ECU placement

ECUs, lighting, alternator, starter, dash instruments, etc., we'll figure it out.
midnight garage
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ECU placement

Postby midnight garage » 04 May 2010, 04:52

Kurt.

I am a little worried about your ECU placement.
Maybe my concern is needless, but out of experience I saw some strange things happening due to entry of moisture into control units, so don't think too light about it.
On the picture in the build diary I saw a connector on top of the ECU, which doesn't look like it is sealed for moisture.

One complaint in the field I investigated showed some undefinable errors in a control unit. We found out that moisture was entering over the hood release cable ( so not in large quantities) and entered the connectors of concerning ECU. After a span of time corrosion was visible on the pins in the connector, causing malfunctions.
See picture below; corrosion of several pins is obvious at the green/blue discoloration:

connectors.JPG


Maybe you can adapt the location of the ECU, or make sure you prevent any moisture in the surrounding area on the unit itself, the wiring and the connector.

Just a tip to prevent some undefinable errors after a period of use....

BTW .... MidLana is looking better each entry I read in the diary; great job !! Grz. Jos.
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Midlana1
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Re: ECU placement

Postby Midlana1 » 04 May 2010, 06:38

A very good point. You're completely correct about the effects of moisture on ECUs. Many (all?) are not conformal-coated, where basically the board is dipped or sprayed with a sealant. Particularly suseptable are connectors which, sealed board or not, are by necessity open to the environment.

Being an open-top car Midlana is particulary suseptable to moisture, and we're left to find the best location for the ECU given few choices. So, where can it go?

1. Under the dash. This is the best place due to the cowl acting as a roof. Unfortunately it's too far away from the engine to be practical.

2. Behind the seats. This isolates the ECU from the heat of the engine compartment, but does not protect it from moisture, particularly rain. There's also very little space, at least in my own car, due to the seat lean-back causing the seat to be very near the firewall.

3. Inside the center tunnel. This would be a great location but there's simply no room, zero, in fact.

4. Inside the engine compartment. It gets hot, though cooling air can be routed to the ECU. Most helpful is that the engine cover will serve as protection from rain.

So there are the choices. I chose #4 and will be adding a box around the ECU to ensure rain can't get in, adding an air-cooling inlet duct.

Regardless where the ECU is placed, there will always be the problem with moisture in other forms, particularly fog. One approach is a kitchen container with a snap-top lid, sealing the hole where the wires come in, but of course the ECU needs to be somewhere cool for that option.

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Re: ECU placement

Postby midnight garage » 04 May 2010, 07:13

Because I am not that familiar with Honda's.... where is the ECU located original in the donor car ??

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Re: ECU placement

Postby Midlana1 » 04 May 2010, 09:48

Passenger footwell. Being FWD it's a great location, but in our application it's a long way to the engine at the back of the car.

I guess the harness could be made longer in order to place the ECU up front, but I'm a little suspicious that doing so may introduce EMI into the wiring, and I admit to being lazy. Probably the best position is having it bolted to the forward face of the firewall, assuming there is room. But as said before, the ECU will still need a weatherproof enclosure. With it where it is now, the engine cover serves as a roof, and I may add a small box over the top of it just in case.

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Re: ECU placement

Postby midnight garage » 04 May 2010, 10:24

I agree.... for making the harness longer, I would also be too lazy. Too big a job !!

Let's hope all the efforts for making it weatherproof will do the job.

Grz. Jos.

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Re: ECU placement

Postby biped » 04 May 2010, 17:44

http://www.stabilant.com/appnt20h.htm

There are a few products out there that are supposed to enhance electrical connections and offer some weather resistance.
Which work and which don't I have no idea. Have read that dielectric grease has been the subject of a few recalls here and there.

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Re: ECU placement

Postby midnight garage » 04 May 2010, 23:15

To my opinion it's best to put efforts in keeping the water out. Maybe some kind of box like Kurt mentioned earlier is the best alternative.
Maybe the web offers some solutions, let's take a look.

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Re: ECU placement

Postby midnight garage » 05 May 2010, 00:15

Just found some interresting info about waterproofing an ECU from a japanese supplier.
It also relates to the heat build up within a waterproof box, so a membrane will be needed to let heat out. Take some time and read on the link below.
Maybe it can help us on the ideal solution....

http://www.fujitsu-ten.co.jp/english/co ... 6/26-1.pdf

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Re: ECU placement

Postby thebionicman » 06 May 2010, 20:09

I work with controls (ECUs) in a mobile (construction) environment. I would just pack the connector in dielectric grease and keep it in a spot where you wouldn't get a direct washdown.

midnight garage
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Re: ECU placement

Postby midnight garage » 06 May 2010, 23:22

The ECU's in your enviroment are probabaly constructed for such use, and will be waterproof. Kurt's ECU is for designed placement in the passenger compartment, around the A pillar, and isn't waterproof, so additional action to protect is needed. Maybe the grease idea is sufficient, but I doubt it in the long term, it will start collecting dirt also. Also the upper connector will stay open; I assume it's the connector for the PC.
Some extra effort in making it waterproof will pay off in the future. After all, the ECU will not be cheap, so it's a shame if it get's ruined by moisture.


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