ST1300 ECU-Knock sensor problem

I have recently purchased a ST1300 privately and unfortunately I have inherited the dreaded fault 26 problem.

On investigation I have found the wiring harness has already been repaired and that the fault is with the ECU.
I've checked the inputs at the ECU with an oscilloscope and done the usual tests to prove the knock sensors and wiring are OK.

]So.. a cheap repair is not on the table and I have the following options….

New ECU..about £1500 by the time you have paid VAT and fitting. A lot of money to spend on an 04 bike that you have just bought!

Second-hand ECU £400ish but this is a bit tricky as you need the keys as well, or at the very least the transponder chips. A lot cheaper but they seem very rare, none on Ebay for the last week or so.

Anyone on here with one for sale?

American ECU without HISS?? Some other Honda forums (models) show how you can use an American non HISS ECU but you need to supply 9v to the one of the unused pins, this varies from bike to bike.

Has anyone on this forum got any ideas on the pins that might need this supply? There are plenty of non Hiss American ECUs available and I am familiar on how to use a zenor diode to create the 9v, so this route seems attractive if[/FONT][FONT=&quot] I know it's going to work.

The seller has point blank refused to help with the issue, I'd paid for the bike before I saw the fault (only appears above 4000rpm for over 10 seconds).

Thanks for any advice.

Shaw

Same bike, no HISS, same problem here, so I will be following this post too. I hadn't heard of this 9v thing, where did you? Thanks, Dave

Shaw said:

American ECU without HISS?? Some other Honda forums (models) show how you can use an American non HISS ECU but you need to supply 9v to the one of the unused pins, this varies from bike to bike.

Has anyone on this forum got any ideas on the pins that might need this supply

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Shouldn't be hard to run down. The wiring diagram for North American bikes shows a Black/White line coming from the bank angle relay that switches power to the things needed to run the engine: ignition coils, fuel injectors, oxygen sensors, air injection solenoid and the ECM. That circuit splits at the ECM and enters on two of the pins, but none of the diagrams show which pins they are. If you could tell us which connector and pin has that wire on your bike, somebody with a North American bike or just a spare harness could tell you where the other one goes.

I hadn't heard the 9V angle, and North American wiring doesn't seem to support it. There's nothing outside the ECM that can supply anything but 12V, so unless they've started doing that on other bikes, it doesn't apply to the ST.

--Mark

Blrfl said:

Shouldn't be hard to run down. The wiring diagram for North American bikes shows a Black/White line coming from the bank angle relay that switches power to the things needed to run the engine: ignition coils, fuel injectors, oxygen sensors, air injection solenoid and the ECM. That circuit splits at the ECM and enters on two of the pins, but none of the diagrams show which pins they are. If you could tell us which connector and pin has that wire on your bike, somebody with a North American bike or just a spare harness could tell you where the other one goes.

I hadn't heard the 9V angle, and North American wiring doesn't seem to support it. There's nothing outside the ECM that can supply anything but 12V, so unless they've started doing that on other bikes, it doesn't apply to the ST.

--Mark

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OK, thanks for that I'll do some tracing.

The 9V thing came from this video
https://www.youtube.com/watch?v=unqt7Eqj-tA

This other video contradicts the 9V advice and uses battery voltage.
https://www.youtube.com/watch?v=Cjqz-vOC-MY

I've now sourced an European ECU with keys but it's a bit pricey so i haven't written off the American ECU approach just yet.

Shaw

So what's the harm/foul if you just ignore the code and ride it? I assume it might retard the ignition timing some but it might still run well...just curious, and it's the cheapest solution......ff

flyfisher said:

So what's the harm/foul if you just ignore the code and ride it? I assume it might retard the ignition timing some but it might still run well...just curious, and it's the cheapest solution......ff

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Part of it is fuel mileage and performance, other part is if ignoring F1 light what other warnings are we ignoring that that light may be trying to tell us.

[FONT=&amp]Quote "New ECU..about £1500 by the time you have paid VAT and fitting"

how much is the part only ? Installation is an easy DIY job.
[/FONT]

flyfisher said:

So what's the harm/foul if you just ignore the code and ride it?

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This image search should answer that question.

--Mark

v8-7 said:

[FONT=&amp]Quote "New ECU..about £1500 by the time you have paid VAT and fitting"

how much is the part only ? Installation is an easy DIY job.
[/FONT]

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Part is £1400, it's worth the £100 installation so if there is a problem you have more protection.

