The real thing is that I need to know where the heck the knock sensor should connect. I removed the harness and now I don't know which one was the left and which one the right one, as I'm replacing the wires. Any help will be greatly painted with thankfulness.
Does anyone have the ECM Pinout for the ST1300 with ABS from 2003?
- Thread starter leondante
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I haven't got a clue - but I can read a circuit diagram.
My best guess is that the right sensor (Red/Blue wire) connects to pin 9 - top row, 9 pins from the left.
The Left sensor (blue wire) connects on pin 22 - immediately underneath pin 9.
But you should never rely on information from just once source - so here is my exaplanation as to why I come to this conclusion so that you can check it for yourself.
I have the printed Honda Service manual for UK ST100 A2 to A4. It contains the circuit digram for Spanish bikes as well as UK. This information is gleaned from that.
I checked it with USA circuit diagrams and they seem to be different.
The 2003 Spain diagram for the luxury (ABS) version shows the
BL wire going into pin 22 of the Grey connector.
The R/Bu wire going into pin 9
The fuel system testing part of the manual for FI error codes 25 and 26 indicate
that the Right knock sensor is the red/blue wire
the left knock senosr is the blue wire.
So I guess that someone made a mistake in the circuit diagram and labelled the Blue wire as 'Bl' when it should be 'Bu'
But there is no doubt that the wire labelled Bl comes from the knock sensor (Except the circuit diagram doesn't lable the side of the knock sensor.
The text of the testing section in the manual shows the 26 pin connectors and labels them from left to right - top row pins 1 to 13, bottom row pins 14 to 26
So Pin 9 is directly above pin 22.
There is the opportunity for these pins to be looked at upside down or from the point of view of the mating connector. So to be sure, there are two vertical mouldings between the top row and the bottom row so that they cannot be plugged together the wrong way round.
One moulding is on the left between pins 1/2 and 14/15
the other is roughly central between pins 6/7 and 19/20
You can see these in the poor quality images that I pinched from an on-line manual. My printed one which shows the same diagrams is much clearer.
So pins 9 and 22 are the thrid pins to the right of the central moulding.
But there are rumours around that the manual has the fault codes 25 and 26 the wrong way round anyway. So I guess it doesn't matter which is left and which is right !!
The diagram below is from the manual to show the test harness. I have made a big assumption that the grey connector is the one that I have labelled - because elsewhere I read that the knock sensor pins are in the grey connector and that connector is shown on the right in the circuit diagram.
I repeat - I do not know any of this - I have the 2003 UK and Europe manual so I have tried to work out what goes where from that. The circuit diagram for Spain is the same as the diagram for UK as far as the knock sensors and the ECMs are concerned - but they appear to be different from the circuit diagrams that are published on this site.
This is all that I can find - check it through to see if it makes sense according to the wiring that you have in your hand. If any of it doesn't match, then everything that I have written is probably incorrect.
My best guess is that the right sensor (Red/Blue wire) connects to pin 9 - top row, 9 pins from the left.
The Left sensor (blue wire) connects on pin 22 - immediately underneath pin 9.
But you should never rely on information from just once source - so here is my exaplanation as to why I come to this conclusion so that you can check it for yourself.
I have the printed Honda Service manual for UK ST100 A2 to A4. It contains the circuit digram for Spanish bikes as well as UK. This information is gleaned from that.
I checked it with USA circuit diagrams and they seem to be different.
The 2003 Spain diagram for the luxury (ABS) version shows the
BL wire going into pin 22 of the Grey connector.
The R/Bu wire going into pin 9
The fuel system testing part of the manual for FI error codes 25 and 26 indicate
that the Right knock sensor is the red/blue wire
the left knock senosr is the blue wire.
So I guess that someone made a mistake in the circuit diagram and labelled the Blue wire as 'Bl' when it should be 'Bu'
But there is no doubt that the wire labelled Bl comes from the knock sensor (Except the circuit diagram doesn't lable the side of the knock sensor.
The text of the testing section in the manual shows the 26 pin connectors and labels them from left to right - top row pins 1 to 13, bottom row pins 14 to 26
So Pin 9 is directly above pin 22.
