F1 light

[okiehick82]

I could use some advice. I have a well maintaned high mileage (85,000) 2003 ST1300. Several time in the last few months when pulling my trailer at interstate speeds plus (speedo reads about 80) the F1 light comes on solid no flash. If I turn off the key and restart it disappears. I hadn't noticed it running bad though the milage may have dropped off a bit. I know don't pull the trailer 80 idiot. There got that out of the way. I have run Lucas fuel injector cleaner through 4 or 5 tanks now hoping to have an easy fix. No luck. Today I decided to do an experiment in 3rd gear did a slow throttle roll on at about 4600 rpm felt a slight stutter and the F1 light came on. With out resetting the light tried to repeat the stutter never happened again. Going to dig into the service manual but any advice would sure help. Thanks in advance. John

 

[Blrfl]

If it happens at around 4,300 RPM, you've likely lost a knock sensor. Usually, it's either the wiring or the ECM.

Start by pulling the fault codes.

--Mark

 

[okiehick82]

Thanks Mark. Dragging out the manual tomorrow to see what I can learn. I have never messed with the codes so I will have to figure out how to read them.

 

[okiehick82]

I have tried to read a code both on the side stand and the center stand both running and not running. No flashing lights. I haven't had the time to short out the plug per the manual. Am I missing something. The light is flashing on a little before 4500 rpm.

 

[Igofar]

I hope you don't find what I just found on a 2009 police motor....
Found a melted wire on the lower neutral switch (bare metal touching engine), both knock over sensor tab's broken off and the switch just resting on other half loose, and the three wires coming off the back of the water temp. sensor assembly bare metal, and appeared to have been chewed :sm1: we had to replace the entire sub wire crankcase wiring harness (which is nothing you want to do).
Before you start throwing money at your bike and replacing electrical switches, you may want to lift the tank and air box base, lift the rubber mat and look around with a mirror and a flashlight for damage or nests.
.02

 

[Igofar]

I could use some advice. I have a well maintaned high mileage (85,000) 2003 ST1300. Several time in the last few months when pulling my trailer at interstate speeds plus (speedo reads about 80) the F1 light comes on solid no flash. If I turn off the key and restart it disappears. I hadn't noticed it running bad though the milage may have dropped off a bit. I know don't pull the trailer 80 idiot. There got that out of the way. I have run Lucas fuel injector cleaner through 4 or 5 tanks now hoping to have an easy fix. No luck. Today I decided to do an experiment in 3rd gear did a slow throttle roll on at about 4600 rpm felt a slight stutter and the F1 light came on. With out resetting the light tried to repeat the stutter never happened again. Going to dig into the service manual but any advice would sure help. Thanks in advance. John

I'd start with new plugs, new TB hoses, clean the 5-way tee, and do a throttle body sync.
Then start looking for other issues.

 

[Blrfl]

The light is flashing on a little before 4500 rpm.

Yep, that's pretty classic knock sensor.

Sensor failures aren't unheard-of, but they do happen. On early bikes like your 2003, there's some history of the wiring near one of the sensors having been misrouted and ending up melted. (That can either be fixed by hand or the sub-harness it's on can be replaced for about $55.) More common is a failure of the circuit inside the ECM that interfaces the sensor to the computer. That, unfortunately, requires that the ECM be replaced. Running down the culprit isn't difficult; so get the fault code out of the ECM and we'll go from there.

I'll disagree with Larry; this is not a vacuum-hoses-and-5-way-tee problem. Don't mess around with anything else on the bike until you've resolved this problem.

--Mark

 

[Igofar]

Yep, that's pretty classic knock sensor.

Sensor failures aren't unheard-of, but they do happen. On early bikes like your 2003, there's some history of the wiring near one of the sensors having been misrouted and ending up melted. (That can either be fixed by hand or the sub-harness it's on can be replaced for about $55.) More common is a failure of the circuit inside the ECM that interfaces the sensor to the computer. That, unfortunately, requires that the ECM be replaced. Running down the culprit isn't difficult; so get the fault code out of the ECM and we'll go from there.

I'll disagree with Larry; this is not a vacuum-hoses-and-5-way-tee problem. Don't mess around with anything else on the bike until you've resolved this problem.

--Mark

I agree with Mark, which is why my first reply was about the knock sensors and wiring
I only threw the second comment out here because of the mileage and year of the bike.
I should have stated that after you resolve your electrical issues (FI light) you should replace the lines, clean the tee, and do some further service.
Sorry for the confusion (very late night last night).
Igofar

 

[Don B]

I have tried to read a code both on the side stand and the center stand both running and not running. No flashing lights. I haven't had the time to short out the plug per the manual. Am I missing something. The light is flashing on a little before 4500 rpm.

Easy way to get the codes is park the bike with the FI lite still on, don't turn off the ignition, kill the engine by shifting into gear then putting the side stand down. Leave the ignition turned on and the FI lite should begin flashing the code to you. Once the ignition is turned off, the FI lite won't show the code again until the fault is detected again.

 

[okiehick82]

Easy way to get the codes is park the bike with the FI lite still on, don't turn off the ignition, kill the engine by shifting into gear then putting the side stand down. Leave the ignition turned on and the FI lite should begin flashing the code to you. Once the ignition is turned off, the FI lite won't show the code again until the fault is detected again.

