Things to Check on ST1300 for FI Light Code 26

Larry Fine said:
Robbie, to eliminate possibilities, can you swap sensors, or the sub-harnesses (if they match)?
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Yes, I realized that's the only thing on my original list that I didn't do. When I found the bad connector, I figured that had to be it. I'll swap them next time I have the plastics off and hope for the best.
 
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RobbieAG said:
I rode the bike to Ga-STOC last week and the FI light is back (code 26). I confirmed that my connection is still good and it's throwing the same code, so I have to conclude it's the ECM. I'll be on the lookout for a good used one if I can find one. There were no noticeable issues with riding the bike with the light on other than marginally reduced fuel economy. I'm disappointed, but it won't strand you so that's a plus.
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Larry reported seeing more Codes on bikes loaded with electrical accessories. How is yours on this front?

And some on the GL side seem to believe a noisy ground on the Knock Sensor Loop could be affecting the ECM on the GL and trigger their Knock Sensor Code, could be same for the ST. So cleaning/fastening grounds might help. They also suggest running a dedicated ground for this loop, but I have no idea how their scheme would translate to the ST.

Reading Dark Sun on the GL side, it sounds like a failed ECM is a failed ECM. But if it is only just about to fail, its life could be extended by cleaning and regrounding.

On a side note, a local shop I deal with just procured a ST ECM for a client, directly from somewhere in Japan, but keeping details for themselves.....Sounds like there may still be some available out there if you are lucky.
 
MidLife said:
Larry reported seeing more Codes on bikes loaded with electrical accessories. How is yours on this front?
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I have a power block under the seat and the quartet harness up front. Connected are heated grips, GPS connection and 12V connector up front. To the power block I have a heated gear connector and hyper lites connected. These have all been on the bike for years and never caused a problem. More recently I added TPMS, but this is wireless. I don't suppose that could cause a problem but it would be easy enough to remove to make sure.
 
RobbieAG said:
........ but it would be easy enough to remove to make sure.
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From what I gathered out of the GL posts linked to by Mellow, it is not an "on/off" situation.

More like the "dirtier (noisier)" the ground is (the more devices are going back to it), the faster the chip that talks/listens to the Knock Sensor in the ECM might give up.

Based on Larry's observations, it seems that loaded bikes are the ones more likely to get 26-ed first, possibly confirming the above.

He's been able to save some, by "cleaning" them up. But will only work if the ECM is not completely toast already.
 
Also remember that the more load you place on a ground wire, the more that voltage drop will lift it away from zero volts, just like it causes voltage to sag below +12v on a hot wire.

And, just as with a shared hot wire, a single ground wire shared among several loads will cause the effect to affect all of the loads, even if only one is causing most of the voltage drop.
 
Larry Fine said:
.......the more load you place on a ground wire, the more that voltage drop will lift it away from zero volts, .......
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That's why the GL guy recommends the Knock Loop be on a dedicated "cleaner" ground.

The knock sensing loop could probably be floated....but I wouldn't know where to start on that.
 
RobbieAG said:
I have a power block under the seat and the quartet harness up front. Connected are heated grips, GPS connection and 12V connector up front. To the power block I have a heated gear connector and hyper lites connected. These have all been on the bike for years and never caused a problem. More recently I added TPMS, but this is wireless. I don't suppose that could cause a problem but it would be easy enough to remove to make sure.
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Robbie - This makes my head hurt for you - problems that have 'intermittent' causes can drive a feller crazy after a while!
 
On the topic of find the cause of the problem instead of throwing parts at the situation I completely agree, but I can't help but remember getting to the end of my wits [and telephone book sized Honda factory service manual] when I was faced with the prospect of replacing the ECM in my 92 Accord at only 75,000km. After all the testing for an intermittent fault, the manual stated: "Substitute known good one" which at the time was $800.00 I called Honda and asked the parts guy how many of these things fail? He said not very many.
I got lucky after I think the third time removing the horizontally positioned distributor cap and found a small piece of porous metal laying inside. Turned out to be a failing distributor bearing resulting in one of the three rotors making contact with the pick-up coil. It wasn't skill, it wasn't expertise, it wasn't following the manual, it wasn't the process of elimination. That little piece could have just as easily dropped on the ground. Luck I tell you, sometimes you gotta have luck!
 
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