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Electrical guides and mods

Canadian E-Box Failure

Modification Details




Only Canadian Smart 450s Need Apply

This is one of those faults that only affects 1 type of car. Strangely it only affects 450s in Canada.
This fact becomes less strange when you realise that the part that fails is only fitted to Canadian 450s.

Of course, that does open up the question. Why the hell did this part need adding anyway?
The smart 450 works fine as it is all over the world. Why add something else that can break?

Anyway, I digress.

Symptoms

The fault usually starts with the brake lights coming on and staying on. This creates a backfeed issue with the ESP/ABS controller which in-turn creates a fault in the transmission. This fault brings up 3 horizontal bars on the speedo LCD to let you know of a transmission fault. Then the car won't start and you are stuck.

The Part

The part that causes all of the agro is called the E-Box made by Zytek. It's in the passenger's foorwell,
behind the polystyrene block. The box has 2 plugs going in the side. Plug 1 has 22 pins, Plug 2 has 16 pins.



The photo below shows 2 E-Boxes. The right one had died, the left one was the replacement.
Notice the fabric cover for protection. This helps the water wick into the casing.



The E-Box controls all of the lighting in the car including the small binacle of lights just below the dash pods.
Again, this is another thing only found on the Canadian smart 450. If you have a photo of this, send it in.

The Problem

Due to the positioning of the E-Box, it is easily affected by water ingress if the AC drain becomes blocked.
The water wicks into the foam under the carpet and  eventually makes it into the E-Box casing.

Glenn found that his car was having brake light issues so investigated the E-Box. After removing it from
the car and taking off the top of the casing, it was clear that water ingress had caused the problem.



The water gets in down the side of the main connector and sits in the case. Due to the opening, the water level
shouldn't get any higher than this. We can therefore assume that the affected relay controls the brake lights.

The combination of static water and an electrical current causes oxidation of the copper in the PCB.
That's what causes the blue/green build up and over time, the tracks wear away and components
corrode until a connection is broken totally, a fault occurs and the car refuses to start.



The Fix

You may be lucky. If you catch the problem in time, you may be able to just remove the E-Box, clean it
with PCB cleaning fluid or electrical contact cleaning spray. Brush off the detritus with a soft toothbrush
and dry it with a hair dryer. Plug it all back in and give it a try. If it all works as it should, you are lucky.
Remove it once more and read further down the page about protecting it so it doesn't happen again.

If you have cleaned up the E-Box PCB and it's still broken, you'll need to buy a new one.
Smart part number 0019298V001000000

The new one doesn't need any type of coding but do protect it before fitting.

Protecting The E-Box PCB - Cure

Glenn decided to seal between the case and the connectors as this is where the water flows in.
The new E-Box with protection is seen on the left.



Personally I wouldn't recommend this type of protection as you can't be 100% sure that you have sealed it.
Water could still get in down the side of the electrical connection pins.

You could end up raising the level to which the water could rise before it escapes.
This will just damage even more of the tracks and components on the PCB.

I totally recommend adding protection directly to the PCB and drilling a hole in the lowest part
of the casing. That way, any water coming in doesn't affect the PCB and drains straight back out.

The best way to protect your E-Box is a product called conformal coating.
It is a clear spray that the military use on missile and submarine electrics.



It will wick underneath the sockets and chips on the board. 3 coats should be done to be sure.

Conformal coating is a clear spray so make sure you cover everything. A good
conformal coating spray is reactive to ultraviolet so you can check for coverage.

The drawback with conformal coating is that it is really quite expensive, however, with
1 can of spray you can do 5 or 6 E-Boxes so buy it, use it, pass it on to another owner.

Protecting The E-Box PCB - Prevention

What better way to stop water damage of the E-Box PCB than stopping the water being there in the 1st place?

Chances are, the water will be coming from 1 of 2 places. Either the AC drain pipe is blocked so the water is backing up inside the cabin heater box and pouring out into the car, or the windscreen is leaking. Both are common.

Have a look at this page about how to check and clear the AC drain.
Have a look at this page regarding how to check for windscreen leaks.

It is also worth checking to see if the rear carpets are wet as there is a chance that if a rear quarter window was leaking, over a long period of time, the water could eventually seep to the front of the car.

Conclusion

Don't rely on just 1 of the preventative measures above. Regularly check under the carpets for water, seal
the PCB and drill a small drain hole in the E-Box casing to allow water to drip out instead of sit in the case.

Credits

Thanks to Glenn for allowing me to use his photos.

Additional

If anyone has an old broken E-Box they could send me, that'd be helpful.
I know a lot of you Canadians speak French so if anyone wants to send me a translation, I'll put it on here.


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