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Hi. I'm hoping/looking for a response from Mike Mullen on this-

I have an 02 St4s that has the intermittent and unpredictable problem of firing for approx. 1/2 - 1-1/2 seconds then dying when attempting to start. This can be repeated at will by cycling the key off for a minimum of 30-45 seconds and re-cranking. The immobilizer light functions normally. At one point, I emailed one of the ECU repair facilities in the UK w/ a description of the symptoms. They replied they believed it was an immobilizer fault that they could reset for a healthy fee. My concern was if it was a fault reset, what would prevent it from recurring? I haven't been riding this year due to this and other projects, although there was a period of 2-3 months that the bike was starting and running normally w/ no problems.

Anyway, recently there was a 2003 ECU on Ebay, advertised as "new", p/n 28640751A (current p/n is 28640751B). I didn't have much time to research possible differences between 02 & 03, but the wiring schematics show identical pinouts, and the only other difference I'm aware of is the kickstand cutout change that allows the '03 to start in neutral on the kickstand.

So I received it today and installed it by first disconnecting the battery. Using a black key, the immobilizer light pulses for the normal (.7s), goes out for about 3 seconds, then comes back on steady. Fuel pump runs normally during this time, but upon cranking cylinders don't fire.

Mike, any help you could offer would be greatly appreciated. I am aware I have no insurance other than the sellers (good feedback w/ over 5500) claim, although I could see evidence of it having been installed by bright rings at the mounting lugs and the aluminum chassis has no signs of oxidation.

My preference would be not to program the red key, at least not until I determine whether the ECU is good and will run the bike.

Thanks,
Kevin Werner
 

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I thought that you had to program a new ECU with the red key so that the immobilizer would recognize it and allow the bike to start.

Maybe you should talk with a dealer about this, before you commit to locking the ECU to the bike.
 

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Life is too short to worry !
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I thought that you had to program a new ECU with the red key so that the immobilizer would recognize it and allow the bike to start.

Maybe you should talk with a dealer about this, before you commit to locking the ECU to the bike.
Thats what I understood to be the case but a dealer should be able to confirm/correct.
 

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I have this same problem that comes and goes. It happens at random times and if I let the bike sit it goes away and everything is fine. keep us updated with what you find out. good luck
 

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Hello
Well, I'm not Mr. Mullen, no matter what hotel I slept in last night, but...

I don't believe you ever have to introduce the red key if you don't want to. I also understand that the immobilizer light will continue to flash until you do, but I have never done so, therefore my lights flash all the time, so what do I know...
I also think that the fuel pump and ignition are on the same circuit, so if your fuel pump is priming, you should have power to your coils. Don't know if the immobilizer interupts the signal between the ECU and the coils, but I would suspect the signal would simply not be initiated at the ECU. That would also mean that you would not hear your fuel pump prime.
That's just a wild-ass guess. But, if it's even close, then maybe there is a problem elsewhere downstream of the ECU.
The '02/'03 ECU's should be totally interchangeable, with the '03 being a big reliability upgrade.

JMHO
 

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A truly new or virgin ECU will work on any bike without being red keyed. But, once red keyed it will never work on another bike with different key and dash panel. The odds are the unit you bought off ebay is not new and is allready mated to another bike. Sorry, I hope that's not the case but I've read this happens a lot on ebay.
 

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A truly new or virgin ECU will work on any bike without being red keyed. But, once red keyed it will never work on another bike with different key and dash panel.
Yup thats what I also understand. You have to get the whole kit once the ECU has been installed previously...I think its the ignition key unit with keys and ECU. the imobiliser thats mated to the ECU is in the ignition key unit and once the new ECU has been synchronised with this there is no going back:mad:
 

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When I first read it I thought maybe it was the kickstand but you say its intermittent. I know that mine is a 2003 and when I went to a DP ECU (2002 only) it changed to being a kickstand up only start.
 

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I'm not totally sure but I tend to agree with DuckMan. A friend had the same facts as you. 2002 ST4s with intermittant starting problems. He also bought an ECU off of Ebay (same story, it was virgin) with exactly the same results. We concluded that it was not a virgin ECU. Now it's a door stop. Don't have any technical data to back up the conclusion though. Just know it wouldn't fire. Tried the red key with no success.

Jeff
 

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Can these non-working "new" ECUs be reflashed by the kit Motowheels is selling, or does that not affect the immobilizer code?
 

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You should try this; if you have the capabilities to check error codes w/ the DDS or techno-research tool, clear the error codes and try starting. if it starts normally who knows how long before it acts up again, but when it does clear codes again and try again. If this is the case you need a new ECU (try this w/ your old ECU not the E-bay one)
I have seen 3 case's of this and I know it doesnt make any sense because in two of the case's the error codes where different, but each bike would start normally after clearing error codes. BTW in all 3 case's each bike would almost start, sometimes backfire then no start, cycle the key numerous times and bike would start for 2-3 seconds and die, let it sit overnight and would start for 5-10 seconds then die.
Installed a "test" ecu and all bikes started normally w/o any error codes popping up. After searching and inspecting the "error codes" and finding or replacing problem coils, engine rpm sensor or finding no problems each one responded by installing a new ECU. Just my .02
You should be able to use a new ecu or a "virgin" ecu w/o programing it w/ the red key and everything should work except for the imobolizer.
 

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fyi, 2003 st4s code will run on a 2002, that isn't the issue here. Others have described good options.

I definitely suggest vdsts to see what codes pop up as the best next step.
 
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