Cured>>2009 ST1300 wont start no ignition.

CruSTy

CruSTy

My Perception is my reality.
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Joined
Jun 30, 2013
Messages
502
Age
72
Location
Paola, Kansas
Bike
2007 ST1300A
This is my response to a thread started by a rider with a no start condition 2 Honda dealers were unable to resolve. I am posting a new thread to save some reading in case someone else runs into this issue. After studying the ST1300 wiring diagrams till my eyes crossed I was able to isolate the issue to a single circuit that supplies power to the ECM, Fuel pump relay, ignition coils and most of the FI sensors on the bike. The ECM would not energize and would not go into daig mode when the test connector was jumped. Would not indicate any codes either. That Circuit (Black with White stripe wires) is energized from the Bank angle relay. Leaving the Bank angle relay the BL/W wire enters the wiring harness and somewhere within the harness it is tapped and splits into several directions. Every where after entering the harness there was no or insufficient voltage (less than 3v) to power anything. Two of the taps lead back out of the harness to the Fuel pump relay which was mounted next to the Bank angle relay. As a test I fabricated a jumper to jump from the BL/W at the Bank angle relay (12+v) to the BL/W at the Fuel pump relay. This energized the circuit fully and the bike was operational. At that point I concluded that there was a break in the BL/W wire within the harness. Short of ripping the harness apart to find the break we opted to leave that jumper in place. I found no signs of rodent damage or pinched harness or evidence of previous repairs. Should the broken wires suddenly heal them selves they would only act as a redundant connection to my jumper fix. Someone with experience opening an ST1300 wiring harness may have more input on this. If anyone knows where the junction is within the harness would be interested in knowing. The rider and I rode for about 100 miles today with no codes and no issues. I am adding a link to the original thread if you are interested in reading. I enjoyed the challenge and got to meet a fellow ST rider and he is back on the road.

Original Post

Chuck
 
Not noted on the schematics, there is a yellow +positive buss connector wrapped on top of the wire loom in front of the lower gas tank. It’s a pain to get to but it is accessible and may be where the problem lies if not in the harness itself. I like your jumper solution but as you can see in the photo of my connector, if that’s where the problem originated further investigation may be required down the line if indeed that was the cause. As a side note and also not on the schematic, there is also a pink -negative buss connector wrapped on the underside of the loom there. And hats off to you for helping the bikes owner and finding/repairing the problem in a timely mater, it took me much longer.
2624384A-1C0E-4263-8BE6-88A4EF36C827.jpeg
 
playfair said:
Great diagnosing job! It's nice you had "fun" with the challenge; the only satisfying time is once it's figured out, before that very irritating!
I recently found a short where the main harness passes under the seat to the fuse/relay center, perhaps that's a spot you should check?
https://www.st-owners.com/forums/index.php?threads/no-headlamps.165231/page-4
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I expect the break is close to that area but at this point not worth the effort to dissect the harness to see. Thanks for your comment.
 
Trapperdog said:
Not noted on the schematics, there is a yellow +positive buss connector wrapped on top of the wire loom in front of the lower gas tank. It’s a pain to get to but it is accessible and may be where the problem lies if not in the harness itself. I like your jumper solution but as you can see in the photo of my connector, if that’s where the problem originated further investigation may be required down the line if indeed that was the cause. As a side note and also not on the schematic, there is also a pink -negative buss connector wrapped on the underside of the loom there. And hats off to you for helping the bikes owner and finding/repairing the problem in a timely mater, it took me much longer.
2624384A-1C0E-4263-8BE6-88A4EF36C827.jpeg
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You certainly had some unpleasant surprises there. Would you have a pic showing the color code of the wires in that connector?
 
As I recall they were all Bl/w wires, 2 or 3 different gauges though. I have a used harness that I picked up for parts that I can check though
 
Awesome Chuck! Kudos for sticking with the problem bike/owner and helping him through it. I'll keep updating my thread as I find out more and hopefully will end up with the same result!
 
