KahnBB6

iTrader: (5)

I had my Mirror Control ECU die on me last month and I bought a new one to install, and then I learned how difficult it would be to replace it. I finally decided I had to get this over with. Here's how I was able to do it.

Disclaimer: This is an explanation of how I was able to change out this ECU. Due to the complicated physical nature of how to actually get to this thing while being able to see what you are doing I take no responsibility for anything that happens if someone takes this advice.

Sorry to state that but I can see how someone rushing this process or just having a bad back might want to consider the steps of this DIY carefully before proceeding. This is the only way I could figure out how to do it myself and I absolutely took my time prioritizing safety and very slow and controlled body movement in and out of the footwell over taking as little time as possible.

Now with that out of the way:

Most of it is easy... except for ONE sadistically placed upper screw that seems impossible to get at.

It is not, in fact, impossible and nor do you need to dismantle your entire dash to remove the top screw holding the ECU in place. However it is still a hellish chore all to get to one stupid 10mm screw.

Before going into it I found a thread on another Lexus forum suggesting the best way to get to it was with a socket wrench, long extension, then a swivel adapter, then a stubby 10mm bit. The radio and center console must be completely removed and the extension has to be fished through a specific pathway from that now open area where the radio and console used to be. Taking any more of the dash out will not help and there is no good way to get at that 10mm screw otherwise. The lower Mirror ECU screw is easy with a 10mm closed end wrench (or one with an internal ratchet if you prefer).

A screwdriver or thin open ended wrench is then needed in order to fight with and prod that lengthy socket extension and swivel into place onto that awfully placed bolt.

Additionally, with the Mirror ECU disconnected and with the lower 10mm screw removed you will be able to *gently* move the ECU and thus the top screw mounting area around a little. You will have to combine your fight to get the socket angle in place with pushing on the ECU a bit to get everything to line up (it took me almost two and a half or three hours on and off with much trial and error).

Also, wear some goggles or closed eye protection. A lot of random debris will probably get into your eyes because....

You will need to do this on your back, laying down with your head in the footwell looking up into the ignition switch area. Push the driver's seat all the way back and BE CAREFUL OF YOUR BACK WHEN DOING THIS! MOVE SLOWLY AND DO YOUR BEST TO KEEP YOUR FRUSTRATION IN CHECK. A STUPID BOLT PLACED IN THE WORST POSITION POSSIBLE IS NOT WORTH PULLING A MUSCLE OR OTHERWISE HURTING YOURSELF. PACE AND MOVE SLOWLY INTO AND OUT OF THIS POSITION WHEN YOU NEED TO ADJUST SOMETHING, GET ANOTHER TOOL OR INSPECT ANYTHING FROM OUTSIDE THE FOOTWELL.

IF ANY OF THIS RAISES YOUR CONCERN, KNOW THAT THE ALTERNATIVE METHOD TO REMOVING THE OLD MIRROR CONTROL ECU IS TO GET YOUR REPLACEMENT IN THERE ON TOP OF THE OLD ONE AND SOMEHOW SECURE IT IN PLACE. I DID NOT WISH TO DO THIS AND SO I DID IT THE HARD WAY.

Place a bright LED light source (I used my smartphone) directly on your lips for proper light to see what you are doing and to have your hands free to work. I am NOT kidding... put your light EXACTLY there shining upwards to be able to see properly. Use a forehead lamp on a strap if you think it will give your light a better cast but this is the only lighting angle that worked for me.

^^ Breathe. Have zen-like focus. Do not be deterred. You WILL be frustrated. Unless you happen to get really lucky on the first try. Getting yourself into position, removing the lower 10mm screw, disconnecting the harness Mirror ECU harness wires, and even getting the socket extension relatively close to the screw are all easier than actually getting your socket extension lined up and ONTO that screw and staying there firmly enough so as not to wobble off or strip it. Once you're in there it comes down to trial and error and finally being firm enough to keep tight contact on the screw.

When you do make contact, keep pressure on your socket wrench on one end and push on the Mirror Control ECU a bit with your other hand. Be firm. You do not want to strip this 10mm screw because even though it has also phillips screwdriver marks there is no way you will be able to use them.

Press hard with the long and extended socket wrench to keep pressure and you will break the 10mm screw loose. Keep winding and it will fall out near your face within a few ratchets.

