Code 26. Two long blinks followed by 6 short blinks. Right Knock Sensor.
Well, maybe. I originally piggybacked this onto another thread but now I think my story deserves its own thread. No, all stories don't have happy endings.
Running the engine above 3900 RPM for 10 seconds will generate this fault code. Instantly power is cut, and fuel mileage plummets. 3900 RPM looks like 72 mph on the speedometer. It is 68 mph on the GPS. This fault will give you 37 mpg at 73-74 GPS mph on the Interstate.
First, if the red FI light in the dash comes on you must read the code. Reading the code is very simple. If you know how. Engine running, FI light on, bike in neutral, lower the kickstand. Then count the blinks. A long blink (1.3 seconds) counts as 10. In my case two long followed by 6 short equals 26.
Your Genuine Honda Service Manual will have a chart telling you what the # of blinks translates into. My bike is an '04 so this is found on pages 5-14 thru 5-16.
A quick and desperate check of both ST forums told me that most often the problem was not the sensor. It is the plug and or wiring breaking down from the intense heat of its location. Cutting off the plug and replacing with a suitable spade connector solved almost everyone's issues.
I removed all the Tupperware from the right side. I unplugged the knock sensor. It is inconveniently located between the exhaust header pipes and the engine block. I checked the plug and it looked fine.
The troubleshooting section of the Honda Service Manual says to check for continuity to ground from the plugs on either end of the wiring harness. Then it says to check for continuity between the two plugs. Basically, you are checking to see if the wire has been damaged and is going to ground or has burned/rubbed/broken in two between the sensor and the ECU. If it is not going to ground and the wire is intact, the problem must be the sensor.
*Problem*
The Honda Manual is WRONG concerning the wire colors for my '04 ST. It clearly states on pages 5-49 and 5-50 that the wire colors are:
Left Sensor Wire-Blue
Right Sensor Wire-Red/Blue
This is not correct for my bike. The manual has two sections for two different year groups. The first is for '03-'07. The second is for '07 and later.
My ST is wired like the '07 and later version. My sensor wires were:
Left Sensor Wire-Red/Blue
Right Sensor Wire-Black
Using the wire colors the manual stated for my year I decided the wire between the sensor and the ECU was bad. I ran a temporary wire and cut/spliced into the wiring harness just ahead of the ECU. Tried running the bike, still got the code. Purely by accident I looked at the section for '07 and later and was able to re-diagnose the wiring.
I wound up removing the left side Tupperware during the confusion phase so I tried running separate wires under the bike to "switch sides" with the sensors. I stuck the stripped ends of #14 wire into the female sensor plugs and used spade connectors to attach the other end of the wires to the sensors. No code. Re-connected the plugs. Got Code. Stuck wires back in, Ran bike. No code. R-connected plugs. Got Code.
Sigh... Plugged left sensor back in. Jammed wire back into female plug on right side and plugged spade connector onto right knock sensor. No code.
Decided the connectors inside the female end were "sprung" out and not making good connection to sensor. I found that the plug (sensor end) was not making a good connection at the sensor. I attempted to use a tiny screwdriver to pry the metal connectors out and...
The plug shattered in my hands. The more I tried to repair, the more the brittle plastic crumbled in my hands. I replaced the plug with a tiny spade connector.
Ran the bike on the centerstand, no code. Fixed it!
Or not...
Over the next couple of weeks the 26 Code would re-appear. It was intermittent, it was unpredictable. No correlation to humidity, weather, temperature, or bike temperature could I find. I lost confidence in my ST and in my own troubleshooting skills. I began to doubt myself and my bike. I need to have confidence that if I have to I can get on my motorcycle Right This Minute and ride it Coast to Coast. If I can't trust the reliability of the bike, I don't need it.
I removed the Tupperware several times to check my connection. I removed and re-connected the ECU several times. I double checked everything.
