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Honda MICU (breakdown?)

backporch

New Member
Hello,
I have a Honda Odyssey that has some water intrusion into the cabin that has resulted in some corrosion on the MICU. I removed and cleaned the outside of the device with Deoxit, but didn't try to separate any of the internal components. I was hoping to find some guidance here if there is likely internal issues and if the internal components can be safely broken down and cleaned.

In the picture, the water entered above the green circuit board in one of 8 separate harness connectors and the corrosion also appears at the very bottom left of the component. Since there are no other openings on this module, the water entered the top and worked its way down to the bottom. I would like to break down this board into its many layers because the problem I am chasing down was not fixed by the superficial cleaning that I was able to perform.

Thanks for taking the time to read this and all comments are appreciated.

63444559937__B10A8E5B-09F4-40AF-8D3F-B2DC7E2A6A3E.jpeg
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
What can happen is the vias can get destroyed by corrosion. Usually this happens becase of the tantalum capacitor plague that happened in the 80's I think. The boards consist of many layers. I think 40 or so is the upper limit. the via may sometimes have a componenr and sometimes do not. You can have normal vias, burried or blind vias.

So check for corrosion at these holes that "go nowhere" so to speak.
 

Diver300

Well-Known Member
Most Helpful Member
You can't break a circuit board like that down to any further level. However it might be possible to remove the green circuit from the metal connectors below it.

The corrosion on the bottom left of the board is probably not important and certainly isn't severe but you could wash it with alcohol.

If there is damage it may not be visible.
 

backporch

New Member
I don't understand the vias. are those the many holes on the PCB?
The vehicle is a 2005, so manufacture of this board is probably 2004/5, if the 80s was reference to a year.

I don't want to take the board itself apart, I was thinking of taking the board off the rest of the module and cleaning its other side if needed. The board is attached with pins under the white "connector" at the top. Wasn't sure if I could just carefully pull it up and off.

I also wasn't sure the purpose of the two rows of prongs at the bottom. Seem to be too many for alignment, and if conducting something, it seems kind of crude as they are not all that straight.
 

KeepItSimpleStupid

Well-Known Member
Most Helpful Member
I don't understand the vias. are those the many holes on the PCB?
This https://www.analogictips.com/printed-circuit-boards-part-3-vias-and-multilayer-boards/ describes vias.

When a double-sided or multi-layer board is made, vias are used to connect layers. The holes are drilled in the copper and then the holes are plated thru. They make copper grow to line the holes and connect the layers.

The lower connect, the first 8 pins from the top. many pins look corroded. One pin may even be missing. Look at pin 7 and 8.
Pin 7 looks missing and shorted to pin 8
 

narkeleptk

Active Member
Liquid damage not only oxidizes joints and decays away the internal traces like KeepItSimpleStupid suggested but it also likes to corrupt the flash sector or just flat out kill the mcu's. Light liquid damage you can sometimes repair ok, Medium to heavy damage its not even worth trying. I'd suggest cloning the 93c46 you see next to the mcu to another unit with same part number. Should be plug and play then.
 

backporch

New Member
Appreciate the education here. scanned the vias link and that makes sense. is there any sense to trying to examine them for any kind of noticeable corrosion and try to treat with a deoxidizing spray?

I guess the 93c46 is an IC that may be storing something important to this module? I was under the impression that they could be replaced ,but I would not be surprised at all that some kind of data transfer is required.

is there any source that might shed more light on the data transfer for the IC?
 

backporch

New Member
The lower connect, the first 8 pins from the top. many pins look corroded. One pin may even be missing. Look at pin 7 and 8.
Pin 7 looks missing and shorted to pin 8
Here is a close up on the pins. Good eye on the other picture. I believe 8 was empty.

Are these contacts between different levels/parts in this assembly?
 

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narkeleptk

Active Member
Some are direct swaps but many of the honda micu's store some code for a link between the immobilizer & ecu and will need syncing. The 2005 vans use the older system immobilizer so it may not be necessary but I dont replace a lot of micu's so couldn't guarantee it either.
 

backporch

New Member
I just came across a clip that mounts to the IC. Very cool to be possibly able to read and write the memory on these chips. I was looking at replacing my speedometer and wonder if the odometer information can be transferred in a similar way.
 

narkeleptk

Active Member
The clips are not that good imo, They are very easy to get corrupt reads. If you use one make sure to read, verify, remove it, then clip again and with another verify . IC you can do the same on this one.
 
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