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This pic shows where the cap (c104) leaked and burnt off. I was wondering if this ECU can be fixed or if this board is no good. To me it looks no good but I've never worked on any of these so I need some advice. No sense wasting time and money sending it out if it's no good.
I would bet it is toast. My '93 had C104 still intact and no other caps had leaked but when I removed it there was evidence of electrolyte in the plated thru holes and on the other side of the board. I couldn't fix mine. If you send it to a rebuild shop and the board is bad they will try to sell you one that does work. The replacement parts are cheap from DigiKey but the rework is tedious so unless you are good at board work it isn't worth it in my opinion.
I would bet it is toast. If you send it to a rebuild shop and the board is bad they will try to sell you one that does work.
The replacement parts are cheap from DigiKey but the rework is tedious so unless you are good at board work it isn't worth it in my opinion.
That's why I put the pic here, so someone with more knowledge then me can see it and maybe save me the time and money. I don't want to send it in and they say "Well, we can't fix it but we still charge you the labor to check it out. And also we can sell you one of our re-manufactured units for triple the price you were gonna pay to begin with."
I was looking at the prices for the caps, which are cheap, but I would also need to buy solder, a gun, flux, and whatever else, so it's better to send it out. Plus, there's no way I can see good enough no matter how much magnifying I do. If I was able to go without my car for 2-3 weeks I would just send in the original from my 94. So now I check the junkyards. Thanks.
You are absolutely right about the equipment needed to do a good job. Probably the most important as you mentioned is good magnification and generally that doesn't come cheap. Whenever I work developing cell phones it is essential to have a good binocular microscope because the discrete parts are so small they obey electrostatic forces instead of gravitational forces. For instance surface mount capacitors such as 0201 caps are about 0.2 millimeters long and 0.1 millimeter wide and the solder pads you solder them to are even smaller. Fortunately the caps in the ECU can be done with a 4X power glass on a articulating mount. Steady nerves and good soldering equipment along with a good supply of cuss words helps.
Hi folks: As a non-computer user, I'm getting frustrated. My LS400 needs new ECU capacitors. I envy those of you who can do such work, and certainly appreciate all of the info on this subject, but I have yet to run across information as to WHERE I can send my ECU for the repairs YAMAE recommends.
So please provide me with a list of known-good repair shops who use these correct replacement parts.
Hi folks: As a non-computer user, I'm getting frustrated. My LS400 needs new ECU capacitors. I envy those of you who can do such work, and certainly appreciate all of the info on this subject, but I have yet to run across information as to WHERE I can send my ECU for the repairs YAMAE recommends.
So please provide me with a list of known-good repair shops who use these correct replacement parts.
After haunting junk yards for a few years and being usually disappointed I found a vendor online who had a California speced '94 LS400 ECU. It had a label Remanufactured for Toyota in place of the original label and with warranty stickers dated 1/19/2018 sealing the covers. The vendor told me he had got it from junk yard scavengers and was reluctant to remove the stickers. I bought it with a 3 month warranty with the understanding that I would test it thoroughly and keep it if no problems arose and he would take it back if there were any failures. No problems until this week 11/12/2019 the car started stumbling a few times when coming off idle....bad sign. Warranty period over so I broke the seal and inspected the unit. The rework quality was outstanding but on examining the 8 notorious caps I found they were the original Nichicon units! There was no leakage or board damage. There were quality assurance inspection stamps on the unit so I believe they did a good job but was puzzled as to why the original caps were used in the remanufacture. I replace the Nichicons with good United Chemicons that Yamae and LSCowboy had recommended. It runs fine and I fully expect it to work having repaired several ECUs over the last few years that showed no cap leakage or board damage. Can Yamae or anyone else speculate what happened here? Would Toyota spec the old caps in the remanufacture or just allow the rebuilder to pick the parts as long as the units passed the acceptance test?
After haunting junk yards for a few years and being usually disappointed I found a vendor online who had a California speced '94 LS400 ECU. It had a label Remanufactured for Toyota in place of the original label and with warranty stickers dated 1/19/2018 sealing the covers. The vendor told me he had got it from junk yard scavengers and was reluctant to remove the stickers. I bought it with a 3 month warranty with the understanding that I would test it thoroughly and keep it if no problems arose and he would take it back if there were any failures. No problems until this week 11/12/2019 the car started stumbling a few times when coming off idle....bad sign. Warranty period over so I broke the seal and inspected the unit. The rework quality was outstanding but on examining the 8 notorious caps I found they were the original Nichicon units! There was no leakage or board damage. There were quality assurance inspection stamps on the unit so I believe they did a good job but was puzzled as to why the original caps were used in the remanufacture. I replace the Nichicons with good United Chemicons that Yamae and LSCowboy had recommended. It runs fine and I fully expect it to work having repaired several ECUs over the last few years that showed no cap leakage or board damage. Can Yamae or anyone else speculate what happened here? Would Toyota spec the old caps in the remanufacture or just allow the rebuilder to pick the parts as long as the units passed the acceptance test?
Before I comment, I just need to ask you a question.
Are those Nichicon capacitors printed PF(M) or PR(M)?