There is the opportunity for these pins to be looked at upside down or from the point of view of the mating connector. So to be sure, there are two vertical mouldings between the top row and the bottom row so that they cannot be plugged together the wrong way round.
One moulding is on the left between pins 1/2 and 14/15
the other is roughly central between pins 6/7 and 19/20
You can see these in the poor quality images that I pinched from an on-line manual. My printed one which shows the same diagrams is much clearer.
So pins 9 and 22 are the thrid pins to the right of the central moulding.
But there are rumours around that the manual has the fault codes 25 and 26 the wrong way round anyway. So I guess it doesn't matter which is left and which is right !!
The diagram below is from the manual to show the test harness. I have made a big assumption that the grey connector is the one that I have labelled - because elsewhere I read that the knock sensor pins are in the grey connector and that connector is shown on the right in the circuit diagram.
I repeat - I do not know any of this - I have the 2003 UK and Europe manual so I have tried to work out what goes where from that. The circuit diagram for Spain is the same as the diagram for UK as far as the knock sensors and the ECMs are concerned - but they appear to be different from the circuit diagrams that are published on this site.
This is all that I can find - check it through to see if it makes sense according to the wiring that you have in your hand. If any of it doesn't match, then everything that I have written is probably incorrect.
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What would be the consequences of a mix-up (besides getting a MIL 25 when it should have been 26)?
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I don't know. I'm not offering anything here other than reading the information that I have available to me and posting what I have found out.
But I can speculate. If an engine is knocking then I believe that it can be due to...
Overheating, too weak a mixture (too much air, too little fuel), low octane fuel, ignition too far advanced, carbon build up in cylinder head, engine load.
My knowledge is limited and based on experience with a BSA bantam where no automatic advance /retard was available. Too far advanced it would knock like crazy. Not enough and it was almost impossible to accelerate. Too much fuel and the exhaust would be smokey and the plugs black, too little and the engine would get hot, it would knock, and plugs would be white. Knocking is a poor word - I like the term 'pink' as that is what it sounds like when said in a high pitched voice - like a bunch of keys rattling in a metal tin.
I cannot think of any thing that the engine management system can do to compensate for knocking on just one one side of the engine. If that is the case, then all the ECM is interested in is whether the engine is knocking and not which cylinder is knocking. It can then adjust advance/retard or alter fuel mixture for all cylinders to keep the engine balanced - or use a pre-determined mapping.
Note I ASSUME that the diagram shows the sockets for the cable that plugs into the ECM - not the pins on ECM itself which will be a mirror image - but that assumption may be wrong.
edit - Yes - that assumption was wrong. I found the details of the test harness. The diagram shown is of the test harness and the pin positions correspond to the pins on the ECU itself.
The two mouldings prevent the cable from being inserted upside down, Make sure by comparing the position of the mouldings on the ECM and on the connector that plugs into it - as wella s with the diagram. If necessary use the colours of the other wires to make sure you have the correct orientation.
Looking at very unclear photos on-line, I think the location mouldings may be on the outside of the harness connector body and inside the casing on the ECU
I haven't seen a connector to know how that looks - and I cannot find one that shows the pins head on . If @leondante can post photos of the ECM and the connector it would give us a better idea. It would be particularly useful to know colours of any other wires that are still connected and their positions so I can relate those to the diagrams above. I'll get some better scans from the circuit diagram that I have.
I no longer have my earlier model ST1300 - mine is an A9 which has a different ECM.
But I can speculate. If an engine is knocking then I believe that it can be due to...
Overheating, too weak a mixture (too much air, too little fuel), low octane fuel, ignition too far advanced, carbon build up in cylinder head, engine load.
My knowledge is limited and based on experience with a BSA bantam where no automatic advance /retard was available. Too far advanced it would knock like crazy. Not enough and it was almost impossible to accelerate. Too much fuel and the exhaust would be smokey and the plugs black, too little and the engine would get hot, it would knock, and plugs would be white. Knocking is a poor word - I like the term 'pink' as that is what it sounds like when said in a high pitched voice - like a bunch of keys rattling in a metal tin.
