4A-GE 20V Capacitor replacement. (56K ouch)

[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.

Well.... they were right. *Thank you JP for the suggestion.

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 shit and corrosion all underneath this cap, and it's pretty much fucked 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 two.
- 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.
Now, 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!

Next.....
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.

To remove:

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 ECU.

See here for how to get it right. Note the negative stripe on the new cap and the (-) mark on the PCB?

[The Witzl]

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.





BANZAI!!

[Poggy]

any diff is how it runs?

[The Witzl]

yes, it has improved things a bit.

Most noticiable is a smoothing out of idle. Whereas before the idle would drop, raise, and occasionally stall the engine... it is now a lot more controlled and consistent.

I would definitely recommend opening your ECU poggy, im pretty sure your AE101 ecu has the same caps

[Poggy]

yes, it has improved things a bit.

Most noticiable is a smoothing out of idle. Whereas before the idle would drop, raise, and occasionally stall the engine... it is now a lot more controlled and consistent.

I would definitely recommend opening your ECU poggy, im pretty sure your AE101 ecu has the same caps

During heavy rain one night a while back i went through a dip that had heaps of water, car stalled, had water in the car above the door seals, pushed out of the puddle, tryed to start NO GO, remeber the ECU sits on the floor, lifted it up and shacked it, got it started, took it home open it up, blew it out etc, wanna do it for me? LOL

[Sam_Q]

thanks for the article I have been chasing my tail for ages now trying to figure out whats wrong with mine, maybe this is it?

[Talasas]

Very nice work there. I have a couple of questions:

1: You mention this is for the Japanese ECUs, is that implying the ADM 4A-GE ECUs used locally manufactured parts?

2: You replace a 15µF cap with 14.7µF combined caps, I understand the concept of Standard values but just out of curiosity was this because it was too difficult to find a 15µF cap? Also do you know what part of the circuit by any chance this buffers? Not so much concern as it is curiosity I should stress.

[The Witzl]

Sam - open your ecu and check it out. In particular check the larger cap just near the ECU connectors, its the same one that usually goes on 1JZ ecus.

Talasas...

1. Yep, Aussie ECUs dont seem to use the dodgy Nichicon caps.
2. 15uF is a very uncommon value, so without paying retarded prices plus shipping from places like RS or Farnell, you aint got much luck. You could pinch one out of an ADM ecu probably. As for what circuit it's related to... i gots no idea. Maybe i'll check that out.

[The Witzl]

just added the correct capacitor values in the first post

[Sam_Q]

I will do just that, thank you once again

[JP]

it's also worth noting that on some caps you can't tell they've started leaking until you remove them.

Pics of two sets removed from 1J ECU's:
http://users.tpg.com.au/adsl0uxv/caps1.jpg
http://users.tpg.com.au/adsl0uxv/caps2.jpg

[takai]

Hm, sounds interesting. Should open up my 2JZ ecu and have a peek before i bother to put it all in.

[The Last Streetfighter]

Karl you bastard.

My engine's identical to yours (even down to the undecided idle...but then I've not cleaned my ISCV yet (Awaiting your Silvertop ISCV Cleaning thread)) and runs "perfectly" but now you have me thinking that I have a ticking bomb. I will take the ECU out, look at it and be not game enough to fix it despite your tutorial. :@

Lol +rep anyway.

[Vios-GT_07]

would you be willing to fix mine anyway?

i'll send you my ECU, send you some money, you fix and send it back to me?

Witzl's ecu service and maintenance?

[broken22]

I use acetone at work to remove the conformal coating from the PCB (almost like nail polish remover).
I would also recommend doing this wearing an anti-static strap, to protect the ECU.
Solder braid and Flux is another effective way unsolder.