sshhlexus

Glad to so see Mr. Yamae's commets, being posted today.

93 LS3400 is running fine 99% Okay, ... my history of dealing with this is posted on this thread and one other related thread on this site.

When the symptoms first happened I had no idea and never saw an ECU. I studied some electric circuit theory decades ago and even built some simple audio devices using "perf" boards decades ago. So before spending really big money I was LUCKY to find this site with this thread.

If Mr Yamae reading this, can you please shed any information on:
- 3 very small connections clipped at R584 on the original board, all capacitor upgrade work done 100% according to the info from this very thread

What would be the consequences of the clipped connections? So far the only thing I'm experiencing is:
high idle on P and N when cold or warm
tachometer always reads zero

Since the tachometer is not working, then to my ears on P and N sounds like 750-850 rpm. On D (idle) sounds normal, much lower rpm.

All else is 100%

Thanks in advance

LScowboyLS

are you talking about the ECU that had the silly wire on the back of it?

sshhlexus

Yup. That's the one. I removed the wires and did my best to inspect the board awhile ago and found 3 small traces clipped. Right now I'm thinking of the old adage "if it ain't broke don't fix it" approach. I never leave a car in P or N for any time.

I'm keeping my eye on the MPG, last fill I computed 18 MPG (mostly city).

Yamae

Let me confirm what you wrote about 3 very small connections clipped at R584. Will you explain me a bit more using the photo attached below?

Do you mean "clipped" as "not connected" / "off from the board"?
English is not my mother tongue and I often have problems not understanding things precisely.

LScowboyLS

none of the traces on the board are optional if you want the car to operate completely correctly!

however it does take a very very skilled technician to replace traces on a circuit board, there are not a lot of technicians in USA that can do this delicate micro-surgery!

it would help if you could post a really high resolution photo of the affected area

sshhlexus

You Lexus guys are absolutely amazing. Mr. Yamae's photo was right on. I've edited the photo with MS/Paint to hi-lite where the traces are. Hope the pictures looks okay.

The 3 small red arrows indicate where the traces are clipped, cut or severed with a sharp blade such as a pen knife. The cuts are less than 1 mm thickness. No other components have been removed from the board in my observation.

I understand your English just fine Mr. Yamae. I speak 3 languages.

Thanks in advance.

LScowboyLS

the traces just need to be repaired, unfortunately, finding someone to do that who is competent is going to be tricky outside of a few areas such as silicon valley, CA, Huntsville, AL, etc. - has to be somewhere where there are a lot of electronics design and manufacturing companies.

You need to see an example of someone's work before having this done, this is *not* something your "local electronics shop" guy can do, nor can any car-related company, unless you have a friend who works for an actual auto manufacturer's electronics division.

sshhlexus

Only the surface traces were cut, where shown on the edited picture. The cut did not go deep, just enough to sever the connection. The gap of the cut is about .5 mm.

My idea before was to use small pieces of wire braids from braided wire. Small enough pieces to cover the junction, approx. 1 - 2 mm in length. I kind of stopped there in my analysis. Then I remembered electrical conducting glue, not sure about it, if such a thing exists. I read that it is no good. Especially for this kind of microscopic repair. So I stopped there with this particular ECU.

I want to try the 2nd replacement board I now have, I've been too busy recently with a bunch of other things. I don't have a lot of car area space around my home and it is one thing that I regret.

Update: This morning on its own the tachometer decides to work, after about a month of just reading zero. Drive idle is a consistent 600 rpm. P/N idle read 1050 rpm even after approx. 15 mi. city trip. I'll check again later as the outside temp warms more. The tach malfunction is obviously also related to the cluster circuitry.

Thanks Cowboy.

SuthernLS

Having some issues with stuttering, fuel economy with my new (to me) 96 ls400 and googled up this info. Great stuff but still building up my confidence and think I need to buy a soldering gun kit and learn how to use it.

LScowboyLS

here is the best soldering gun that is a reasonable price

Yamae

The heat conductivity of the board is so good that you would have a bit hard time trying to remove old capacitors if used an old type soldering iron which doesn't have a temperature control. You'd better to use a soldering iron which can control the temperature and set it max 400 degrees C or above when removing.

When I do the removing job, I use a soldering iron Hakko MACH-I 918 which consumes peaking more than 150W but it is rated 55W. This one is 24 years old but still works great. There were 3 types of them ranging from 300, 370 to 420 degrees C. I have all of them and I make it a rule to use 420 degrees one for the capacitor job and I use 370 degrees one for the new capacitors to solder.

Hakko MACH-I 918 series were discontinued but newer series like recommended one by Cowboy is capable to adjust the temperature and you don't need to buy many irons like me.

LScowboyLS

I use around 396° C for all parts of the job

Tuha

Hi All.
I cannot sing enough praises for this forum. I am busy with building/restoring my 95 Celsior and enjoying every bit of the process so far.

I'm ready to order capacitors and just want to confirm the quantities. It is recommended in this thread that we go:

1995-97 LS400 needs 6 caps as follows:

Qty. 2 of 10uF - 50v
Qty. 1 of 47uF - 63v
Qty. 2 of 100uF - 10v
Qty. 1 of 220uF - 25v

My ECU, unfortunately, is one of the series 89661-50241 which are notorious for issues such as random stalling etc. I can't afford to replace this ECU as suggested by Mr. (sign of great respect) Yamae so I am going to do my best with what I can.

This is where it gets a bit weird. I counted 9 caps in my ECU as follows:

2x 10uF - 50V
2x 15uF - 35V
2x 47uF - 63V
1x 220uF - 16V
2x 100uF - 10V

Can I go ahead and replace the 15uF - 35V also with 10uF - 50V or should I just stick as close as possible to this capacitance and voltage while making sure the caps are low ESR rated to 105C and from one of the brands stated here?

I'm sorry if this question has been answered already in this or other threads. Let me know and I will continue searching. I'm at work and did not have time to research properly.

You can check out my build for (crappy) photos etc. https://www.clublexus.com/forums/bui...-from-nam.html

RupertD

Tuha hi , I found my 96 RHD UK model also has nine capacitors .
I used the 15uF - the 63V Chemi-con KZE EKZE630ELL150ME11D as recommended by LScowboy and Yamae at the start of the thread , don't use a 10uf it is ok to use a higher voltage but not a different capacitance .
Changing these capacitors is well worth it ,I have now done all three of my cars . The biggest change was on the 94 feels like a totally different car ,have not tested the 96's much yet but they do feel more responsive .
Good luck with yours.

Tuha

Thanks Rupert. I will do just that. I can't wait to check out the results.
Happy Easter