I cannot think of any thing that the engine management system can do to compensate for knocking on just one one side of the engine. If that is the case, then all the ECM is interested in is whether the engine is knocking and not which cylinder is knocking. It can then adjust advance/retard or alter fuel mixture for all cylinders to keep the engine balanced - or use a pre-determined mapping.
Note I ASSUME that the diagram shows the sockets for the cable that plugs into the ECM - not the pins on ECM itself which will be a mirror image - but that assumption may be wrong.
edit - Yes - that assumption was wrong. I found the details of the test harness. The diagram shown is of the test harness and the pin positions correspond to the pins on the ECU itself.
The two mouldings prevent the cable from being inserted upside down, Make sure by comparing the position of the mouldings on the ECM and on the connector that plugs into it - as wella s with the diagram. If necessary use the colours of the other wires to make sure you have the correct orientation.
Looking at very unclear photos on-line, I think the location mouldings may be on the outside of the harness connector body and inside the casing on the ECU
I haven't seen a connector to know how that looks - and I cannot find one that shows the pins head on . If @leondante can post photos of the ECM and the connector it would give us a better idea. It would be particularly useful to know colours of any other wires that are still connected and their positions so I can relate those to the diagrams above. I'll get some better scans from the circuit diagram that I have.
I no longer have my earlier model ST1300 - mine is an A9 which has a different ECM.
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Most likely.
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Final addition - the Spanish version of the Circuit diagram for ST1300 A2/3/4 - with the red/blue wires coloured in red
and the 'Bl' wired coloured in blue.
and the 'Bl' wired coloured in blue.
Guys, that was amazing. Long time none did such helpful stuff for me.
I'm taking pictures and posting them later of the ECM and the plugs. Mine are so toasted that colors don't match the wiring diagram. Or for some reason those are other color than the diagram.
I'm thinking, cannot just one cylinder of the engine knock and be that the reason why it has one at each side and not one in the center of the engine, to change settings just in one half of the engine and not all of it? Cannot be just one side of the engine controlled so the power losing affects half the cylinders and not all of them? If just one cylinder is having too much or too poor mixture is worse to change all the cylinders instead of just that one (or half of them, as it could be in this case). I don't know so I'm asking, as I'm not that familiar with the ECM working stuff.
I'm taking pictures and posting them later of the ECM and the plugs. Mine are so toasted that colors don't match the wiring diagram. Or for some reason those are other color than the diagram.
I'm thinking, cannot just one cylinder of the engine knock and be that the reason why it has one at each side and not one in the center of the engine, to change settings just in one half of the engine and not all of it? Cannot be just one side of the engine controlled so the power losing affects half the cylinders and not all of them? If just one cylinder is having too much or too poor mixture is worse to change all the cylinders instead of just that one (or half of them, as it could be in this case). I don't know so I'm asking, as I'm not that familiar with the ECM working stuff.
Why is that? It cannot be only one cylinder, as it is multi-point injection? Cannot manage independently each injector?
ECM is not that advanced. Newer vehicles would have a code for cylinder imbalance but it still can't determine which cylinder.
No way to adjust only one of the four cylinders as there are only two sensors. At the most it would be the left or the right bank.
But most important, as stated by Professor @jfheath earlier.....
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I think that the only reason it has two knock sensors and not one is because the knocking takes place in the cylinder and one pair is quite distant from the other pair in that Vee configuration. The sensor is positioned under the exhaust port of one of the cyclinders.
I forgot to check that one - you have to be careful - there are subtle differences in the wiring schematics. Mostly they are the same - but since I had the manual for exactly your model, I thought that I would copy that. The coloured one that you have posted is from @SpikingJC is one that I use quite a lot - and it matches with mine in the wiring for the ECM. Some don't. It also has the wiring for the passing switch - which is absent on the USA models.
Dont forget that the diagrams show the left hand sensor with a 'Bl' wire - which is black. The text in the service manual says 'Blue'. One of them is probably correct. One is definitely wrong.
