I think I fried my ECU...help!

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I think I fried my ECU...help!

Postby AmericanWalkabout » Sun Jan 14, 2018 10:29 pm

Sorry for the long post but it's a long and involved issue.

I'm new to this forum and the 990 SD-R but not to the LC8 or wrenching in general, but...

A little background. I picked up an 08 SD-R just before Christmas. It joins an 07 SE-R and a 15 ADV-R in the garage so LC8 and I are fairly familiar. The SD-R had been owned by a young guy who clearly wasn't in to maintenance so I decided to pull it down and do a thorough maintenance and check on it before letting her loose on the track in mid January. While I'm in there I figured I'd do the SAS and Canisterectomy as well as check the valves, plugs, oil change, check wiring and a thorough cleaning. Bike was running well before I started, not that I rode it more than a couple of miles.

Having a decent workshop and being ok with a soldering iron I decided to make the block off plates and do the resistor mods for FI myself. All seemed fine until I realised I didn't have the correct resistors lying around and so I ordered them. And here we go. Plates are on, everything is cleaned up and ready to go back together but resistors still haven't arrived. I still hadn't done the oil change so wanted to warm up the bike to do it. I figured maybe KTM had been fooling us and the resistors weren't that important so I just wired each of the two plugs (SAS and Purge valve) with a connected wire. Not wired together, just each plug had a solid wire between each prong instead of having a resistor there too. It was only going to be temporary so I could warm it up mind you. So I started the bike, no FI light, seemed to be running better than before, and I thought damn, maybe I'll just leave it that way.

About 8 or 10 minutes into the warm up idle and the bike just shuts off. The exact sequence of events is a little foggy here but I think at that point I hit the starter button and either then or just before it died, the #6 main relay fuse blew. I replaced the fuse, hit the starter, pop, happens again. I immediately think, uh oh, resistor is important. So I removed the solid connection and figure I'll just get an FI light. Nope, keeps blowing #6 fuse and won't turn over at all.

And then it gets worse, somewhere in my frustration and impatience, I decided to hard wire the fuse (just for a few seconds the devil on my shoulder told me) to see if it would turn over at all. Instead of blowing the main fuse which somewhere in my pitiful head I had assumed it would do if there was a serious issue, it just started smoking from up in front of the tank, near the ECU. Of course I immediately stopped hitting the starter switch and pulled the tank off to see what I'd done. Couldn't see anything melted. At this point I decided to be smart about it and look at the schematic and trace where I'd clearly melted a wire(s). After a couple of days of tracing every wire and fixing a few that I was hoping were culprits, the #6 fuse has stopped blowing and I've traced the CURRENT issue down to the rear coil stick and the ECU. Within a couple of seconds of turning the ignition key on, (not even the starter button anymore) the rear coil gets hot on the outside and I hear crackling inside the ECU which also gets hot. I know it's not the coil pack itself because when I switch front to rear same thing happens, but rear in the front doesn't cause it any issue. I've checked the wiring for the rear coil pack and it seems ok as best I can see.

My questions:

1. Would straight wiring the SAS and Purge valve plugs without the resistors have caused the Main relay fuse to blow in the first place?
2. If not my non-resistor wiring of the 2 plugs, any idea what may have caused the initial issue? I don't want to get everything back together for it just to happen again.
3. Any way to tell for sure if through my impatience and stupidity I've fried the ECU? I have a TuneECU cable on order that I'm hoping may allow me to do more diagnosis (ideas on how to test?)
4. If/when I get a new ECU, will a 2011 or 2012 unit (what I've found used on eBay so far) with same part # as the one I have work in my 2008?

Thanks for any assistance, Drew.
I've been possessed by the orange demon...

2008 990 SuperDuke-R
2007 950 Super Enduro
2011 530 EXC-R
2015 1190 Adventure R

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Re: I think I fried my ECU...help!

Postby No. 47 » Mon Jan 15, 2018 5:59 pm

Afaik viewtopic.php?f=5&t=16290&p=192707&hilit=fried+ecu#p192707 is the only instance of a fried ECU on here - familiar? - as noted, all SD/SDR ECUs are same part, I think, just different maps, etc but check SD and SDR parts fiches to be sure.
'08 ex-Battle race KTM Superduke 990 R No.47
'08 OE KTM Superduke 990 R
'01 Ducati 996S

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Re: I think I fried my ECU...help!

Postby Motogoon » Wed Jan 17, 2018 6:48 pm

If it turns out any year ecu can be used I have an ecu unit for sale off a 2005 model I'm dismantling.

If you're interested let me know how much the ebay ones are going for and I should be able to do a better price

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