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Discussion Starter #1
I'm new to RZr's, but not new to machines. I've got a dead cylinder, 2010 RZR 800s. I'll say the front one, nearest the cab. I've checked the plug wires, good. New coil,plugs. Switched the good coil wire to each cylinder and they both fire,so I guess really what I have is half a coil, which as I said is new. Am I looking at a new ECU, or is there something else to check first.only other thing I can imagine is a wiring harness problem. I'm past mad... now it's personal...馃槑...
Any help or suggestions are appreciated ...
 

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Discussion Starter #3
Compression test?
Switched live coil wire to other cylinder, and runs fine on that cylinder too. Compression isn't a problem, it's spark. There's no fire coming off the coil for the front cylinder. My question is about the ECU. Does it send independent signals for each cylinder to the coil? That seems redundant, because on the 10's and older 800's , I'm told, both cylinders fire at the same time. Only other choice is in the harness I would think. I hate to get an ECU if I don't need one. Thanks
 

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2005 Ranger XP 800
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This is the ignition coil from my '08 RZR service manual (PM me your email and I can send it to you). The Red/Black is +12v from the EFI Power relay. The other two both go back to the ECU. From the schematic, it does send a separate signal from the ECU to the coils.

You might want to check the harness for those other two pins to see if they both make it back to your ECU. You might want to look at the wiring diagram for your bike, though I'm pretty sure 2010 is the same.

Another option? Figure out which of the two pins (1 and 3 in the plug) are getting a signal, cut the other one, and wire the good signal to both.

23485
 

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2005 Ranger XP 800
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30 and 31, the wire numbers, are also the pin numbers at the ECU, so the Green/White wire goes to pin 30 on the ECU and the Yellow/Brown wire goes to pin 31
 

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Discussion Starter #8
This is the ignition coil from my '08 RZR service manual (PM me your email and I can send it to you). The Red/Black is +12v from the EFI Power relay. The other two both go back to the ECU. From the schematic, it does send a separate signal from the ECU to the coils.

You might want to check the harness for those other two pins to see if they both make it back to your ECU. You might want to look at the wiring diagram for your bike, though I'm pretty sure 2010 is the same.

Another option? Figure out which of the two pins (1 and 3 in the plug) are getting a signal, cut the other one, and wire the good signal to both.

View attachment 23485
I have already considered your"other option". I'm pretty sure which side is getting signal, but will double check( pretty easy to do). I've recently gotten new info from a previous owner of this machine, and this isn't a new problem. I'll check the harness best I can, and if I find nothing... I'm gonna try the wire splice... thanks so much for the info...necessity is , in fact, the mother of invention...
 

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Discussion Starter #9
I have already considered your"other option". I'm pretty sure which side is getting signal, but will double check( pretty easy to do). I've recently gotten new info from a previous owner of this machine, and this isn't a new problem. I'll check the harness best I can, and if I find nothing... I'm gonna try the wire splice... thanks so much for the info...necessity is , in fact, the mother of invention...
Update... I back-fed power from the coil plug to the ECU plug, and found that there is continuity on both leads to the coil... so it's not the wiring harness, which is a plus, but indicates it is the ECU, which is bad...updates forthcoming..
 

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2005 Ranger XP 800
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If you were near, I'd just toss you one of my ECU spares to try swapping in...
 

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Discussion Starter #11
If you were near, I'd just toss you one of my ECU spares to try swapping in...
I've contacted a local electronics teacher I know about splitting the signal strength from the #1 coil lead( electrical theory not being my strong suit)...in the mean time I've liocated a used ECU for a "reasonable" price( at least relatively)... what's the chances it will be a functioning unit...?
 

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2005 Ranger XP 800
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I'd say it is a pretty good chance it is in good shape if the seller seems trustworthy.
I have a 2005 ranger, 2006 sportsman/rzr 800, and 2008 ranger ECU... so, all older than yours, and they all work like new.

As for taking the signal ground from the ECU and splitting it between both leads... in the absolute worst case, it could possibly, maybe, damage the #1 coil signal from the ECU. Since your ECU is otherwise junk, you kind of have nothing to lose ;)
 
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