I decided that the resistance of the wire between the new spade connector and the plug at the ECU was too high. It is at most 5-6 feet of wire but there was about 4 ohms of resistance in that short length of wire. I would have expected 0.4 ohms, not 4.0 ohms. I replaced the factory wire by running a separate length of wire with a high temperature insulation. I felt confident. Ran on centerstand, no code! Success!
Well, no. Continued to get code intermittently.
Now I am so depressed and disgusted that I am making everyone around me miserable. The ST is such a huge part of my identity and thinking that I am more affected than I ought to be. Yamaha announces the '14 FJR in Candy Red. Factory Cruise Control, electronic suspension, traction control, heated grips... Oh man, things are getting bad. Mrs. Redfish finally says, "I know you don't like giving up but...have you considered buying a new bike?"
I removed the Tupperware. Again. I poked around the sensor connection. Again.
Definition: Stupidity- Doing the same thing over and over expecting different results.
Then I remembered. I am an I&E Technician. I routinely troubleshoot and repair equipment that costs more than my (wife's) house and can affect millions and millions of dollars worth of production. I am supposed to know things.
What is a knock sensor anyway? It senses vibration. It would be called a vibration sensor in an industrial application. In the presence of vibration a millivoltage charge is generated by the sensor. The computer reads that millivoltage signal and interprets the amount of vibration present.
I had already installed two excellent test points at the ECU plug in the form of two butt splices. I connected my meter and started the bike.
I found that both the right and left knock sensors generated about -114.5 millivolts with the bike idling. Both generated about -122 millivolts at 4100 RPM. No appreciable difference between right and left sensor. No spiking, no dropping, no PROBLEMS!
Yet, I am still getting the code. Now, I get it all the time. I check the connectors in the ECU plug. I gently pry (with a fish hook) to get a bit more tension. I am sure there is no problem with the plug.
I cut the wires. Again. I use wire nuts to temporarily switch the left and right wires where they go into the ECU plug. I run the bike.
Still getting the 26 code. If the problem was in the wiring or the sensor, the code would have changed to the Left Knock Sensor, Code 25. But it didn't.
At this point I have determined the ECU is faulty. The PGM-FI is about $825 online.
I'm going to go drink a beer now.
Well, maybe. I originally piggybacked this onto another thread but now I think my story deserves its own thread. No, all stories don't have happy endings.
Running the engine above 3900 RPM for 10 seconds will generate this fault code. Instantly power is cut, and fuel mileage plummets. 3900 RPM looks like 72 mph on the speedometer. It is 68 mph on the GPS. This fault will give you 37 mpg at 73-74 GPS mph on the Interstate.
First, if the red FI light in the dash comes on you must read the code. Reading the code is very simple. If you know how. Engine running, FI light on, bike in neutral, lower the kickstand. Then count the blinks. A long blink (1.3 seconds) counts as 10. In my case two long followed by 6 short equals 26.
Your Genuine Honda Service Manual will have a chart telling you what the # of blinks translates into. My bike is an '04 so this is found on pages 5-14 thru 5-16.
A quick and desperate check of both ST forums told me that most often the problem was not the sensor. It is the plug and or wiring breaking down from the intense heat of its location. Cutting off the plug and replacing with a suitable spade connector solved almost everyone's issues.
I removed all the Tupperware from the right side. I unplugged the knock sensor. It is inconveniently located between the exhaust header pipes and the engine block. I checked the plug and it looked fine.
The troubleshooting section of the Honda Service Manual says to check for continuity to ground from the plugs on either end of the wiring harness. Then it says to check for continuity between the two plugs. Basically, you are checking to see if the wire has been damaged and is going to ground or has burned/rubbed/broken in two between the sensor and the ECU. If it is not going to ground and the wire is intact, the problem must be the sensor.
*Problem*
The Honda Manual is WRONG concerning the wire colors for my '04 ST. It clearly states on pages 5-49 and 5-50 that the wire colors are:
Left Sensor Wire-Blue
Right Sensor Wire-Red/Blue
This is not correct for my bike. The manual has two sections for two different year groups. The first is for '03-'07. The second is for '07 and later.
