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.
Last edited:
What would be the consequences of a mix-up (besides getting a MIL 25 when it should have been 26)?
- Joined
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- 002293
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.
Last edited:
Most likely.
- Joined
- Mar 18, 2006
- Messages
- 3,175
- Location
- Ilkley, W Yorkshire, UK
- Bike
- 2013 ST1300 A9
- 2025 Miles
- 002293
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.....
- Joined
- Mar 18, 2006
- Messages
- 3,175
- Location
- Ilkley, W Yorkshire, UK
- Bike
- 2013 ST1300 A9
- 2025 Miles
- 002293
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 !
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 !
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.