Thanks for the tip. I hadn't thought of that solution. Now I just have to get the light to come on again. It o,lye happens when I am on it pretty hard. Guess now I have an excuse to go wring it out. Thanks. I will tell the cop I am just try to get the trouble light to come on. Lol

 

[okiehick82]

If it happens at around 4,300 RPM, you've likely lost a knock sensor. Usually, it's either the wiring or the ECM.

Start by pulling the fault codes.

--Mark[/QUOTE

Can an you give me a little help with the location of the knock sensor?

 

[wjbertrand]

The debate about whether it's a vacuum line / MAP sensor or knock sensor issue should be settled pending the code discovered.


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[Qomar]

Usually the problem is with the knock sensor either on the left or right. I have been discus about this thing with some friend and they told the real problem is with the CCU. Mine ST 04 facing the same problem but I just ignore it coz it is so expensive to but a new CCU

 

[Don B]

Can an you give me a little help with the location of the knock sensor?

There are not any photos in the service manual that I could find of the location of the sensors, but there is an illustration on page 5-5 in the SM (page heading is SYSTEM LOCATION). There is also an illustration in the GENERAL INFORMATION chapter on page 1-33 in my SM that shows the location of the left bank knock sensor. (Note that page number reference may be incorrect for other editions of the SM). There are additional illustrations deeper in Chapter 5 that are a little more detailed. I can't tell for certain if the sensors are located on the cylinder heads or on each side of the block, but they shouldn't be hard to find once the Tupperware is removed from the bike. Be sure the engine is cooled down before you start looking for the connectors on the sensors, since they are in very close proximity to the exhaust headers.

Hope this helps if your problem turns out to be one of the knock sensors.

 

[okiehick82]

You guys are the best I used the advice given to read the code. I got 2 long 5 short 25 flashes. Left knock sensor great diagnosis. I am off to order a new sensor. If I am going to strip off the Tupperware I am going to put in a new sensor. Thanks for all your help. I hope it is just a bad sensor not burnt wires or poor wiring from the factory. Thanks again for all the help. Love my ST. Love my STOWNERS site.

 

[Igofar]

One thing to think about before you start ordering parts...when the 5 way tee is clogged up, it throws a code instructing you to replace the map sensor switch, even though its just goop in the lines that the map sensor is connected too.
A burnt or melted wire (touching the engine near the exhaust system) could also read as knock sensor switch, since that's the wire its connected too.
I'd look for melted/damaged wires and stuff first.
If you find damaged wires, you MUST replace the entire crankcase sub wiring harness as a whole unit (ask me how I know).
I would start, with the free and easy stuff first. Check the 5 way tee and do a TB sync first....you can always throw money at it later.

 

[Don B]

You guys are the best I used the advice given to read the code. I got 2 long 5 short 25 flashes. Left knock sensor great diagnosis. I am off to order a new sensor. If I am going to strip off the Tupperware I am going to put in a new sensor. Thanks for all your help. I hope it is just a bad sensor not burnt wires or poor wiring from the factory. Thanks again for all the help. Love my ST. Love my STOWNERS site.

I suggest you re-read Birfl's post #7. It's unusual for knock sensors to fail, more likely to be either a wiring problem or failed ECU. Get your multimeter out and perform the checks described in the SM to isolate the problem before you start ordering replacement parts that you don't need, or won't resolve the problem. One suggestion I have if your ST has ABS, the ECU is difficult to access, so consider making the checks for opens and shorts in the wiring from the sensor connector through the sub-harness before checking all the way to the ECU connector.

The part of this procedure that I don't have the answer to is where the sub-harness connects to the main harness. Hopefully, someone here who has done this before can chime in with that connector's location, and hopefully which pin(s) to connect the meter to. Is anybody home?

 

[Blrfl]

You guys are the best I used the advice given to read the code. I got 2 long 5 short 25 flashes. Left knock sensor great diagnosis. I am off to order a new sensor.

Don't do that until you go back and re-read what I wrote in post #7. The sensors are rarely the cause, and you can rule it out buy swapping them and seeing if the problem moves to the opposite side.

Unrelated: The revs needed to make the code show up aren't anywhere near wringing it out. If you're not crossing through 4,500 RPM on a regular basis, you may want to consider not riding it like it's a V-twin. You're missing out on the places where this engine really sings, and running it too slow under load doesn't do it any favors.

Check the 5 way tee and do a TB sync first....you can always throw money at it later.

I know that's your favorite thing, it's better not to add variables to the situation by changing things on other parts of the bike when trying to diagnose something that's already known to be a problem.

--Mark

 

[Igofar]

I have had a couple folks come through lately, with the FI light issue, and they were told it was the knock sensor(s). They turned out not to be the issue at all, after spending $90 bucks each! The clogged 5 way tee turned out to be the problem, as it was clogged up and the higher rpm was moving stuff around inside the lines....just saying, its free and easy to check before purchasing parts.
The most recent, 09 police motor, had FI lights on and off at random, then started having starting issues....this was found to be melted/chewed sub wire harness.
You just have to check everything, as the FI light issue is not always as it appears.

 

[Don B]

I have had a couple folks come through lately, with the FI light issue, and they were told it was the knock sensor(s).

The question that first comes to mind is who told them the problem was knock sensor(s)? Could it be someone who didn't bother to diagnose the codes to come to that conclusion? The FI light can be lit up by any one or more causes. The diagnostic codes may well have pointed to a problem related to the 5-way T if anyone really bothered to check.