The diagrams have gone with black. I went with the colour that is in the text of the manual - so that the error could be spotted whichever one you read !
Edit. That wire is definitely black when it leaves the connector - see the photos below.
Here is the text in the manual that refers to the lead for the right sensor being blue.
And that is a lesson to be learned. The manual has a lot of errors in it. A handful of them are VERY serious. Generally on the labeling of diagrams, but having said that I have come across a few errors on the circuit diagrams. Fortunately there are text, tables, diagrams, check lists that contain the same information in different locations. So when you read something - check it against the spec tables in chapter one, the general information at the start of each chapter, the labeled diagrams, the text in bold alongside diagram and the feinter side notes. And your common sense.
If you don't have the service manual - google is your friend. But there is nothing like having a printed copy.
I forgot to check that one - you have to be careful - there are subtle differences in the wiring schematics. Mostly they are the same - but since I had the manual for exactly your model, I thought that I would copy that. The coloured one that you have posted is from @SpikingJC is one that I use quite a lot - and it matches with mine in the wiring for the ECM. Some don't. It also has the wiring for the passing switch - which is absent on the USA models.
Dont forget that the diagrams show the left hand sensor with a 'Bl' wire - which is black. The text in the service manual says 'Blue'. One of them is probably correct. One is definitely wrong.
The diagrams have gone with black. I went with the colour that is in the text of the manual - so that the error could be spotted whichever one you read !
Edit. That wire is definitely black when it leaves the connector - see the photos below.
Here is the text in the manual that refers to the lead for the right sensor being blue.
And that is a lesson to be learned. The manual has a lot of errors in it. A handful of them are VERY serious. Generally on the labeling of diagrams, but having said that I have come across a few errors on the circuit diagrams. Fortunately there are text, tables, diagrams, check lists that contain the same information in different locations. So when you read something - check it against the spec tables in chapter one, the general information at the start of each chapter, the labeled diagrams, the text in bold alongside diagram and the feinter side notes. And your common sense.
If you don't have the service manual - google is your friend. But there is nothing like having a printed copy.
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I didn't took the connectors out because I think it seems good this way, anyways if you want them out I can do it. But from the front you'll have not the colors to know where is each one. Ley me know if you or anyone wants more pictures, I'm gladly taking them. Sorry for being a bit late with them.
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@leondante - many thanks for posting these pictures of the connectors. That has enabled me to confirm how the physical connectore relate to the circuit diagram in the manual - and to finally answer the question about the pin-outs for the knock sensors. I think my assumption above was correct - but I've reproduced the relevant bit of the Honda Circuit diagram and the relavant cropped image from your photos.
Goodness me - those wires and connectors are clean for a 22 year old bike !!!! Oh and the dilemma about the diagram calling the wire Black and the text in the manual calling it Blue is now resolved. The Sensor Wire is black. The circuit diagram is correct, the text in the manual (blue) is wrong.
These two images confirm the layout. Ive coloured a light grey block on the left (= back row in the top photo) and a white block on the right (= front row in the top photo)
The two sensor pins are shown with a black rectangular block (left sensor?) and a red/blue rectangular block (right sensor?)
The circuit diagram - as it relates to your photo:
The right hand 13 wires in the circuit diagram are identical to the 13 pins at the front of your photo - which is the first photo reproduced below.
Reading the diagram from right to left and the front row of the photo from right to left:
diag = photo
---------------
Gr = Grey wire
Bl/O - Black/Orange wire
G/R = Green / Red wire
Gap = no wire
Bl = Black - **** this is the wire that connects to one of the sensors.
G = Green wire
Gap = no wire
Lg = Light green wire
Gap = no wire
Gap = no wire
P/G = Pink / Green wire
G/O = Green / Orange wire
W/Y = White/Yellow Wire
The back row of wires in the photo also match the diagram - from the right hand side of the photo
and continuing with the Y wire in the middle of the circuit diagram
Y = Yellow wire, back row right hand side of photo
Bl/R = Black / Red wire
G/W = Green/ White wire
Gap = no wire
R/Bu = Red Blue wire ****** This is the other knock sensor wire
P = Pink wire
Gr/Bu = Grey Blue wire (looks just grey)
Y/Bu = Yelllow / Blue wire -
Lg/W = Light Green / White wire
Gap = No wire
Br = Brown Wire
Gap = no wire
Bl/W =Black/White wire
The wires at the rear of the white block become obscured but can be seen more clearly looking at this photo. Often the second colour is difficult to see.
