KZJ78 Tigris Writeup: ECU Rebuild/Upgrade with Pics

Tigris

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Hello friends!

Some of you know that I've been chasing an intermittent shift anomaly on this newly imported KZJ78. I started with the basics, connectors inspection, AT fluid flush, and AT filter/solenoids replacement. Although these measures did help reduce the frequency of the shift weirdness and certainly helped with the overall quality of transmission performance and longevity, they didn't completely eliminate the strange shifting issues.

I knew right then that the ECU was to blame. Knowing how our trucks (and many other 1990s LandCruiser) were victims of the great 90s capacitor plague, I opened my ECU half expecting to see some leaky electrolytic capacitors. Sure enough, all but one had leaked out their corrosive juice all over the PCB.

@GTSSportCoupe rightfully pointed out that I was in for a challenge (since he did have an experience repairing a similar ECU before). I started gathering up supplies to tackle this job.

Why do you ABSOLUTELY NEED to open up your ECU now?

Even if you have no issues, I highly recommend that you open up your ECU for an inspection. All electrolytic capacitors will fail sooner or later, it is just the nature of this component. But a great many of the capacitors manufactured in the 90s and early 2000s were part of the well known capacitor plague (inferior, malformulated, or flat out counterfeit batches of capacitors manufactured in the east), which cased a wave of high rate of global premature capacitor failures.

If your truck is from that era/region and you still don't have any ECU symptoms, then that is the best case scenario, as replacing the caps now before they physically leak is ideal, since it will be a trivial job compared to what I had to do. You will not have to deal with any trace repairs, missing pad, damaged nearby components etc. So do yourself a favor and replace the caps before they burst.

With that being said, recapping old PCBs is not for everyone. And not using the proper techniques and genuine components is arguably worse than leaving these little ticking time bombs in. So you are at your own risk, do your homework, or, send your ECU to a reputable specialist to do the job for you.


Tip: even if you found that your caps are not physically leaking or damaged, they could be (in fact likely are, if you have symptoms) electrically leaky. When capacitors start to go bad, they turn into resistors of sorts, and slowly degrade further and further until they fail catastrophically and damage other precious components. Remember, a KZJ7x ECU is practically unobtainium, and if you do find one it will cost you many, many hundreds or dollars. Other 70 series UCUs are not off the chopping block either.

The replacement caps:

You MUST source the correct caps from a reputable source like Digikey. No eBay or Amazon junk no matter how convenient. The market is literally teeming with counterfeit caps. The authentic caps are actually very cheap to buy from the right source so no reason to buy the shady ones.

The caps MUST have the same capacitance rating in micro farads (uF), low ECR, and the correct series, but you should consider getting higher voltage rating and higher hour/operational temp rating. I went with almost double the voltage and 5000 hour @ 105° centigrade operational temp on all the electrolytics. Japanese made Panasonic originals except for the bipolar cap as I couldn't find it from Panasonic.

Here is a map of the caps on the two boards. Looking at the board with the connectors facing you:

PXL_20220522_190756494.jpg


PXL_20220523_173514696.jpg


I bought double the number of caps and it was about $20. Look for EEU series caps from Panasonic as they are of very premium quality.

Here are the tools and supplies I used for this job. This picture is not all inclusive:

PXL_20220522_183058194.jpg


1. Soldering iron and solder wire (any good 40w and up iron will do, but make sure you have a wedge tip instead of the common conical tip on)
2. Two pairs of sharp tweezers
3. Solder suction and braid
4. High quality no-clean flux (this is perhaps the most important of all the supplies to have)
5. 30awg vanished copper wire
6. A set of magnifying goggles or a soldering microscope (I have good eyesight but I don't think I could have done it without the 3.5x magnification lenses on the goggles)
7. UV-activated trace mask and a UV light source (direct sunlight would work well too)
8. Q-tips and high concentration isopropanol alcohol
9. Wooden toothpicks
10. Sharp scapel blade
11. #2 Pozidriv screwdrivers (not Philips, don't repeat my mistake)
12. Miscellaneous small gauge insulated wire, heat shrink, heat gun
13 long nose pliers, cropping snips or nail clippers
14. 10mm socket, suitable rachet and extension
15. Glue gun, rubber sheet

(Now you probably won't need some of these supplies and tools, especially if you are doing a recap without trace repairs)

First, disconnect both negative terminals from your batteries. Your ECU sits behind the glove compartment. Just remove the compartment itself (not the lid) with the Pozidriv. The ECU is fastened up with a screw and two 10mm bolts. The ECU will have three non-interchangeable connectors attached to it.