Nichicon had discontinued to manufacture those P series that were containing the quaternary ammonium salt almost 2 decades ago and it has not been available since then except the market stock. But Nichicon has been manufacturing newer capacitors that replace P series without using the quaternary ammonium salt. I imagine those ECU's capacitor you found were not P series.
Hi Yamae. The caps are labeled PF(M). I take it then that the new caps that I replaced were good. If that is the case could it be that the few stumbles that happened were the result of water in the gas or do you think that something else is happening? Before replacing the ECU I tested all the sensors using my Lexus shop manual and all tested good.
Yamae, I should also mention that the car stumbled 2 times and did not stumble again for 180 miles of highway and local travel. I guess I jumped the gun by getting inside the ECU and replacing the caps but I know from experience that ECU troubles seem to begin with intermittent stumbles. I guess I should keep watching for any additional stumbles before declaring victory with this reworked unit.
I thought I’d share my experience of re-capping my ECU. My car is a 1998 model, RHD, with 156,000 miles on the clock.
Generally the car has been running fine, although on a few occasions recently I’ve been aware of a brief sulphur smell (not from me!), and over the last couple of years the front demister switch has flashed for a few seconds once or twice – which I understand signifies the climate control system resetting itself. Also, within the last week or so, I thought the car was holding back somewhat (accompanied by a bit of engine vibration) although this happened only the once.
I was fortunate enough to be successful in saving a non-running, pristine LS400 from the scrapyard a few years ago, simply by re-capping its ECU. (I had not expected this to work, TBH.) I wrote about it on here at the time.
So once again, I spent many hours studying the datasheets, looking at what was available, and – once again – settling on the Rubycon ZLG and RX30 ranges.
I did not replace the [Nippon Chemi-Con] 47/25 bi-polar, nor the 330/35 (Panasonic FZY Series on which I can find no information). I was able to obtain 330/35 in Rubycon ZLJ, which has a ripple rating of 1.96A, although I cannot say if its performance exceeds that of the original. It almost certainly does, but I didn’t want to risk it.
Removing the ECU was a nightmare. The diagram (which is commonly found on the Web) appears to be for 1995-97 US models. In this case however, there are extra parts/modules to contend with – including a bracket that holds a reddish-brown box. (I ended up taking out the CD player fascia, in order to remove the “green box” so as to give better access to the upper fixings. (Nobody told me about this!) All of these things are easy when you know how; seemingly impossible when you don’t. There’s a YouTube on removing the CD fascia, but there’s some sleight-of-hand in that video, so beware.
With hindsight I’d suggest you allow a full day for removal of the ECU (particularly at this time of year where it starts getting dark at 3 o’clock – in the UK at least). Believe me, you’ll be spending most of that time standing on your head in the footwell, practising your vocabulary. Park facing away from the sun (if there is any).
I won’t reiterate the importance of taking ESD precautions, as that has already been covered adequately in the initial post.
Lifting the lid revealed a couple of surprises. First of all there’s just the one board, so there’s no need to fret about fracturing those ribbon cables. Second, there was not even a trace of electrolyte leakage anywhere, nor any sign of distress (i.e. bulging) of any of the capacitors. However, the 330/35 Panasonic with that dark blue sleeve looks just like the type that I’ve seen leak in storage (and it’s flush to the board so you can’t see under it), so if I’m a little uneasy about anything, it’s that.
I’ve drawn up a table of old vs. new capacitors and their characteristics (pdf, attached). Make of this what you will. Basically, only two that I pulled exceeded the original spec for ESR (and whether or not that was detrimental, who knows?). Caps were measured on one of those “test everything” boxes that you get as a kit on eBay, being so cheap as to be virtually free. (No, it has not been checked for calibration, so it’s unscientific in that sense.)
I took a few photos along the way. The red ellipses on the solder-side of the board show reworked pads after cleaning. (I did not reapply any tropicalizing varnish.)
I will repeat that you should not attempt this job if you do not solder professionally, or if you do not have a desolder station (Pace, Weller etc.). The risk of damage to the board is too great. If you can’t do the work yourself, my suggestion would be to find an electronics engineer with a military or aviation background (perhaps retired), or alternatively, somebody who does component-level repairs to IT or broadcast equipment.
Anyway, refitting the ECU was only slightly less bad than taking it out. I dropped one of the upper nuts, and it clattered down behind the white nylon frame behind the kick panel. I found it eventually, but not before unclipping the sill cover and folding back half the carpet. (I had feared that it had somehow got into the sill!)
So, does the car drive any better? Hard to say. Is it any worse? Definitely not, at least. Conclusion? If you live somewhere cold, and you have a 1998 or later, with less than 156,000 miles, then you can probably relax a bit.
I thought I’d share my experience of re-capping my ECU. My car is a 1998 model, RHD, with 156,000 miles on the clock.
Generally the car has been running fine, although on a few occasions recently I’ve been aware of a brief sulphur smell (not from me!), and over the last couple of years the front demister switch has flashed for a few seconds once or twice – which I understand signifies the climate control system resetting itself. Also, within the last week or so, I thought the car was holding back somewhat (accompanied by a bit of engine vibration) although this happened only the once.
