Yamae

Congratulations on you success! Another happy owner!

Didn't you have any chance to check the ripples at the diag connector as my post #232 before you have replaced capacitors? This could had helped you to judge the bad capacitors.

LScowboyLS

more amazing results!

just applied this fix to two vehicles, a 1986 Nissan 300ZX with intermittent cutting out and power loss while driving, and a 1996 Acura RL with starting issues and occasional power cutting out.

both cars now drive like new!

nicosky

Can I try this recapping thing with my Lexus IS200 (LHD)? I have an on and off issue with my ECTS (Throttle system). I placed my ECU box with foam insulator and the engine limp mode just stop. I suspect that ECU get maflunction when its hot.

Another thing, since the Lexus IS 200 ECU box is located front side of the engine. do heat temp shortened the life of the capacitors? I didnt notice any leaking capacitor on the ECU even a burning smell or something. 9 of its capacitor are matsu****a (M) (panasonic). can I replace them with rubycon or nichicon?

Yamae

It's not easy to tell with that much of information to me. Heat related problems are not only caused by capacitors.

Of course it would be a good idea to replace electrolytic capacitors using those recommended ones as a preventive measure. But I don't know your heat related problem is fixed or not just replacing capacitors. According to my experience, heat related problems are mostly caused by semiconductors or cracked soldering points.

Pick up some of those capacitors and measure the capacitance and the ESR. If they are too away from the range, your problem may be related to capacitors.

nicosky

Thanks.I'll let you know if Im successful recapping my ecu.

LScowboyLS

Matsushi-ta (Panasonic) tends to make extremely reliable capacitors, every bit as premium and reliable as Nichicon or Rubycon or Chemicon - there are no known Panasonic capacitors with factory defects involving leakage etc.

However ALL capacitors deteriorate with total age as well as power-on time, especially in the higher heat of an engine compartment as opposed to our LS400 where the ECU is inside the passenger compartment.

An even more likely fix is adding some Arctic Silver 5 thermal conductivity paste to the power transistors and voltage regulators, and CPU's where they adhere to their heatsinks or to the ECU case if that is aluminum and used as the heatsink, as it is in the LS400 and most Japanese ECU's. Clean off any old paste with alcohol before applying the new.

Also, you may find that one or more of the fasteners used to secure the power transistors/voltage regulators/CPU's to the case is not absolutely tight, and when you apply the thermal paste linked to above (no substitutes) make sure you use an extremely thin coat, just enough to cover it, about the thickness of a sheet of rice paper!

As yamae and I continue to stress in this thread, it is not only the manufacturer of capacitor that is important in replacement, but also it must be this manufacturer's low-ESR series of caps.

brianmch

Okay, so I'm a loser

I dissambled my dash/etc to get the ECU in, well, January. Long story.

Now I've got the caps replaced (ordered from Digikey, re-placed by a computer shop that solders motherboards, so I figure they know what they're doing).

All the boxes are screwed back into position and I thought I had all the connections correct. But of course not. Won't start, beeps, and the ABS light stays on. I've unplugged and re-plugged the connectors but to no avail. Installed new battery as well as the other one went kaput.

I followed the thread closely at the onset and didn't see detailed pics of the uninstall/reinstall process to see what flippin connector I may have crossed.

Any ideas?

Brian

LScowboyLS

well I hope you didn't disassemble the dash - all that is required is just to remove the lower glove compartment as shown in the diagram in post #1

I am also not understanding how the connections could be wrong, as each connector is unique.

you can call me, will PM my number to you

Candysking

My previous post in the 96LS misfire thread: " also have a 96 LS with 224,000 miles, have owned it since 30K. Was running exceptionally well up to 2 weeks ago, when it began misfiring, intermittently. When I would shut it down, then start and run again, would operate fine for 1 - 3 days, then suddenly would exhibit the same problem. Seems, when I would reset the check engine light, by disconnecting the battery, the car would run fine for awhile. Took it in, error code showed misfire # 6. We changed plugs, wires, rotors, checked compression, (180). I am still getting the same problem, only more and more frequent. Hoping you can advise your final fix.."

Misfire problems got worse the past several weeks, and had to pull her off the road.

Got keyed in to this thread, finally removed my ecu last weekend, and of course found at least one leaking capacitor. Ordered a couple sets from DigiKey, per LS Cowboy's ideal specs in initial post. Will have caps in hand tomorrow, and am taking the unit to my neighborhood Electronics repair shop. Not something I trust myself with. Hope I can report back all my problems solved. After driving my LS for 200K, can't bear to call it quits. Look forward to many more. Thank you LS Cowboy and Yamae for hopefully getting baby back.

LScowboyLS

just make sure they use the caps I linked to in post #1, no substitutions, and make sure all of them are oriented correctly (polarity wise +/-) and that the correct value cap is in the correct place - take extensive photos after they are done of their work and we can tell you if they did it right!

diamondave

I changed My ECU Capacitors and it made a big difference! Runs a lot smoother and it has a lot more power. Thumbs up LS!!

