REPOST of Article from toymods.org.au by The Witzl
Well, in lieu of all the guys replacing the dodgy Nichicon capacitors in their 1JZ
ecu's, someone suggested that I have a look inside my 4age 20V ecu to see if
it too used the same Nichicon capacitors that are known to leak electrolyte and
cause performance issues in 1jz and other japanese imported engines.
I would also suggest to ANYONE with a JDM Toyota ECU in their car to open the
lid and have a look for the suspect Nichicon capacitors!
Anyway... Here is my guide for replacing the caps in a 4A-GE 20V (silvertop) ECU.
Of course, we start by removing the top lid of the ECU, by undoing the 4 screws in
the corners. There might have a dob of glue in the screw heads, just remove this
with a pick of some sort.
Now you have the ECU open:
Immediately, I noticed a leaking cap up near the ECUs connectors. You cant quite
see it here, but there is black **** and corrosion all underneath this cap, and it's
pretty much damned the PCB (printed circuit board) tracks nearby.
Next... I wrote down a list of all the capacitor values, and their corresponding IDs
on the PCB. (near each cap is an ID no., eg. C012, C004 etc).I took that list to my
local Jaycar, and picked out some replacements.
The required caps are:
* 47uF, 63V x 2pcs - C002, C708
* 33uF, 35V x 1pc - C004
* 220uF, 10V x 1pc - C014
* 100uF, 10V x 2pcs - C017, C011
* 15uF, 35V x 1pc - C709
Shopping at Jaycar, you can buy direct replacements for all of the above, except
- 33uF, 35V...... Jaycar only stocks a 33uF, 25V. I'm taking a risk with using a lower
rated voltage cap, you should replace with a voltage rating of the same or higher.
- 15uF, 35V..... 15uF is a very uncommon value. You can combine a 10uF and a
4.7uF cap in parallel to add their capacitance. More about this later.
Now, i set myself up with a de-soldering pump, soldering iron, replacment caps,
some solder, and some PCB cleaner NA1008 .... all from Jaycar.
Now, on the underside of the ECU case, remove the cover (just like the top lid).
Now, there are 6 screws holding the PCB to the metal frame of the ECU, remove
them. On the side of the ECU frame, there are 4 screws holding the power
transistors to the metal frame, using it as a heat sink. Undo these:
Now the PCB comes out of the frame!
You dont have to do this step, but I attacked the underside of the PCB with the pcb
cleaner to remove the layer of protective lacquer. This lacquer is used to protect the
solder pads from corrosion and electrical shorts. Removing it helps with desoldering
It'll take a bit of PCB cleaner to get it off, and the pcb will start looking milky white...
dont worry, just use more cleaner!!
NOW...... we start removing capacitors!!!
This can be a little tricky if you arent handy with a soldering iron, but some patience
is always helpful. Start with one cap at a time, removing the old cap, cleaning up the
area, and replacing it with a new cap.
1. on the underside of the PCB, heat up one solder pad where a leg of the dodgy
cap is coming through.
2. Now grab the solder pump whilst youve got the iron still heating the pad, and
suck up the solder whilst it's liquid.
3. Repeat for the other leg of the capacitor
4. Now denso were bastards when they made these ecus.. they bent the legs of
the caps over to make removal a PITA. Whilst heating the solder pad, use a small
flatblade screwdriver to bend up the leg of the cap. Repeat for both legs.
5. Now, grab the top of the cap with your fingers, and whilst heating each of the
solder pads (alternate between pads to keep the heat going). The cap will slowly
but surely come out.
6. clean up the area of any excess solder and other crap
Now... fit the new cap. BE CAREFUL TO TAKE NOTE OF THE POLARITY!! The PCB
indicates which side of the cap is negative, match that up to the "negative stripe" on
the new cap. Dont get it reversed, or the new cap will blow when you power up the
See here for how to get it right. Note the negative stripe on the new cap and the (-)
mark on the PCB?
Now when you get to the 15uF nichicon cap, things get a little tricky. Get your 10uF
and 4.7uF caps, and before you fit them to the PCB, solder the legs together in
parallel. This effectively makes a 14.7uF cap! Trim off the excess legs from one of
the two, so that you only have one pair of legs left. Now fit them like so:
Now... because of the harsh vibration and whatnot your ECU will endure, its
probably a good idea to use some hot melt glue to stop this multi-cap from vibrating
and breaking the solder joint.
Now where i had that leaky cap, the PCB track was ruined. So i "replicated" the PCB
track using a piece of wire. You may not need to do this, but i'm over cautious.
Now... after replacing all the caps, i gave the PCB a quick coat of PCB laquer,
NA1002 from Jaycar.... let it dry, and put it all back together.
Note that the larger images from the original post seem to have been lost. These
small ones were all I could find on the interweb... still, better than none
Modified by jondee86 at 8:36 AM 2/6/2011
jondee86 has been a member for 735,126 days.
Give a person a fish, they eat for a day. Suggest they search before posting, and they learn a skill for a lifetime.