Thanks for you help so far guys!

Gville350

iTrader: (10)

Start double-checking grounding. Also, if you know of someone else in your area with a 2IS, perhaps they will let you borrow their steering ecu to check to see if that fixes your issue.

Gundown64

Are there specific grounds that I should check or just grounds in general?

Gundown64

Update: Dropped the car off at the stealership yesterday and they took a look at it today and surprisingly they said that the alternator was bad; specifically the diodes. The alternator that I literally replaced two days ago is also bad. I am really hesitant to believe that the brand new alternator is bad which is why I turned down their generous offer of $954 for a replacement alternator that may not even fix the issue. So now I am frustrated and unsure of where to go from here. I plan on taking my old alternator that I thought was bad over to an AutoZone and have them check it and see if it really was bad. The outcome of that will answer some of my questions. I'm going to try and see if I can somehow find a EPS module maybe from a junkyard, craigslist or eBay and see if that is the issue but I am still holding onto the hope that it is something simpler and/or cheaper to fix.

Any ideas fellas? Driving around without power steering is not as fun after the first few days.

Gville350

iTrader: (10)

Take the paperwork from Lexus saying the diodes were bad back to AutoZone and have them replace the alternator. Though hard to believe the reman alternator missed Q/C for those diode, I guess it's possible.

What do you mean by "EPS module"? Electronic power steering perhaps?

Gundown64

Well see, I am hesitant to believe that the alternator is bad now. I mean, I thought the old, original one was bad because of what the stores tester said, but having it "fail" again after replacing it is unlikely so maybe there is something creating a false error. Like you said, I highly doubt the alternator would have passed Q/C with bad diodes, although there is that small possibility.

My plan is to take my old alternator to the store and have them test it. If that one comes back good, then I know that the alternator was (most likely) never the problem and the EPS could very well be shot. If the alternator does come back bad then either the new one is in fact bad (unlikely), the EPS is bad, there are other electronic issues, or a combination of the three. At this point I'm hoping I simply forgot to plug in something. A man can dream, right?

And yes, I mean electronic power steering when I say EPS. Thanks for your help so far man.

Sceanzo

autozone/advance/napa etc etc parts are bad out of the box time and time again. I work in this field, I see it all the time. If the dealership diagnosed it as a bad alternator, I would go back to wherever you picked the alternator up from and request another. Sucks you have to do the labor twice.

Gundown64

Interesting. Thanks for the input. I will see what they have to say tomorrow about the situation. Honestly, at this point I wouldn't mind having to install another alternator. That is way better than having to buy something else such as a new EPS module.

Gundown64

Well, an interesting update: I took the old alternator to AutoZone and had them test it in their alternator tester. Turns out the old alternator was not bad and is in fact good. So I am assuming that somehow the EPS module is causing the battery/starter/alternator testers to produce a false error. I guess now it is safe to assume that the EPS is bad. Now I need to find one from someplace. Hopefully I can snag one for cheap off eBay, craigslist or a junkyard. So unless somebody else has an ideas on what is causing the error, searching for a new EPS is the route I am going to go down. I guess I will also put the old alternator back in and return the newer one.

andy350

the Lexus tech guy disconnected my p/s ecu and reconnected it and my p/s light went away and it's still working for over 3 months now...
good luck...

Gundown64

Interesting. I do plan on taking out the ECU and checking it out to make sure there isn't anything obviously wrong with it.

Gville350

iTrader: (10)

^Let us know if that helps!

Did AutoZone let you return the "new" reman alternator? I guess you could just hold onto it though cuz it's bound to go out down the road sometime.

Perhaps you can create a NTB (Need to Borrow) thread from those that might have upgraded to an IS-F unit and have an older model steering ecu just sitting around. Worth a shot, and it'll be relatively cheap (shipping costs only perhaps).