LScowboyLS

The A/C problem you have is definitely not ECU capacitors, it sounds like a vacuum leak, disconnected cable, A/C control board (capacitors) or door motor, for a few possibilities

I would go to the Toyota tech info site, get a 2 day membership for $15, and download all of the A/C troubleshooting pages of the factory service manual - I would probably download the whole chapter on A/C, especially the parts about diagnostic code reading and the sections on the various doors that route the airflow, and troubleshooting flow charts etc. - unfortunately you have to download a page at a time, but at least you have at least 48 hours to grab all you can! - cheaper than buying the entire factory service manual! - just find your year and you are ready to go!

Yes there is an entire thread (more than one) on instrument cluster capacitors - it is one of the most viewed of all time

kene

iTrader: (2)

I just replaced the capacitors on my 94 gs300 ECU. The factory capacitors all looked perfectly fine on the outside, but I suspect that they were causing some issues.

There were 9 capacitors in total (listed below). The soldering was a bit hard at first duen to using a 30 watt, cheapo soldering iron. I plan to install the ecu in the morning and I hope everything goes great the first try

2- 10uf
2-15uf
2-100uf
2-47uf
1-220uf

I also bought an excessive amount of capacitors and I have every size listed by the OP in my possession. I would be more than happy to help fellow members that may have a hard time sourcing them. Just pay for shipping that's all.


Great post.

kene

iTrader: (2)

I'm impressed to say the least. I was a bit afraid, and second guessing my solder work, but when I reconnected the battery and turned the key everything ran up fine (Still takes about 1-2 tries at cranking, and then a 2-3 minute warm up before idle is fine. But I attribute this to the coolant temp sensor code and the knock sensor code).

All gear shifts are much smoother than before, and the throttle response seems much more precise. I even had the transmission fluid flushed out on 2 separate occasions with OEM fluid in the last 2 years, and it made a slight difference but not like this.(when gas pedal was slammed to the floor, tranny shifts would "kick/jerk" when engaging next gear)

Now granted, I just did one test run (~110mph) so I will see how everything else goes from here on out.


From a fellow EE,
Thank you LScowboyLS & Yamae for this.

TNice94

New here to the site..I'm thankful of all the help just from reading these threads. I've owned my 94 ls400 a little over three weeks now. As of the first week seing lots of the symptoms listed in thread. Brought in to Dealership last week with hopes they can confirm my ecu problems.. And they did.. check engine light was not on when dropped off, but while there Diagnostic of issues I stated. Light came on then. Technicians words( Attempted to communicate with ECU and found Internal Failure in Engine ECU) .Estimated cost to replace Main Engine ECU $1300. NOW I'm attempting to remove ECU.. Ive got the glove box out and see the two 10mm bolts but am stuck here. Today is Saturday so will be attempting again. Will give update.

LScowboyLS

there is a diagram in post #1 of this thread for a 95-97 model, the procedure for a 94 is similar

you need to remove the lower glove box, seems like there are 5-7 fasteners total, I don't remember the exact count, but one them is often hidden in a secret panel inside the lower glove box - it took me a while to find that one the first time!

just take your time and don't force anything, once all of the fasteners are out, the lower glove box will come right out

then you need to locate the ECU, it is a box approx 9" x 6.5" x 2" and it has 4 large electrical connectors going to it with between 90-100 wires total between the four connectors. No other box up under there has this many wires going to it. Also it will have a 10 digit part number in large print on one side, the first 5 digits being 89661

there is often a couple of bolts up high under there (near the top of the dash) that you may need a long 12" extension to reach, and the CD changer may have to be removed or at least loosened to get access

I am maybe making it sound harder than it really is, I would recommend putting a pillow in the floor board since you are working upside down, and I like to wear a head lamp so that I have both hands free!

once you find the ECU, disconnect the negative battery cable before unlocking and disconnecting the 4 big connectors with their squeeze tabs.

It is a good idea to wear cotton clothing and bare feet when handling an ECU for static electricity protect, especially in the arid west or in winter!

Good Luck, and once you have done it once, you will consider it easy the next time!

TNice94

Alright I've got it!! That's not as bad as I thought. Now the fun part . Opening up the ECU. https://www.clublexus.com/forums/ima...ilies/woot.gif

LScowboyLS

I would do a lot of practicing on old computer motherboards first unless you are very experienced at soldering and replacing capacitors - it is not easy for a first-timer!

and please do not deviate from the exact brand and model number and ordering source for the replacement capacitors that I have linked to in post #1 - all of the capacitor makes and models that will work correctly are listed there and linked, and don't buy them on ebay or anywhere else or you will likely end up with counterfeits! - the particular capacitors required are a very rare type, and just barely available outside of Japan, you cannot buy them locally (unless you live in Silicon Valley)

sshhlexus

Also, one should read up on what to do when you hook it back up. I hook the (-) battery connection last. Then I let the ignition position before start to run a bit, I hear from what sounds like a fuel pump, it stops after about 5 - 10 seconds, wait a few more seconds, then I turn the car on.

Drive the car in stop and go traffic for the first 10 - 30 miles. This is to help the ECU reprogram itself with new caps and with being disconnected/reconnected.

LScowboyLS

good advice

TNice94

hhmmm a little stuck here.. After removing the screws from the outer case then screws from board itself. I fold open to view inside(being careful gentle with ribbons). It looks like there is five more screws inside on the wall .. My Question is do I remove the 2 board the ones with capacitors? Or do I leave it in the case? And I'm only doing this to inspect.I will not be doing the repair myself..

TNice94

I do live in silicon valley. Is there someone out here were I can purchase? and is there someone you can recommend to do rebuild in this area?

LScowboyLS

the easiest and cheapest way to get the best deal and fast, and be certain that you do not have counterfeit capacitors is to use the handy links I have provided in post #1

although I have seen the work of perhaps 30 or 40 different rebuilders, I have never seen one who both used the correct rare capacitors, got them in the correct locations, and did a good soldering job on the repair - this is why I figured that teaching people to do it themselves couldn't possibly turn out worse than the Beavis's who are currently doing this work.................ugh!

PS - avoid anyone you see offering ECU rebuild work on ebay, craigslist, or this company drift motion to name three places in particular. who really massacre this job, although there are dozens of others out there who screw it up as well, not sure if they are just cheap, in a hurry, or just don't know any better

sshhlexus

As long as you've exposed the board with the caps, there is no need to further remove screws that attach pin blocks, side brackets or sides of the box.

TNice94

I will order from the links provided. Thanks again...

mahans7

Just installed my ECM with new capacitors on a 1994 ES300. Wow, what a difference especially with shifting and idling. Had a lot of trouble getting the capacitors out and finally bought a Hakko 808 desoldering kit with a 1 mm tip (in addition to a Hakko 8888D soldering kit) and it still wasn't easy but I finished removing the capacitors in a couple of hours. Soldering in the 6 capacitors took about 5 minutes and I did use the recommended capacitors obtained from Digikey in duplicate for $8.64(unbelievably inexpensive).
Capacitors: 220 uf 10v, 110 uf 10v(X2), 47 uf 63v and 10uf 50v.
Thank you LScowboy and Yamae and other posters, I couldn't have done it without your help. Wife, as of today, loves the car.