So for the white connector, the wires in the diagram that I obtained from my ST1300A3 manual - Spanish page match exaclty the wires in your photo.
So the pins for the Knock Sensor are the 5th from the right in your top photo - both rows. Note the comment I made in an earlier post.
The circuit diagram doesn't identify left and right sensor. One wire is black, one wire is red/blue. The text in the manual identifies the left sensor as the one with the Blue Wire - which I believe is an error. It should say Black wire. Someone may have mistaken Bl to mean Blue. Bl is black. Bu is blue.
The sensor wire is Bl = black. The code for a blue wire is Bu.
Note that for the white connector at least - my circuit diagram matches your coloured wires EXACTLY. The coloured one that you posted isn't quite the same (A pink an green and a black wire are missing from the coloured diagram. But the Black and Red/Blue wires for the knock sensors are in the same position.
For the sake of providing the full picture - I compared the wires in your photos of the black connector to the ones in the 2003A circuit diagram from the Honda manual.
They are a perfect match as well - and exactly the same diagram is used fro the En/French/German version - its just that the text is in different languages on the spanish version.
This is the 2003/ model.
The 2004 version has a couple of colour differences. Maybe error corrections ?
In the black connector right hand end the G/P G/P Y/R G/P are labelled as G/P G/Bu Y/R G/O on the 2004 diagram - which more closely matches the colours of your wires.
I must admit that I was having trouble making that G/O wire look green and purple.
Goodness me - those wires and connectors are clean for a 22 year old bike !!!! Oh and the dilemma about the diagram calling the wire Black and the text in the manual calling it Blue is now resolved. The Sensor Wire is black. The circuit diagram is correct, the text in the manual (blue) is wrong.
These two images confirm the layout. Ive coloured a light grey block on the left (= back row in the top photo) and a white block on the right (= front row in the top photo)
The two sensor pins are shown with a black rectangular block (left sensor?) and a red/blue rectangular block (right sensor?)
The circuit diagram - as it relates to your photo:
The right hand 13 wires in the circuit diagram are identical to the 13 pins at the front of your photo - which is the first photo reproduced below.
Reading the diagram from right to left and the front row of the photo from right to left:
diag = photo
---------------
Gr = Grey wire
Bl/O - Black/Orange wire
G/R = Green / Red wire
Gap = no wire
Bl = Black - **** this is the wire that connects to one of the sensors.
G = Green wire
Gap = no wire
Lg = Light green wire
Gap = no wire
Gap = no wire
P/G = Pink / Green wire
G/O = Green / Orange wire
W/Y = White/Yellow Wire
The back row of wires in the photo also match the diagram - from the right hand side of the photo
and continuing with the Y wire in the middle of the circuit diagram
Y = Yellow wire, back row right hand side of photo
Bl/R = Black / Red wire
G/W = Green/ White wire
Gap = no wire
R/Bu = Red Blue wire ****** This is the other knock sensor wire
P = Pink wire
Gr/Bu = Grey Blue wire (looks just grey)
Y/Bu = Yelllow / Blue wire -
Lg/W = Light Green / White wire
Gap = No wire
Br = Brown Wire
Gap = no wire
Bl/W =Black/White wire
The wires at the rear of the white block become obscured but can be seen more clearly looking at this photo. Often the second colour is difficult to see.
So for the white connector, the wires in the diagram that I obtained from my ST1300A3 manual - Spanish page match exaclty the wires in your photo.
So the pins for the Knock Sensor are the 5th from the right in your top photo - both rows. Note the comment I made in an earlier post.
The circuit diagram doesn't identify left and right sensor. One wire is black, one wire is red/blue. The text in the manual identifies the left sensor as the one with the Blue Wire - which I believe is an error. It should say Black wire. Someone may have mistaken Bl to mean Blue. Bl is black. Bu is blue.