Blrfl said:

This image search should answer that question.

--Mark

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Ouch!

Shaw

Shaw said:

Part is £1400, it's worth the £100 installation so if there is a problem you have more protection.

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A hundred quid to remove the pillion seat and the rubber retainer that holds the old ECM in place, disconnect two connectors, reconnect them to the new ECM, install the rubber retainer and put the seat back on just seems a little... stiff. It's ten minutes' work if you're slow about it.

--Mark

I understand the damage uncontrolled knock can cause in an engine, but a failed sensor (one side) I wouldn't think would actually CAUSE knock....and the other sensor presumably still works, and I'm also assuming that the timing controlled by the one good sensor should prevent knocking....as far as being able to read multiple warnings from the FI light I believe the ECU can store multiple codes.....still wondering if saving 1500 bucks would be an option....educate me.........ff

Oscilloscope readings of both knock sensors at 4000rpm, I'm assuming that them both being identical is telling me that the knock sensors are OK.

flyfisher said:

I understand the damage uncontrolled knock can cause in an engine, but a failed sensor (one side) I wouldn't think would actually CAUSE knock....and the other sensor presumably still works, and I'm also assuming that the timing controlled by the one good sensor should prevent knocking....as far as being able to read multiple warnings from the FI light I believe the ECU can store multiple codes.....still wondering if saving 1500 bucks would be an option....educate me.........ff

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Short answer is the sensor changes the timing, dose not cause knocking of course. But that is not healthy either. ECU dose hold many codes but why keep checking all the time, when it's more likely that people will just get frustrated that the light is on all the time and ignore it or even cover it up as in what I might do.

Any one in So Cal have a oscilloscope?

flyfisher said:

I understand the damage uncontrolled knock can cause in an engine, but a failed sensor (one side) I wouldn't think would actually CAUSE knock....and the other sensor presumably still works, and I'm also assuming that the timing controlled by the one good sensor should prevent knocking....as far as being able to read multiple warnings from the FI light I believe the ECU can store multiple codes.....still wondering if saving 1500 bucks would be an option....educate me.........ff

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I can't say one way or the other, I just don't feel comfortable going on a 2000 mile trip with a fault on the ECU. There is the big question mark on whether the timing is retarded by the fault, other threads on here indicate that it is and fuel economy is affected.

Shaw

I understand, do what you're comfortable with....don't know your financial situation or what you paid for the bike....if it was MINE I'd ride it a bit and see how it runs, fuel economy etc....good luck, enjoy the bike....ff

Shaw said:

Oscilloscope readings of both knock sensors at 4000rpm, I'm assuming that them both being identical is telling me that the knock sensors are OK.

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In my business, we call this "bringing the right tools to diagnose a problem." Well done. If those were taken at the ECM, your sensors and the wiring are fine.

Shaw said:

I can't say one way or the other, I just don't feel comfortable going on a 2000 mile trip with a fault on the ECU. There is the big question mark on whether the timing is retarded by the fault, other threads on here indicate that it is and fuel economy is affected.

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I'd have to assume that if one of the knock sensors is confirmed dead, the fallback would be to retard the timing on that side of the engine to avoid damage. That's how I'd build it, anyway. I don't know of any harmful side effects of running retarded over the long term other than off-nominal performance and fuel economy, so it's probably safe to ride the bike with a dead sensor. (That advice is worth exactly what you paid me for it; make your own decision.)

--Mark

Blrfl said:

A hundred quid to remove the pillion seat and the rubber retainer that holds the old ECM in place, disconnect two connectors, reconnect them to the new ECM, install the rubber retainer and put the seat back on just seems a little... stiff. It's ten minutes' work if you're slow about it.

--Mark

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I don't know about your ST, but on my 2003, the ECm can't be accessed from under the seat. I would have to disassemble at least part of the tail section to get to the ECM. I haven't done that yet, but a couple of sources advise me of that procedure, including the Honda SM.

BTW, I have a ST1300A, so the under-seat access is to the ABS module.

Blrfl said:

A hundred quid to remove the pillion seat and the rubber retainer that holds the old ECM in place, disconnect two connectors, reconnect them to the new ECM, install the rubber retainer and put the seat back on just seems a little... stiff. It's ten minutes' work if you're slow about it.

--Mark

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The 100 quid part was a guess by me but don't forget in the UK you have to deal with the HISS. I think the new ECM comes with new transponders which have to be put into your old keys.