PXL_20220522_181956165.jpg



On a bench, open the ECU using the proper screwdriver to avoid damaging the screws. I used a Philips first and paid the price and had to drill out one of the screws.

PXL_20220522_185121300.jpg


Inspect the PCBs, look for electrolytic leaks around a the electrolytic capacitors. As you can see, mine were in a bad state of disrepair.

PXL_20220520_214621927.MP.jpg


Tip: remove the PCB from the metal housing. Some screws hide behind the foam

Holding the ECU in the vertical and using the soldering iron and plenty of flux, heat up the pads of the capacitors one by one on the back side and pull them out with your fingers from the topside. Be gentle and take your time. When all the caps are out, inspect the traces under them, and use q-tips with IPA to clean the areas and remove the gunk and corrosion. The more stubborn bits will need more IPA and a delicate scrub with the toothpick. Take pictures of your progress for reference.


If you encounter corroded or entirely missing traces (like mine) then you will need to use your eyes and a multimeter to very carefully trace each damaged or missing trace and then scrape off some of the OE trace masking near the damage area using the scapel to reveal good copper. Do this on both sides of the damaged trace. Now drown the copper on one side with flux and lightly tin it with solder. Lay your 30awg wire (or bigger guage if you can get away with it) parallel to (on top of) the tinned part and with more flux, fuse it to the tinned trace with the iron. Route your wire to where it needs to go and repeat. When you verify that everything is correct and nothing is shorting go ahead and lay your UV trace mask where needed with a toothpick and cure it with UV light.

Move to other damaged spots methodically so you don't work yourself into a corner (many of the damaged traces were in clusters, and many were as thin as human hair) When everything checks out, cure the repaired traces in with UV mask and prep the capacitor through-holes for cap installation.

PXL_20220522_223255529.MP.jpg


PXL_20220523_000821809.jpg



Minding the polarity on the polarized caps, install the caps one by one starting with the smaller ones. Crop off the extra length of the caps' legs after you solder them in. Since we are upgrading to higher voltage/temp caps, the larger, upgraded caps will foul the top PCB if not laid to the side. Verify that the boards close down properly without shorting anything. I used rubber sheets and hot glue to secure some of the larger caps and prevent rattling.

PXL_20220523_181729428.jpg


PXL_20220523_201653681.MP.jpg


Clean the entire board with an ultrasonic cleaner (mine quit working as soon as I turned it on of course) or IPA and q-tips. Double check everything and then reassemble the ECU. Reinstall the ECU, reconnect your batteries and crank up the truck. When you reach op temps, go for a drive and you will find that your transmission is shifting like a swiss watch!

This repair/upgrade instantly solved my AT mis-shifts and improved the speed of the crank-to-start time and really smoothed the idle as a bonus! The truck drives like it has a modern and a healthy drivetrain now.

Hopefully your caps are still intact!


Cheers!

Moe.
 

Tigris

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Wow, very impressive to see the multi-faceted talent on this forum, dealing with things I would never even imagine tackling. Good job and thank you for sharing!
Thank you @janyyc you are very kind. You are correct about all the talent we have on this forum but I am certainly not one 😆. I just know that everything is figuroutable if you don't rush things and do your homework lol.

With that being said, I do believe that a preventative replacement of the caps should be high on anyone's list on vehicles of this vintage and region. I wish I had this vehicle in my possession sooner to do the job before the leak but I just imported the thing less than a month ago.

Cheers!
 

Tigris

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Lucky bunnies 😆

Yeah if your ECU/ECM/TCM etc is not included in the capacitor plague then you may be fine for a long time. All electrolytic caps fail with time and likely before other components on a PCB. I even contemplated replacing them with tantalum caps but unfortunately those don't seem like they would work for this application.

While I was researching the caps issue, I was also researching options for alternative ECUs. Since the KZJ7x uses the ECU for both engine and transmission management, the options are very limited. With that being said I will try to find a viable alternative (either an flashable EPROM based unit or a close, modified Toyota cousin ECU, or try to find more info on a possible successful 1KZ ECU simulation I hear about online.
 
