94V8coupe

How prone are these units to failure?
With respect to power windows ...
Driver door window always works.
Other three are intermittent (when using driver door master switch).
Other three windows always work using their own respective door switches.
I pulled the master switch and tested window switch continuity for all operations and it tests good (at the pins).
Next place to look I would think is one of the ECU's or the wire harness itself.
Has anyone else run into this issue?
Car is a '95 incidentally.

Yamae

The body computer is weak against the too much current.

As far as I have experienced, I have seen several body computers failed due to customer's mistakes. Some caused by LED lights or some trying to add extra loads. Short-circuiting the current output line or too big current loads often damage the body computer before the fuse opens. This stresses the voltage regulator inside and the body computer's function becomes unstable. The quickest way to troubleshoot is to replace the body computer. Some skilled guys would fix it though. Actually I have fixed some of them.

94V8coupe

I doubt this is the case here. "Adult" owned and not messed with in such ways.
In your experience ... which would be the most likely be the failed unit? Door or body computer?
Thanks.

Yamae

If the body computer is not messed up, the possibility is 50% and 50%. I would monitor the signal line between 2 computers.

94V8coupe

Not quite sure how I would go about that but thanks

RelentLex

I just fixed this exact issue on my 95. Its your driver door "MPX Module" (master window module). You can find one on ebay, or junk yard. Very easy replacement took me maybe 20-30minutes.
Good luck

94V8coupe

Excellent. Was not looking forward to extracting the main BCM. A door panel I can deal with. Still a pain but nothing I have not done before

RelentLex

Yeah, once you finish this repair though youll think "that was pretty easy"...I was expecting this to be some big issue too when my windows became intermittent.

Once you remove the door panel this module is located at the top right corner of the door (looking straight at it) - basically under the driver door mirror. Youll see it.

Also these funny module issues seemed to be most common on 95's (including ecu)....it was first year production of 2nd gen. Later models had seemingly far less of these gremlins.

Do you know what ecu# you have? does your car jerk when you let of the throttle at highway speeds / above 80km/hr ish?

94V8coupe

Good to know. Another little "gremlin" I have noticed is the steering wheel not always fully pulling away when the key is removed and not fully returning to the last position when the key is put in. And it's not the motors. Motors are fine. I know this can be a problem. It's electrical for sure. Another intermittent situation. Sometimes it works, sometimes not. Mostly not. I would just set it where I want it and shut it off but on these you can't. On the earlier cars you could. I understand the steering wheel (power tilt & telescope) has it's own ECU as well. hmmm...



So I am learning.

Funny you should ask. I certainly did have that problem until changing out my ECU a few weeks ago (now that was a pain - lots of stuff has to come out). The "off throttle shock" situation as Lexus coined the term is completely gone. Shift quality is over-all better and there is more power and better throttle response across the board.

What remains is this B.S. "low idle" situation which comes with a side of vibration / rumble/ shudder. This is the symptom that put the whole ECU thing on my radar.
I was lucky enough to find one with the updated part # (I will add that later) that came out of another '95 that got scrapped.

I will update this later on with the original part # (the one I took out).

RelentLex

I have seen people setting the steering wheel location they like then removing power to the motor. Id do this too if mine didnt work properly maybe but mine still works without issue.

Ok yes, your replacement ECU# was one thats been updated, though if yours came out of a scrapped car with an ecu thats never been rebuilt it could still be the ECU. though seems like you had a bunch of improvements with the new ecu so perhaps its working fine.

The low idle could be many different reasons. Mine used to be low only intermittently, not always. I dont believe when I had my updated ecu (#50225) rebuilt and put in that it made the low idle go away.
I deleted the idle up valve in the power steering on my car a long time ago (not due to low idle, but because the valve was leaking and I wanted to try the delete to see if i like it or not), and I think that made the idle better. Though I havent driven my 95 much in the past year+ so I dont remember the current state of my idle, but it was mostly always at 650. I believe. Some peoples cars are idling low at all times.

94V8coupe

I have heard of that but to be honest I really like that feature so me being me ... I will try to make it right. Like I said though, the good thing is, the actual motors are fine. I can't stand having anything in my car that does not work. Which is why I had the whole center stack out last weekend swapping in a new climate control and faceplate (with working LCD) on my radio
Kind of what I was thinking but I take nothing for granted. It is a #50224. You got the absolute "latest" part number they ever put out there eh? Where did you find that diamond in the rough? I have had them both open (original and replacement), no caps are leaking ... doesn't mean they are good though. Maybe that's the one thing that effects idle speed the most? I dunno. I mean, if it throws things off to the point where the computer is sending out bad reference voltages to sensors ... that could be a problem. Considering doing the re-cap.
This is interesting
Funny thing is, mine will idle at 650, but even at that speed it will still (more often than not) have this annoying resonant rumble / vibration thing going on that comes across like someone pumping out a continuous low frequency through a subwoofer. Very unpleasant But it will inevitably dip lower. And lower. 400 is about as low as it gets. For now.

RelentLex

Just randomly got lucky on ebay. Was looking for a 50224 and saw a 50225, didnt even know that existed. Search it up and found out the same thing, that it was the latest ECU# made for 95's. So i scooped it up!

94V8coupe

Got it done. Problem solved ... thanks for the info! Worst part of the job was two of those "posts" that the red push in clips are on pulled clean off the door panel. Old glue just gave out. It will be fixed before the panel goes back on.


"new" part

Door skin removed

suspect part

new part installed