I was fortunate enough to be successful in saving a non-running, pristine LS400 from the scrapyard a few years ago, simply by re-capping its ECU. (I had not expected this to work, TBH.) I wrote about it on here at the time.
So once again, I spent many hours studying the datasheets, looking at what was available, and – once again – settling on the Rubycon ZLG and RX30 ranges.
I did not replace the [Nippon Chemi-Con] 47/25 bi-polar, nor the 330/35 (Panasonic FZY Series on which I can find no information). I was able to obtain 330/35 in Rubycon ZLJ, which has a ripple rating of 1.96A, although I cannot say if its performance exceeds that of the original. It almost certainly does, but I didn’t want to risk it.
Removing the ECU was a nightmare. The diagram (which is commonly found on the Web) appears to be for 1995-97 US models. In this case however, there are extra parts/modules to contend with – including a bracket that holds a reddish-brown box. (I ended up taking out the CD player fascia, in order to remove the “green box” so as to give better access to the upper fixings. (Nobody told me about this!) All of these things are easy when you know how; seemingly impossible when you don’t. There’s a YouTube on removing the CD fascia, but there’s some sleight-of-hand in that video, so beware.
With hindsight I’d suggest you allow a full day for removal of the ECU (particularly at this time of year where it starts getting dark at 3 o’clock – in the UK at least). Believe me, you’ll be spending most of that time standing on your head in the footwell, practising your vocabulary. Park facing away from the sun (if there is any).
I won’t reiterate the importance of taking ESD precautions, as that has already been covered adequately in the initial post.
Lifting the lid revealed a couple of surprises. First of all there’s just the one board, so there’s no need to fret about fracturing those ribbon cables. Second, there was not even a trace of electrolyte leakage anywhere, nor any sign of distress (i.e. bulging) of any of the capacitors. However, the 330/35 Panasonic with that dark blue sleeve looks just like the type that I’ve seen leak in storage (and it’s flush to the board so you can’t see under it), so if I’m a little uneasy about anything, it’s that.
I’ve drawn up a table of old vs. new capacitors and their characteristics (pdf, attached). Make of this what you will. Basically, only two that I pulled exceeded the original spec for ESR (and whether or not that was detrimental, who knows?). Caps were measured on one of those “test everything” boxes that you get as a kit on eBay, being so cheap as to be virtually free. (No, it has not been checked for calibration, so it’s unscientific in that sense.)
I took a few photos along the way. The red ellipses on the solder-side of the board show reworked pads after cleaning. (I did not reapply any tropicalizing varnish.)
I will repeat that you should not attempt this job if you do not solder professionally, or if you do not have a desolder station (Pace, Weller etc.). The risk of damage to the board is too great. If you can’t do the work yourself, my suggestion would be to find an electronics engineer with a military or aviation background (perhaps retired), or alternatively, somebody who does component-level repairs to IT or broadcast equipment.
Anyway, refitting the ECU was only slightly less bad than taking it out. I dropped one of the upper nuts, and it clattered down behind the white nylon frame behind the kick panel. I found it eventually, but not before unclipping the sill cover and folding back half the carpet. (I had feared that it had somehow got into the sill!)
So, does the car drive any better? Hard to say. Is it any worse? Definitely not, at least. Conclusion? If you live somewhere cold, and you have a 1998 or later, with less than 156,000 miles, then you can probably relax a bit.
Have a look at the pictures and enjoy!
Regards your ESR measurements being out of spec. Normally cap manufacturers spec the max ESR one can expect unless otherwise stated. In the case of certain switching regulators the ESR can determine one of the break points of the stability network and if too low it can affect the stability of the power supply. There are 2 ways a designer can stabilize the supply if the ESR is too low. One is to use a cap with an order of magnitude lower ESR and then insert a precision resistor in series with the cap to insure the Bode plot indicates stability. Another is to pay a premium to have the cap vendor sort for a limited range of ESRs that will insure stability. Since none of us have a schematic we can't determine what type of switcher and see the compensation network so that we could fix it by reverse engineering.
The task of removal and insertion of the ECU is the worse that I have seen. The instrument panel isn't this bad.
Just noticed that your ESR values were too high. Same problem but in this case you could definitely have a stability problem with excessive ripple under certain input (12 VDC) voltage variations, load conditions,or even temperatures if the power supply was marginally stable.
ESR measurements were out-of circuit. Through-hole desoldering with a manual tool is OK on single-sided boards, but can be risky on multi-layer boards such as this. The last thing you want to do is pull out the through-hole plating. And here, the component leads are anchored flat to the lands, requiring extra care.
Re. instability caused by too low an ESR value, this is interesting. We are presuming they are for decoupling or bypass - in which case I would think the lower the better. Given the gauge of the loom wire, I'd expect to see a couple of Ohms source anyway. (And inside the ECU, we don't know where those high-power resitors are in the circuit, do we?) What is to suggest there's a switching inverter in the ECU?
Fortunately the car is running fine, as is (as far as I know) the one I did a while back, using the same types of capacitors.
09-27-19, 02:11 PM