Trapperdog said:
Not noted on the schematics, there is a yellow +positive buss connector wrapped on top of the wire loom in front of the lower gas tank. It’s a pain to get to but it is accessible and may be where the problem lies if not in the harness itself. I like your jumper solution but as you can see in the photo of my connector, if that’s where the problem originated further investigation may be required down the line if indeed that was the cause. As a side note and also not on the schematic, there is also a pink -negative buss connector wrapped on the underside of the loom there. And hats off to you for helping the bikes owner and finding/repairing the problem in a timely mater, it took me much longer.
2624384A-1C0E-4263-8BE6-88A4EF36C827.jpeg
Click to expand...
You said this connector is not mentioned on the wiring diagram. I looked at the parts fische and don't see it there either. Do you know if it is documented anywhere in the manual or parts fische?
 
CruSTy said:
You said this connector is not mentioned on the wiring diagram. I looked at the parts fische and don't see it there either. Do you know if it is documented anywhere in the manual or parts fische?
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I do not believe so as I couldn’t find it either. When diagnosing my ‘09 1300P with the same issue, I happened on it accidentally ( I could feel the lump in the harness) and opened it up to investigate. As I recall, no one else here knew of its existence. You can see the Bl/w wires in my eBay sacrificial harness (I removed the connector for replacement) as well as the pink -negative buss connector. The removed +positive buss connector was yellow and exactly the same as the yellow - ground buss connector found behind the right headlight. Why HONDA chose to use a yellow connector for the positive buss and pink for the ground buss there is beyond me. 18ACA074-EF0C-4758-A1D7-53212F676D25.jpeg
 
Trapperdog said:
I do not believe so as I couldn’t find it either. When diagnosing my ‘09 1300P with the same issue, I happened on it accidentally ( I could feel the lump in the harness) and opened it up to investigate. As I recall, no one else here knew of its existence. You can see the Bl/w wires in my eBay sacrificial harness (I removed the connector for replacement) as well as the pink -negative buss connector. The removed +positive buss connector was yellow and exactly the same as the yellow - ground buss connector found behind the right headlight. Why HONDA chose to use a yellow connector for the positive buss and pink for the ground buss there is beyond me. 18ACA074-EF0C-4758-A1D7-53212F676D25.jpeg
Click to expand...
I have a 2003-2007 manual with PA (police) addendum. It does show the yellow 14 pin buss with all BL/W wires on the right side of the wiring diagram near the ECM. I didn't catch that you had a PA. I don't know if this applies to the ST1300A and ST1300AA versions but obviously there is some sort of Buss or multi point connection for the BL/W wires.
 
CruSTy said:
I have a 2003-2007 manual with PA (police) addendum. It does show the yellow 14 pin buss with all BL/W wires on the right side of the wiring diagram near the ECM. I didn't catch that you had a PA. I don't know if this applies to the ST1300A and ST1300AA versions but obviously there is some sort of Buss or multi point connection for the BL/W wires.
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Interesting, I don’t remember seeing that in my manual so will have to look again! I’m not 100% sure, but I believe the eBay harness I purchased was not off a P model. I do remember reviewing the harnesses for sale and picking one with an obvious lump in the harness in pics there though.
 
Trapperdog said:
Interesting, I don’t remember seeing that in my manual so will have to look again! I’m not 100% sure, but I believe the eBay harness I purchased was not off a P model. I do remember reviewing the harnesses for sale and picking one with an obvious lump in the harness in pics there though.
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The work around I made should carry the load just fine and will not cause any further damage however if there is more corrosion or heat damage in that yellow connector the bike could have more issues down the road as you pointed out. Many thanks for posting.

If this were my bike having an issue like this I would report it to the NHTSA. Honda dealers were of little help to this owner. I would think Honda dealers would or should have access to a Technical Service Bulletin on this.
 
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Trapperdog said:
I could feel the lump in the harness) and opened it up to investigate. As I recall, no one else here knew of its existence
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It's probably not documented or listed as Honda probably considers it 'part and parcel' of the wiring harness.. It goes bad— get a new harness. Wrapped the way it is— it goes bad it could take a lot of the harness with it.
 
Other Honda models have these buss connections that have the same problems and can be remedied with solder or my preference is using wire nuts. Pull the buss plug-in apart and see which wires jumper to each other and then cut, strip and wire nut them together.
 
CruSTy said:
The work around I made should carry the load just fine and will not cause any further damage...…………..
Click to expand...

You wouldn't happen to have a picture of this jumper you made? I'm tracking down a similar issue.
 
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