The sensor wire is Bl = black. The code for a blue wire is Bu.
Note that for the white connector at least - my circuit diagram matches your coloured wires EXACTLY. The coloured one that you posted isn't quite the same (A pink an green and a black wire are missing from the coloured diagram. But the Black and Red/Blue wires for the knock sensors are in the same position.
For the sake of providing the full picture - I compared the wires in your photos of the black connector to the ones in the 2003A circuit diagram from the Honda manual.
They are a perfect match as well - and exactly the same diagram is used fro the En/French/German version - its just that the text is in different languages on the spanish version.
This is the 2003/ model.
The 2004 version has a couple of colour differences. Maybe error corrections ?
In the black connector right hand end the G/P G/P Y/R G/P are labelled as G/P G/Bu Y/R G/O on the 2004 diagram - which more closely matches the colours of your wires.
I must admit that I was having trouble making that G/O wire look green and purple.
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These two images confirm the layout. Ive coloured a light grey block on the left (= back row in the top photo) and a white block on the right (= front row in the top photo)
The two sensor pins are shown with a black rectangular block (left sensor?) and a red/blue rectangular block (right sensor?)
The circuit diagram - as it relates to your photo:
The right hand 13 wires in the circuit diagram are identical to the 13 pins at the front of your photo - which is the first photo reproduced below.
Reading the diagram from right to left and the front row of the photo from right to left:
diag = photo
---------------
Gr = Grey wire
Bl/O - Black/Orange wire
G/R = Green / Red wire
Gap = no wire
Bl = Black - **** this is the wire that connects to one of the sensors.
G = Green wire
Gap = no wire
Lg = Light green wire
Gap = no wire
Gap = no wire
P/G = Pink / Green wire
G/O = Green / Orange wire
W/Y = White/Yellow Wire
The back row of wires in the photo also match the diagram - from the right hand side of the photo
and continuing with the Y wire in the middle of the circuit diagram
Y = Yellow wire, back row right hand side of photo
Bl/R = Black / Red wire
G/W = Green/ White wire
Gap = no wire
R/Bu = Red Blue wire ****** This is the other knock sensor wire
P = Pink wire
Gr/Bu = Grey Blue wire (looks just grey)
Y/Bu = Yelllow / Blue wire -
Lg/W = Light Green / White wire
Gap = No wire
Br = Brown Wire
Gap = no wire
Bl/W =Black/White wire
The wires at the rear of the white block become obscured but can be seen more clearly looking at this photo. Often the second colour is difficult to see.
So for the white connector, the wires in the diagram that I obtained from my ST1300A3 manual - Spanish page match exaclty the wires in your photo.
So the pins for the Knock Sensor are the 5th from the right in your top photo - both rows. Note the comment I made in an earlier post.
The circuit diagram doesn't identify left and right sensor. One wire is black, one wire is red/blue. The text in the manual identifies the left sensor as the one with the Blue Wire - which I believe is an error. It should say Black wire. Someone may have mistaken Bl to mean Blue. Bl is black. Bu is blue.
The sensor wire is Bl = black. The code for a blue wire is Bu.
Note that for the white connector at least - my circuit diagram matches your coloured wires EXACTLY. The coloured one that you posted isn't quite the same (A pink an green and a black wire are missing from the coloured diagram. But the Black and Red/Blue wires for the knock sensors are in the same position.
For the sake of providing the full picture - I compared the wires in your photos of the black connector to the ones in the 2003A circuit diagram from the Honda manual.
They are a perfect match as well - and exactly the same diagram is used fro the En/French/German version - its just that the text is in different languages on the spanish version.
This is the 2003/ model.
The 2004 version has a couple of colour differences. Maybe error corrections ?
In the black connector right hand end the G/P G/P Y/R G/P are labelled as G/P G/Bu Y/R G/O on the 2004 diagram - which more closely matches the colours of your wires.
I must admit that I was having trouble making that G/O wire look green and purple.
Beautiful explanation, thank you very much.