My ST is wired like the '07 and later version. My sensor wires were:
Left Sensor Wire-Red/Blue
Right Sensor Wire-Black
Using the wire colors the manual stated for my year I decided the wire between the sensor and the ECU was bad. I ran a temporary wire and cut/spliced into the wiring harness just ahead of the ECU. Tried running the bike, still got the code. Purely by accident I looked at the section for '07 and later and was able to re-diagnose the wiring.
I wound up removing the left side Tupperware during the confusion phase so I tried running separate wires under the bike to "switch sides" with the sensors. I stuck the stripped ends of #14 wire into the female sensor plugs and used spade connectors to attach the other end of the wires to the sensors. No code. Re-connected the plugs. Got Code. Stuck wires back in, Ran bike. No code. R-connected plugs. Got Code.
Sigh... Plugged left sensor back in. Jammed wire back into female plug on right side and plugged spade connector onto right knock sensor. No code.
Decided the connectors inside the female end were "sprung" out and not making good connection to sensor. I found that the plug (sensor end) was not making a good connection at the sensor. I attempted to use a tiny screwdriver to pry the metal connectors out and...
The plug shattered in my hands. The more I tried to repair, the more the brittle plastic crumbled in my hands. I replaced the plug with a tiny spade connector.
Ran the bike on the centerstand, no code. Fixed it!
Or not...
Over the next couple of weeks the 26 Code would re-appear. It was intermittent, it was unpredictable. No correlation to humidity, weather, temperature, or bike temperature could I find. I lost confidence in my ST and in my own troubleshooting skills. I began to doubt myself and my bike. I need to have confidence that if I have to I can get on my motorcycle Right This Minute and ride it Coast to Coast. If I can't trust the reliability of the bike, I don't need it.
I removed the Tupperware several times to check my connection. I removed and re-connected the ECU several times. I double checked everything.
I decided that the resistance of the wire between the new spade connector and the plug at the ECU was too high. It is at most 5-6 feet of wire but there was about 4 ohms of resistance in that short length of wire. I would have expected 0.4 ohms, not 4.0 ohms. I replaced the factory wire by running a separate length of wire with a high temperature insulation. I felt confident. Ran on centerstand, no code! Success!
Well, no. Continued to get code intermittently.
Now I am so depressed and disgusted that I am making everyone around me miserable. The ST is such a huge part of my identity and thinking that I am more affected than I ought to be. Yamaha announces the '14 FJR in Candy Red. Factory Cruise Control, electronic suspension, traction control, heated grips... Oh man, things are getting bad. Mrs. Redfish finally says, "I know you don't like giving up but...have you considered buying a new bike?"
I removed the Tupperware. Again. I poked around the sensor connection. Again.
Definition: Stupidity- Doing the same thing over and over expecting different results.
Then I remembered. I am an I&E Technician. I routinely troubleshoot and repair equipment that costs more than my (wife's) house and can affect millions and millions of dollars worth of production. I am supposed to know things.
What is a knock sensor anyway? It senses vibration. It would be called a vibration sensor in an industrial application. In the presence of vibration a millivoltage charge is generated by the sensor. The computer reads that millivoltage signal and interprets the amount of vibration present.
I had already installed two excellent test points at the ECU plug in the form of two butt splices. I connected my meter and started the bike.
I found that both the right and left knock sensors generated about -114.5 millivolts with the bike idling. Both generated about -122 millivolts at 4100 RPM. No appreciable difference between right and left sensor. No spiking, no dropping, no PROBLEMS!
Yet, I am still getting the code. Now, I get it all the time. I check the connectors in the ECU plug. I gently pry (with a fish hook) to get a bit more tension. I am sure there is no problem with the plug.
I cut the wires. Again. I use wire nuts to temporarily switch the left and right wires where they go into the ECU plug. I run the bike.
Still getting the 26 code. If the problem was in the wiring or the sensor, the code would have changed to the Left Knock Sensor, Code 25. But it didn't.
At this point I have determined the ECU is faulty. The PGM-FI is about $825 online.
I'm going to go drink a beer now.
