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AKATV

450ES ECU Blows Ignition Fuse

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Heres my wacky 450ES ECU a few days ago- a bit of a rant...

 

Got a box of parts of old ebay 98-01 450ES  leftovers and modules/harness etc that I wanted to sort and test out (trying to get organized-ha)

I have a stripped down, running  '99 450ES- out back that just needs to be put back together(sound familiar) perfect for testing odds and ends

Shoved the carb into intake boot, ran a test tank and got it fired up and warm for a bit (not bad for 15 degrees) adjust idle, tested ES shifting etc, all was well

Swapped out 3 cdi, all good-hooray!, a couple fan controls, 1 good 2 bad (gonna chuck em in the oven when wifes not around lol)

3 voltage regs, one was bad(no spark,shorted) 2 good- feeling good all is well and its starting to snow- yay I  like snow

Have 3 ECU, test one-all good, test the next one- engine wont start, shift buttons wont work, speedo shows a dash instead of N

and both the Neutral light and Reverse light are on- ok must be bad ECU with all that craziness...

Put the good ECU back in, same thing -great, did i just blow my good ECU? grrrr

Follow logical no start troubleshooting and find that I have no spark now, check fuses, swap CDI, check coil-its good

Spent a good deal of back and forth scratching my head and fumbling for a good hour

I check the fuses a 3rd time, snow is ticking me off now....lol

So on my THIRD fuse check (I was only checking the IGN fuse) I realized my fuse count was off because you know when you read the inside of the fuse cover

it reads- SPARE-IGN-FAN-LIGHTS-....etc,  well  I noticed withhelp of a flashlight, the slot for the spare was empty and I was counting the IGN fuses as the SPARE

and found that the ECU had indeed popped the IGN fuse

Put original ECU back in put 10 amp fuse in and had spark now, started back up and all was normal again

turned off, put questionable ECU in and quietly turned key on and you could hear fuse pop

Pulled bad ECU, replaced fuse and put 3rd ECU in and all was good, shifting etc.. yay all is good, loving the snow again

Felt stupid but was happy to find I had not smoked a good ECU..

 

So, an ECU can short internally and pop your IGN fuse-never seen it before

and even crazier, when you pop or pull your IGN fuse, your gear position will read dashes ----,

your shift buttons will not work AND your neutral light and reverse light will be on at the same time

and you lose spark- lol

 

Yes, I now have a spare 10 amp fuse back in place in the fuse blocks spare position, lesson learned

 

Ever see the inside of an ES  ECU?

Think I am going to cut this one open and see if I can find what failed....

 

 

Edited by AKATV
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Thanks for sharing! I'm looking forward to your ECU repair!

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Would love to see what's in an ECU as well.  I have a couple for the 500's that no longer turn the fan on (when I bought the machines the prior owners had straight wired the fans)

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I really think inside is just a circuit board that is covered in epoxy that is going to be a nightmare to clean enough to see anything, but after the pain I went thru troubleshooting, I think there will be some satisfaction on cutting it open- lol (insert crazy mad scientist laugh)

I do want to see the point of failure though, so I can try and figure out what caused it.

 

I have had very good luck reviving non working fan control modules and even an occasional CDI on the 450's by reflowing them in the oven @ 425-450 degrees for 7-10 minutes then let cool down without moving it at all.

Wait till wife is gone before putting in the oven-it will smell up house like cooking plastic, sometimes the back side epoxy filler will split from the heat, no big deal you can just seal with whatever s on hand -RTV, JB Weld etc...

