All my crazy Lexus issues SOLVED!! (ECU-leaking capacitor)
10-26-13, 05:49 PM
#526
Lexus Champion
Thread Starter
if you will take a high resolution photo of the instrument cluster and also provide a list of what caps you see on it, I will make sure you didn't miss any caps and give you recommendations on the best replacement cap for each one.
10-26-13, 06:05 PM
#527
I believe they are surface mount capacitors which means that the fix will be far from easy!
(and somewhat of a hack job since I'd be mounting through hole capacitors in a place where SMD capacitors should be..)
10-26-13, 07:00 PM
#530
*removing old capacitors
when you have the bare circuit board on your bench, and begin to remove the bad C142/C147, DO NOT just pull the capacitors out. Be very careful not to damage the circuit trace surrounding them. the capacitor can is surface-mount on the component side of circuit board, and you can’t de-solder it from the bottom of circuit board. the two legs (+/- leads) are too short (entirely covered by the ‘can’) to be de-soldered underneath the capacitor can. What I did was to use a sharp nose pliers and ‘destroyed’/removed the capacitor can first, then the two leads were exposed to be de-soldered.
when you have the bare circuit board on your bench, and begin to remove the bad C142/C147, DO NOT just pull the capacitors out. Be very careful not to damage the circuit trace surrounding them. the capacitor can is surface-mount on the component side of circuit board, and you can’t de-solder it from the bottom of circuit board. the two legs (+/- leads) are too short (entirely covered by the ‘can’) to be de-soldered underneath the capacitor can. What I did was to use a sharp nose pliers and ‘destroyed’/removed the capacitor can first, then the two leads were exposed to be de-soldered.
10-26-13, 08:09 PM
#532
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10-27-13, 02:44 PM
#534
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I completed my 1992 sc400 ecu succesfully all with caps purchased through Digikey and the 10uf 50v through mouser. I purchased enough for my 1995 LS400 and my 2001 Tundra. I realize you haven't listed the 2uzfe is the original post but I have a hard 1st to second shift bang. Slippage from 3rd to 4th, hard starting and horrible fuel mileage. Actually, its probably good to add that in addition to the poor fuel mileage, when I replaced the starter in the Tundra, I had to pull the plenum and there was literally puddles of fuel in there. It was crazy to see this!! So I'm going to hope that the list for 1998 - 2000 is applicable to the 2001 Tundra. I'll soon find out!
10-27-13, 02:50 PM
#535
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So I'm going to hope that the list for 1998 - 2000 is applicable to the 2001 Tundra. I'll soon find out!
how is the '92 running now?
10-27-13, 05:38 PM
#537
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LScowboyLS, I had one location that had severe leakage and some bad green looking junk under the cap and on the board. I noticed the baking soda/vinegar took the conformal coat off the board so i kept it to a concentrated area of use. I will be going to the shop tomorrow evening to reinstall the ECU and test it out. I will post my results. As far as the Tundra 2uzfe ECU, I planned on opening it up and comparing the list for 1998-2000 models to what I find in there and then placing my order. If I provide a list and see capacitor values other than those listed would you be able to post links to the correct ones to buy? Here are some pics of the 1992 SC400 ECU I just completed. Oh, and lastly, the 40w iron I purchased through Radioshack crapped out immediately. It was weird, it smoked out the cord end and it would not heat up enough after that. The store accepted it as a return and I bought the 60w version. It worked flawlessly.
Last edited by dhhd; 10-27-13 at 05:40 PM. Reason: pics
10-27-13, 06:02 PM
#538
Lexus Champion
Thread Starter
with all of this leakage, you will be amazed at the difference in the car!
make sure to clean all that mess on the board up
you can just use alcohol in a pinch, and a soft toothbrush, but do not get near the very delicate surface mount components (in the photo above, see the tiny cap C102 that is orange and says A4 on it?) - those are very easy to ruin with soldering iron or toothbrush - very delicate, stay clear of them!
yes!
make sure to clean all that mess on the board up
you can just use alcohol in a pinch, and a soft toothbrush, but do not get near the very delicate surface mount components (in the photo above, see the tiny cap C102 that is orange and says A4 on it?) - those are very easy to ruin with soldering iron or toothbrush - very delicate, stay clear of them!
If I provide a list and see capacitor values other than those listed would you be able to post links to the correct ones to buy?
10-28-13, 07:18 AM
#539
I think it was probably the Arcticlean that started to remove the conformal coating!
Just proves that you need to be super gentle with these boards. When I go to finish the job, I will just upgrade to 91% isopropyl alcohol.
...and WOW, that capacitor was SHOT. None of mine looked that bad!
10-29-13, 08:08 AM
#540
1992 LS400 126,000 miles TRAC-equipped with ECU # 89661-50042
Symptom:
totally erratic Just Like Running Out Of Gas whenever it feels like it.
Spontaneously cleared up for *a whole year*, but now is cropping up monthly.
A full tank of gas seems to help. That made me think fuel pump windings getting heat-annoyed at low fuel level?
Bridged two-stage fuel pump relay, no change.
Replaced fuel filter, no change.
All grounds good.
The fact that the symptoms disappear so crisply and discretely, makes me think of things electronic . . .
But.
Removed ECU.It looks so absolutely pristine beautiful, not a speck of dust in the box, no evidence of anything having ever leaked, that I am hesitant to hack into it . . .
Pored over every solder joint:
I need to know from a definitive Graduate Of Capacitor Replacement that:
a) you *can* have a perfect circuit board staring back at you, yet bizarre symptoms.
b) perhaps some other circuit board in these cars that might be the agent behind this Just Like Running Out Of Gas symptom.
Colin
(p.s. anybody here notice that the LS400 is going *up* in value in the NADA guides?