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I'm not sure I'm ready or qualified to do this myself. A couple questions:

1) Where would I find a qualified person to do this for me and what's a ballpark cost?

2) If I try this myself and end up shooting myself in the foot, how hard is it to find replacement ECUs and what would that cost me?

I've done some electrical work on cars, but only "rough" work like wire splicing, never detailed circuit board work. I'd only be willing to tackle this without a known problem if I know I have a good escape route should my skills prove a little too crude.
 

Tigris

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@kgrove

Since I did the job myself, I don't know of a specific person who is qualified to do the job that is willing. I do know that @GTSSportCoupe is qualified and have performed this very procedure before I did. But I can't verify if he is taking orders.

With that being said. I do know that there are companies that are specialized in recapping ECUs that use a mail-in-service. I can't speak for their quality of work or the source of components they use. IIRC they charge something like $200-$500 and may or may not accept oddball or uncommon ECUs.

Depending on your ECU condition, this job could range from trivial (for recap with no trace repairs) to very challenging (for extensive, sub-24 gauge trace repairs). I would say if you were very gentle with your residue cleaning and use a good flux you can always re-repair your traces.

The KZJ7X ECU is practically unobtainium, and will cost north of $700 if found. I am in the process of identifying modifiable OE ECU candidates in order to find a new source for these ECUs. I am currently deployed overseas but I am looking for options around.

Cheers

Moe
 
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@kgrove

Since I did the job myself, I don't know of a specific person who is qualified to do the job that is willing. I do know that @GTSSportCoupe is qualified and have performed this very procedure before I did. But I can't verify if he is taking orders.

With that being said. I do know that there are companies that are specialized in recapping ECUs that use a mail-in-service. I can't speak for their quality of work or the source of components they use. IIRC they charge something like $200-$500 and may or may not accept oddball or uncommon ECUs.

Depending on your ECU condition, this job could range from trivial (for recap with no trace repairs) to very challenging (for extensive, sub-24 gauge trace repairs). I would say if you were very gentle with your residue cleaning and use a good flux you can always re-repair your traces.

The KZJ7X ECU is practically unobtainium, and will cost north of $700 if found. I am in the process of identifying modifiable OE ECU candidates in order to find a new source for these ECUs. I am currently deployed overseas but I am looking for options around.

Cheers

Moe
I have a 95 prado kzj78 with intermittent crankshaft position sensor issues .I replaced the sensor and still the same issue soI sent my ECU to relentless motorsports TX for a rebuild .I had the replacement Denso ECU - So at some point in its life it replaced the oem toyota pne.My conversation with Relentless ,he said it was a common problem and the rebuild should fix it.$400 later and all plugged back In nothing has changed - I am at a loss here .The crankshaft sensor check engine light comes on after she warms up .It's an automatic .When I am about to take off from a light or the end of my driveway the check engine light will go off and I have power through 2nd and 3rd sometimes and then the light comes back on and a power loss - same happens when I approach any inclines - I have been searching the forums and haven't found anything yet - any ideas or someone you could point me too to resolve this issue?Great write up by the way
 

Tigris

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@MIKADO Z

Thank you for your comment.

My shifting anomalies we're all fixed with the ECU recap. I didn't have any lights coming on, just a sporadic inability to shift from 2nd to 3rd, and a much more common inability to shift to 4th. The truck was randomly downshifting one gear without changes in load.

Although I am not certain, but I am suspecting that your fuel cut-off is being erroneously triggered. What you are describing sounded like a 'limp mode' is being triggered at the ECU by a faulty sensor.

I am not sure which sensor is responsible for boost pressure on the 1KZ, a MAP sensor perhaps?

Someone with more knowledge should be able to help here. Don't give up, usually these issues are easily corrected once the fault is identified. Best of luck!
 
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@MIKADO Z

Thank you for your comment.

My shifting anomalies we're all fixed with the ECU recap. I didn't have any lights coming on, just a sporadic inability to shift from 2nd to 3rd, and a much more common inability to shift to 4th. The truck was randomly downshifting one gear without changes in load.

Although I am not certain, but I am suspecting that your fuel cut-off is being erroneously triggered. What you are describing sounded like a 'limp mode' is being triggered at the ECU by a faulty sensor.

I am not sure which sensor is responsible for boost pressure on the 1KZ, a MAP sensor perhaps?