Once it cools down it either works or it doesn't, lol , also give it 2nd try before you toss it out

I have some friends fan controls that are still working 12 years after "cooking"

The solder joints and circuit board traces break down inside the module from the heat/cold/vibration cycles and start to have intermittent contact, then eventually they fail, as they dont touch anymore

This is why knocking on a non sparking CDI module will get it to spark sometimes-

Reflowing re-melts the solder joints and will take care of the problem most of the time, I would say better than 75%

Not sure on the Foreman 500 ECUs, but I think they are combined all into one module, but if its not working, just sitting around, it might be worth a shot- but I wouldn't pull one to cook it that has  a fan wired in, in case it kills it

 

Also just a note- cooking them is worth try for non working or intermittent modules, but one that is shorted internally like mine and popping fuses has an a failed component inside that cannot be fixed by reflowing the solder joints

 

 

Edited by AKATV

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21 minutes ago, AKATV said:

I really think inside is just a circuit board that is covered in epoxy that is going to be a nightmare to clean enough to see anything, but after the pain I went thru troubleshooting, I think there will be some satisfaction on cutting it open- lol (insert crazy mad scientist laugh)

I do want to see the point of failure though, so I can try and figure out what caused it.

 

I have had very good luck reviving non working fan control modules and even an occasional CDI on the 450's by reflowing them in the oven @ 425-450 degrees for 7-10 minutes then let cool down without moving it at all.

Wait till wife is gone before putting in the oven-it will smell up house like cooking plastic, sometimes the back side epoxy filler will split from the heat, no big deal you can just seal with whatever s on hand -RTV, JB Weld etc...

Once it cools down it either works or it doesn't, lol , also give it 2nd try before you toss it out

I have some friends fan controls that are still working 12 years after "cooking"

The solder joints and circuit board traces break down inside the module from the heat/cold/vibration cycles and start to have intermittent contact, then eventually they fail, as they dont touch anymore

This is why knocking on a non sparking CDI module will get it to spark sometimes-

Reflowing re-melts the solder joints and will take care of the problem most of the time, I would say better than 75%

Not sure on the Foreman 500 ECUs, but I think they are combined all into one module, but if its not working, just sitting around, it might be worth a shot- but I wouldn't pull one to cook it that has  a fan wired in, in case it kills it

 

Also just a note- cooking them is worth try for non working or intermittent modules, but one that is shorted internally like mine and popping fuses has an a failed component inside that cannot be fixed by reflowing the solder joints

 

 

 

Well thus far the two I've had with bad fan controllers I replaced with good ones out of my parts stash.  The bad thing about that is, I'm left without spare ECUs...unless I want to use one with a bad fan module. 

 

Maybe I'll take an old toaster oven out to the shop and try cooking one.  What do I have to lose, right?

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It would be good to try one to have a fully working ECU at least (maybe)

Just want to be careful with temps and time- dont know how accurate toaster oven temps are

Its not super critical, but you want to be close

If you have a way to measure temps that would help

I have one of the laser temperature guns for checking engine, head and exhaust temps etc

it works really good for monitoring temps

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seem's too me ?..all your prob's is cuz yer working on a es model !..rofl.

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Ha-ha Shade  I knew it was coming- I know you hate 'em 

Up here in Alaska there is an abundance of The ES models and once you swap out the gummed up shift motor grease,they are a great dependable machine

 I have only seen  the occasional  bad angle sensor and only recently found a bad ECU in my parts pile (and a blown fuse lol)

People tend to ride the automatics and ES models more in Winter time here as its hard to foot shift with a big 'ol snow covered vapor barrier style (Mickey Mouse) boot in Arctic temps

Plus the ES model is a great option for disabled riders and people with injuries (no toes due to frostbite) that can't use a foot shift ATV properly

Some have tried adding hand shifter on foot shift models, but not so much when you have to keep taking a hand off the steering in snow and ice- lol

 

Edited by AKATV
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I can't wear my one set of boots for that reason, can't shift gears with the big boots on in the winter...

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When I worked offshore in the early eighties we would soak capacitors in something like varsol . The next morning you would see a tiny droplet of sea water at the bottom of the container and it would usually work again. Later after I went into business for myself an old 1981? YZ250 came into the shop with no spark. I soaked the stator overnight in gasoline (No mineral spirits) and it worked!.

Edited by Misterclean
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