BobSmith00

Well Let me run down a few things, and see if anyone agrees the ECU Leaking Capacitors could be to blame...
1) Sometimes the speedometer hangs out at zero when starting car, a brief but brisk tapping action would make it come to life, other times it came up on its own. Not sure if I've ever noticed it with the tachometer.
2) At times when first starting car, would go into Reverse and move back as expected, but any forward gear would just not go, and just hang out for a few brief to longer moments before going.
3) Headlights Dimming sometimes at night, a bit of a flicker to them.
4) Battery not charging, but alternator testing good at partshouse.
5) Fuel not getting from the tank to the engine, car starts but dies instantly due to no fuel.

Sorta not really sure whats going on with the car at the moment, I'll make a post and hopefully get some quality feedback, or at least a ball park idea. Not too many folks know much about Lexus cars in my area of Mississippi.

LScowboyLS

1, 2, and 5 could definitely be due to failing ECU capacitors

3 & 4 are likely related to each other and probably not related to the ECU

so my guess is that you likely have multiple issues

on 3 & 4, I would be looking long and hard at all of my large under hood fuses, battery connections, especially the + terminal end piece that unbolts and often goes bad from hidden corrosion, p/n 90982-05037 - $15 at any Toyota dealer, and well as verify all engine to body grounds, such as the two on the back of the engine as well as the one at the A/C compressor.

also verify all fuse links, circuit breakers and relays, and just do a good physical inspection with a headlight at night, so you kind of scan the engine bay with a narrow beam, and often times you will scan across a wire with your head lamp and say "what the heck, this should not be severed!"

I would strongly suggest picking up the real Lexus LS400 factory wiring diagram, about $30 - $40 on ebay, give me the year of your car and I will send you a link to the right one.

issue #5 could also be related to 3 & 4, by the way, such as a power circuit that feeds both the alternator and the fuel pump relay, for example.

BobSmith00

Thanks for the response.
Issue 1,2,3 don't really cause me any grief as long as they do not get worse, but I do know at some point I am going to have to do the cap replacement. But I've already sourced someone to do it, that is a bit more skilled than I at such things.

I was mostly hoping that tossing in those first few issues would help shed some light on things.

Here is a little more on whats going on. I drove to town about 14 miles a couple weekends ago, car did fine.. Went to start the car up after shopping, car seemed to be only at like half power, then I noticed the AC wasn't blowing all that hard, and then dash lights were dimming before going dark, and the car died. I hit the battery with a multimeter and saw it was way low. Let it sit a bit, it got back up to 12.58 V, and car started up just fine. But a check of the battery with the meter saw the battery steadily going down. Until it reached a voltage too low to operate the car. Got it back to the house, took off the alternator since well that is what I thought was the issue. Had it checked twice, both times it said it passed.

Put that alternator back on, tried a different battery. Car was strong and seemed to be doing fine. But after driving a bit it started losing power, but I had a spare battery with me so I got back home.
Talked to a wise older fella that said it likely was still the alternator, so I picked up a rebuilt alternator. Went to get the car up on the ramps to do the work. And as I was lining up the car with the ramps, it went dead. I thought at first it was just the battery was getting drained so I let it sit a bit, and tried again. It starts but dies instantly, I suspect because it is not getting any gas. That was yesterday, it was storming a good bit of the day today so I didn't get to mess with it, but I tried to source information

No sort of catastrophic thing happened that I'm aware, I drove the car about 200 Miles, then it set for a couple days, I drove it about 14 miles and that is when it went dead the first time. Oil got changed a few days before I drove it the 200ish miles. Filled up the tank on my travels, and I still have 3/4ths of a tank, but as best I can tell none is getting to where it needs to be. Am thinking about taking off the fuel filter to see if the pump actually does anything when turning the key. I'm suspecting not, and that it is likely some fuse(s)/relay(s) that has went amiss.

Its a 1996 LS400. I've barely put 15000 miles on it, but its so far the best car I've had. Minus this whole issue.

Thanks much Mr Cowboy.

LScowboyLS

make darn sure they are very highly skilled at soldering, and make sure you supply the exact caps I specified in the links in my main ECU article - these caps are a very special type, and I have yet to ever open up an ECU who had the work done by a professional place who actually used the correct caps and did a good job, so beware!

Start with a brand NEW battery that has been fully charged on a charger after you get it home and the distilled water level checked, you don't need that variable messing up the process

put a voltmeter across the battery the next time you successfully have it running, and see if you have >13.5V at idle to verify you are charging

There are a couple of large fuses and also a fuse link that can prevent a good alternator from charging, check those, I don't have the service manual in front of me or I could tell you precisely which ones (I am on the phone, not at home), perhaps yamae can chime in


the not getting gas could easily be a fuse, fuel pump relay, or fuel pump mini-ECU or even ECU caps or something else entirely, perhaps not even fuel, I would check fuel pressure at the rail or at least pull a plug and see if it is wet