NOW you can remove the Mirror Control ECU and replace it.

Put your replacement ECU into place where the old one was, insert the little tab (you will see this when you do it), plug in the ECU connectors and THEN align the first 10mm screw location back into place and get it in there. Use a dual open end / closed end 10mm wrench for this and get it tight.

And now you can forget about the top 10mm screw from here on out. Never replace it. The ECU is not going anywhere with the one lower screw, the upper tab inserted and the two harness wires connected. Would be nice if it were easier to replace but... it isn't so good riddance to it.

Now button everything up, replace your center console and radio and enjoy working side mirrors again!

For reference, here also are the TSRM pages that pertain to removing and replacing the Mirror Control ECU. Notice how Toyota completely glosses over the accessibility of the upper 10mm screw.

TXMAG

iTrader: (1)

Nice write up Craig. I hope I never have to use it!

I loved the process in the manual for this being (3) steps. "It can't be that bad"... Been there, done that on soooooo many cars in my life.

t2d2

iTrader: (8)

Man, they really do gloss over it in the manual.

For small projects in that area, I usually just contort around the seat. Any time it's expected to take 30+ minutes, and especially something hellish enough to take 3 hours, I would recommend removing the seat. We've got some seriously plush carpets in these cars, so stretch your feet out and work comfortably!

Duck05

My mirrors have never worked since getting the car back from the son in 2011 and he does not recall when they stopped working. After checking out every other possible reason (switch is bad, no power, etc...) why the mirror controls did not work the Mirror ECU was the next step...

Well, after seeing the cost of a new unit, there were more reasonable sources on eBay and was going to try one of those until I read the various stories of replacing this and the "famous" 10mm bolt .....

One write up I read had said it (the 10mm screw) could be accessed from the top if you removed the instrument cluster. (That could be wrong or wishful thinking,) In any case, suffice it to say I am perfectly happy with manual adjustments of the mirrors for now....

Never has there been a car I have read about with so many "ECUs" spread all over the place.... (main ECU, mirrors, fuel pump, seats)


Thanks for the write up and advice... At some point I may tackle this challenge and will read/research anything everyone has to offer....

t2d2

iTrader: (8)

...ABS/TRAC, tilt/telescoping steering wheel, cruise control, power steering, remote unlock. Just to name a few.

There's something to be said for division of labor, so the whole thing doesn't have to be replaced if one component fails. But they drank a bit too much sake when they laid out the SC... There are redundant wires running every which way, ECUs tucked everywhere imaginable, and a fuse panel layout with random assignments that might as well be written in hieroglyphics.

KahnBB6

iTrader: (5)

^^ They definitely gloss over how to remove the upper 10mm screw. Hardly addressed other than a note to refer to another section to remove part of the lower dash on the driver's side.

I thought about removing my driver's side seat. I've done it before in the past and in my case I have a lighter Supra MKIV seat in there which is not so difficult to lift (stock SC powered seats are about 74 lbs without the heat option if I recall correctly). For me this would not work since my neighbor's car parks fairly close to mine and the driver's side door is therefore only able to open 3/4 of full extension. There just wasn't enough room to remove it without risking a scratch to the paint on either car. Also it has been a few years since I removed SC seats but I think the door needs to be fully extended for clearance anyway.

Nonetheless, I agree that temporarily removing the driver's side seat would help if it is possible for the DIY'er.


If you do want to try seeking out a new one definitely shop around at dealers that offer online discounts. I ended up paying $350 shipped from within the USA. Not cheap... but I saw significantly higher prices listed elsewhere for new stock. Otherwise there is nothing to lose by going used.

Glad it may help you in the future, Duck05. Not much has been documented about this and I'll be happy if this post helps anyone.

....

Removing the instrument cluster is an interesting idea and I did think of this but it is still cramped in there. It could be tried but I don't recall what lies directly underneath the cluster that may block the Mirror ECU upper mount.

I have taken my entire dash out before (if I'd known this would have been an issue when I did I'd have removed that 10mm bolt at that time) and that alone is a tedious amount of work and organizing of pieces, screws and nuts. That would probably be the way to make this bolt easy to access... but at the cost of a tremendous amount of work.

Removing the radio/HVAC units and removing the rear center arm rest and console are definitely required to give yourself ample clearance to do this the way I described and that approach was described by someone on the us.lexusownersclub.com forums (I think I've typed the url correctly).