Someone with more knowledge should be able to help here. Don't give up, usually these issues are easily corrected once the fault is identified. Best of luck!
I did a full service to her when she arrived ,timing belt ,water pump ,all fluids ,oils ,coolants and filters - this issue has been here since I got her and I can't go on any trips til I resolve it .Very expensive machine just sitting in the garage .One suggestion I got was taking out the injectors and have them serviced or replaced - not sure if this would even be related to the problem or not -
 

Tigris

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I did a full service to her when she arrived ,timing belt ,water pump ,all fluids ,oils ,coolants and filters - this issue has been here since I got her and I can't go on any trips til I resolve it .Very expensive machine just sitting in the garage .One suggestion I got was taking out the injectors and have them serviced or replaced - not sure if this would even be related to the problem or not -
Yeah that is certainly not fun. These trucks are really good and reliable, but just like anything else that is old, some parts start to fail. I don't think the injectors are to blame (although a replacement/rebuild is never a bad idea) mainly because I understood that the truck is idling okay and still drives fine intermittently. The check engine light is also a reason to think away from the injectors IMHO.

Are you confident that the timing belt job was done right? ALL marks aligned?

Diesels rev and "throttle" by varying the amount of fuel, not air, introduced. A loss of power feels like a cut in the fuel, triggered by the ECU as a protective measure, i.e. limp mode. I would test all the sensors involved with a meter.

Moe
 

Tigris

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I am currently overseas away from my truck. But I did a quick search and the 1KZ MAP (manifold absolute pressure) sensor is on the side of the intake manifold closer to the front of the vehicle. There should be an online guide on how to test one with a multimeter.

My theory is (although I could easily be wrong) is that your MAP sensor is thinking that you are exceeding 14.9 psi and is telling your ECU to cut fuel off for protection, hence the power loss.
 
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I am currently overseas away from my truck. But I did a quick search and the 1KZ MAP (manifold absolute pressure) sensor is on the side of the intake manifold closer to the front of the vehicle. There should be an online guide on how to test one with a multimeter.

My theory is (although I could easily be wrong) is that your MAP sensor is thinking that you are exceeding 14.9 psi and is telling your ECU to cut fuel off for protection, hence the power loss.
I will look for that and check - the powerless is accompanied by the check engine light coming on and throwing the same crankcase position s3nsor code - have checked it a bunch of times to see if it has changed -
I will try that just got a new multimeter and need to get batteries for it - then I can test it .Thanks for your replies and recommendations- I will try this and let you know how it goes
 

Tigris

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Best of luck.
Again, the crankcase position sensor related code could be a manifestation (symptomatic) of the outcome of a separate issue, like a different fault causing the crankcase to "think" it's malfunctioning. Please remember this is not always the case, of course.

Now the MAP sensor appears to be very accessible and cheap (aftermarket). Maybe it's worth buying one online and sending it back if it wasn't the culprit. I think I saw them on Amazon lol.
 
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Best of luck.
Again, the crankcase position sensor related code could be a manifestation (symptomatic) of the outcome of a separate issue, like a different fault causing the crankcase to "think" it's malfunctioning. Please remember this is not always the case, of course.

Now the MAP sensor appears to be very accessible and cheap (aftermarket). Maybe it's worth buying one online and sending it back if it wasn't the culprit. I think I saw them on Amazon lol.
Since you looked it up do you have that part# handy?TIA!
 

Tigris

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Since you looked it up do you have that part# handy?TIA!
Lol, unfortunately I don't have the PN. I was only going with the Google search results for shopping. The MAP sensors I saw did look like the one on a 1KZ-TE though. Sorry!
 
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Best of luck.
Again, the crankcase position sensor related code could be a manifestation (symptomatic) of the outcome of a separate issue, like a different fault causing the crankcase to "think" it's malfunctioning. Please remember this is not always the case, of course.

Now the MAP sensor appears to be very accessible and cheap (aftermarket). Maybe it's worth buying one online and sending it back if it wasn't the culprit. I think I saw them on Amazon lol.
Sorry I am driving and dictating to the cellfone - can't be looking up parts whilst in motion lol -I will check it when I get home
Lol, unfortunately I don't have the PN. I was only going with the Google search results for shopping. The MAP sensors I saw did look like the one on a 1KZ-TE though. Sorry!
Thanks!
 

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