The 10mm screws both face toward the cabin at a perfect horizontal angle. It's actually possible to see how a simple 10mm closed-end wrench with an internal ratchet of sufficient length could be put onto the bolt and wiggled back and forth to eke the screw out of place gradually... however there is another module that has something to do with the HVAC system (I think?) directly in your way preventing you from being able to do this. It is a black plastic box with what looks like two small rubber hoses coming off it (or else they are two heavily insulated electrical wires).

I also considered getting that black plastic box removed to clear room to access the Mirror ECU bolt but this also looked like it would have been an involved process. I never tried it because it didn't look like a very good option. I could be totally wrong but that is my opinion.

Accessing from the radio area sans center console trim with a socket extension and angle/swivel seems to me like the best approach even despite the frustrating aspect of aligning everything and keeping a very tight lock on that bolt.

More removal of the dash could be done but I really don't think it is necessary. Pulling out the cluster is the one alternative I am curious about but I can see that when doing this one would also need to disable the airbag and remove it along with the steering wheel.

Note: ALWAYS wait a minimum of 2-3 minutes or better yet 3-6min after you have disconnected the battery before disconnecting any of your airbags. Always reconnect your airbag and cluster BEFORE reconnecting the battery or you will have an airbag fault CEL code which will not go away until you clear it with a specific procedure.

I also thought of using a 10mm socket that has a magnetic end. That certainly would have helped once the socket made positive and secure contact with the 10mm screw. I can also see how the magnetic socket end could get caught up on many metal surfaces it has to pass by just to get to the 10mm screw, requiring a lot of prodding to keep it on the intended path. So that idea might or might not be of more help.

It is really not so crazy a pathway for the socket extension (I used a 12" extension) and the swivel connected to a stubby 10mm socket but it is tedious to get it there correctly and keep it there.

I wish I could confirm anything that would make this chore easier to do. As it is, this DIY approach is difficult but still was less work and time overall than removing the entire dash.

Returd

nice write up, subscribed so I can find it. My mirrors currently work on my driver car, but I'll be sure to test and salvage these parts from my parts car.

salimshah

I was tempted to remove the instrument cluster to see if that allowed better access.

As suggested, the replacement is not secured at the top.

Salim

drseth

Hi, I am faced with the same issue with the ecu. I have another ecu to replace the one that is not working. The small connector came out easily, but the large connector doesn't want to loosen. I appears that another wiring harness is blocking it. Very tight wiring there. Do I need to disconnect that blocking harness to access the large connector? Is there a trick to getting the large connector off? I got the passenger window fixed (broken wire in driver door hinge), but wonder if maybe a broken wire is what is causing the side mirrors not to be working.

I tried jumping a hot wire to the different wires that attach to the mirror switch to see if anything would work, and nothing happened. Did same with ground, nothing. No continuity to any wire going to the switch, neither hot nor ground. I haven't been able to find a wiring diagram.

With 3 fused vertebrae in my neck, and carpal tunnel syndrome in both wrists, I don't have the physical ability to do much, but I like to try.

KahnBB6

iTrader: (5)

The two connectors on the Mirror Control ECU should have locking catch tabs that can be undone with a small flat-head screwdriver. The physical plugs may be in there a bit tight but they should come out with some wiggling. Just mind the wire ends.

What happens with the side mirrors is really that the ECU fails at some point. It's more than likely that rather than a short in the door if everything else is working. For me the Mirror ECU failed at 235k-ish and 24 years. Pretty lifespan. Your known working ECU should be a good bet unless you want to buy a brand new one. I still have my old Mirror ECU that I want to have looked at by an expert to see if they can be serviced or if the electronics inside that control memory function can be bypassed (I have NO idea if that is possible right now).

Replacement of the ECU is currently the known fix for this issue if BOTH your mirrors have stopped responding.

Okay, this may make you an exceptional case. I actually do not recommend you try this fix yourself if it means you will have trouble your preexisting back condition. Also, I tried this repair without having removed the driver's seat. I think in retrospect it makes much better and safer sense to remove the seat in order to gain better access to the footwell. That will possibly cause you some less strain on your back and neck but it may not be enough in your case with fused vertebrae in your neck.

Also, to anyone reading this I highly recommend a set of safety glasses or goggles that will not fog over. You should expect a fair amount of random dust and interior debris to fall onto your face while doing this job.

Being totally frank and erring on the side of caution and your personal health and safety, I think you should not attempt this fix yourself in your condition. Maybe I am overthinking this but my feeling is that you, drseth, should not risk it since it does require your head to be right up against the footwell and you may encounter some straining for the more difficult task.... which will be to remove that awful upper bolt.

And believe me, the way I have described doing it is about the most efficient (however annoying) way I could think of to do this other than removing a large amount of the dash and dropping the steering column. Some wiring in the way of access to that upper bolt looks like it could be removed to make things easier-- and I did try that-- but it really was counter-productive to accessing it through the open radio area via a series of socket extensions, bendable socket angles, a lot of trail and error getting that socket aligned onto the bolt and pressing on it VERY HARD while working the socket once it made 100% firm contact with the bolt head's base. Getting the socket arrangement aligned in there correctly and actually getting positive contact of the socket and bolt is the truly difficult part that one just has to have a lot of patience for due to how easy it is to get wrong... until you finally get it right. Unless you're very lucky early on.

It really is a terribly placed bolt for what would otherwise not a difficult ECU to replace. Once that bolt is removed I DO NOT recommend trying to replace it. The other mounting, bolt points and two connector wires this ECU has are more than enough to hold it in firmly without that far upper bolt being in place.

drseth, if it is possible for you to get some help to do this I would recommend it. I'm sorry to say that but the condition with your neck concerns me when it comes to this DIY.

Returd

I have my interior out, and am just about to reinstall. I'm thinking I'll take a look for this dastardly bolt and take a shot at removing it to make life easier should I ever have to replace the mirror ECU.

I happen to have this switch/relay/computer diagram and assume the mirror ECU is one of them?

tsmith1315

By all means, get it out now! Looks like 89230 on your diagram is it. It lies just to the left of the center air vents. I would also be curious to know if removing the instrument cluster would be helpful. I spent a dozen years or so installing car stereo, so laying in the floor working overhead is no big deal to me. But the sheer amount of stuff it's necessary to remove to get to one stinkin bolt made me wonder if I was actually working on a British car. Here's another diagram:



-Tim

KahnBB6

iTrader: (5)

That original Toyota microfiche diagram is accurate in a rudimentary way. The Mirror ECU should be the one pictured magically floating over the steering column but which is actually nestled underneath and to the side of the steering column assembly. It is very accessible from the footwell-- OTHER than the hellish upper bolt.

If you are planning to remove your dashboard anyway then yes you should have a much easier time getting to that one bolt. Taking that one upper bolt out and leaving everything else as is will make future replacement of the ECU much easier and possible to complete within minutes.

Aside, there is no beneficial reason to replacing the actual Mirror Control ECU box unless a failure has been confirmed. That upper bolt... yes.

Yes, it looks like 89230 in the other diagram in the previous post. In this diagram that tsmith has posted Toyota makes it look like it is placed in a higher position than it actually is. It actually is placed closer to where this diagram shows the Cruise Control ECU although it is not in the same location as that one is (which I am sure is not 100% visually accurate in the picture either).

The Mirror ECU box is above the footwell pedals, mounted at an angle. It is held in by: one lower bolt (easy), two harness wire connectors (easy), a tension tab A on one of its mounting arms fitting into a "slot B" receptacle (easy) and the one far upper bolt (utter sadistic cruelty).

The visual representation in the diagram in Returd's post is more accurate.

Also, here's my old one:







The way to see the Mirror Control ECU is to get yourself into the footwell, head up (I do recommend fog-free goggles to avoid getting random dust and debris in your eyes) and using an LED flashlight that can rest on your chest. Or maybe an LED headband lamp.

With the dashboard out (a big job. I've done that one before) you should have no problem getting to the pesky bolt and removing it. Just make sure you can trace the correct bolt to the actual Mirror ECU before removing it.

Returd

I didn't get a chance to attack the hard to reach bolt before re-assembling my car. I was working till midnight the night before I left just to get the interior back in.

I can say i had a quick look and removal of the center console did not make access any easier, as in I couldn't see or get to the ECU any easier. If the HVAC duct work were removed maybe, but that would probably mean removal of the majority of the dash.

Short story, i think your description of how to get at that poorly placed bolt is the way to go.

joe diego

iTrader: (3)