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Discussion Starter · #1 ·
Okay so not sure if anyone saw my last post but I ended up figuring out why my ODO was only reading CHEC with no FI light or anything with a solid Neutral light on. Ended up being my gear indicator sensor plugged into a wrong plug.
this is a crashed K4 GSXR 1000 and I’ve been rebuilding it and finally was able to try and fire it up.

But now the bike has a blinking FI light with a -C23 code which is a TOS (tip over sensor) from what I’ve read and it also has a -C46 code but pretty sure that is just a exhaust valve code or something unimportant. The bike has spark and wants to start sometimes, the fuel pump primes but it’s like it’s not priming all the way from what I remember and you can tell because it just Stops suddenly in the middle of priming. Would that be a fuel pump relay issue? I can hear the relay clicking or making the sound as it should to tell it’s working, but I don’t know forsure if it’s actually working properly...
It’ll fire up SOMETIMES if I hold the throttle wide. Not sure if these are symptoms of a bad TOS or not and it’s confusing me because from what I’ve read the bike should still run if it isn’t plugged in and I’ve unplugged it, I also tried taking it apart to see if anything was broken or if I could possibly try and do a bypass like everyone says by putting some caulk in there or something to keep the magnet in the on position. I even tried a second TOS that came off a spare harness I bought with no luck the bike still didn’t want to fire and stay running.
I also have this little plug that is unplugged from something and I’m not sure where it goes or what goes to it, but I’m assuming if it was anything important it would throw a code also right??? It’s only a little 2 pin plug it’s white and the shape of a rectangle. I can add pictures later just not near the bike right now lol.
Anyways guys ANY help is very much appreciate! Thank you!
 

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Suzuki isn't as clear as they could be about the TOS. I ran into this with the ECT sensor and spent some time sorting that out. I'd expect what I found to apply to the TOS but no guarantee. Also note that your K4 uses a similar but different part than my K6.

C23 means that the sensor is malfunctioning or the wiring from it to the ECM is faulty. Malfunctioning is different than being in a tip-over condition, which does not cause a C23. The normal output signal to the ECM is about 1 V. It jumps to 4.4 V when tipped over (the TOS has a bistable circuit that is tripped by a magnet on a pivot), which causes the ECM to cut off fuel to the injectors. Don't know if this is simply not pulsing the injectors or if the fuel pump is also turned off. If the TOS malfunctions such that the voltage to the ECM is less than .2 V or greater than 4.8 V, a C23 will be produced. This apparently also causes the ECM to enter a "cannot start" mode with the blinking LED and may also enter the more severe "cannot run" state.

So measure the TOS signal at the ECM and proceed from there.

The C46 is just complicating things. There are some straightforward ways to get rid of it.

What are the colors of the leads to the two pin connector?
 

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Discussion Starter · #3 ·
Pardon my stupid Question, but you test those wired by sticking the multimeter into the ECM plug right? Trace the same wires from the TOS Plug back to the ECM plug and test there? Or ..? Do you mean test the current on the wires to the TOS plug itself?? Sorry Electrical is my weak point I’m pretty good with mechanical shit but electrical is another story haha
 

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Discussion Starter · #4 ·
Suzuki isn't as clear as they could be about the TOS. I ran into this with the ECT sensor and spent some time sorting that out. I'd expect what I found to apply to the TOS but no guarantee. Also note that your K4 uses a similar but different part than my K6.

C23 means that the sensor is malfunctioning or the wiring from it to the ECM is faulty. Malfunctioning is different than being in a tip-over condition, which does not cause a C23. The normal output signal to the ECM is about 1 V. It jumps to 4.4 V when tipped over (the TOS has a bistable circuit that is tripped by a magnet on a pivot), which causes the ECM to cut off fuel to the injectors. Don't know if this is simply not pulsing the injectors or if the fuel pump is also turned off. If the TOS malfunctions such that the voltage to the ECM is less than .2 V or greater than 4.8 V, a C23 will be produced. This apparently also causes the ECM to enter a "cannot start" mode with the blinking LED and may also enter the more severe "cannot run" state.

So measure the TOS signal at the ECM and proceed from there.

The C46 is just complicating things. There are some straightforward ways to get rid of it.

What are the colors of the leads to the two pin connector?
I’ll get back to you on those wire colors
 

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A tip over will cause a C23. Be careful trying to test from the ECM harness. Inserting probes can damage sockets and just make things worse. I advise using thin sewing needles to probe from the back.
 

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Discussion Starter · #6 ·
A tip over will cause a C23. Be careful trying to test from the ECM harness. Inserting probes can damage sockets and just make things worse. I advise using thin sewing needles to probe from the back.
Still a little confused on how I go about testing them? I just stuck my multimeter in all the sockets on the ecm plugs and only a few are putting out high voltage around 12 and most of them don’t show any voltage or very low voltage not sure if that’s normal or not? If there really was voltage suppose to be there How would the bike fire up?? The bike has good spark and I would assume a fault in the wiring would cause no spark. Also I ended up soldering the oil pressure sensor wire together because that was one of the few wires that tore on impact so not sure if that’s why it’s blinking or what. More than likely not, I just thought’d I’d say that.
I also tried testing right at the TOS plug itself and it also showed no voltage on either 3 of the wires the red, black, and black with brown stripe. And this was all with the key turned on not sure if I’m even doing this correct or what. Sorry guys I just need to be pointed in the right direction and I’ll be good after that haha
 

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Sewing needles carefully inserted into the connector while connected is the way to go. It's easier if you solder a fine wire onto the end of the needle and connect the multimeter to it instead of directly to the needle. Insert the needle between the lead being tested and the rubber seal around it. Insert until it is touching the connector contact. The seal will tend to hold the needle in place. Note that you're measuring voltage, not current.

The R lead to the TOS is 5 V sensors power from the ECM. So the ECM must have power. That means both the ignition and kill switches must be on. The R lead runs to other sensors and can be checked at the eight pin Suzuki Access Port (near by the dealer mode connector). B/Br is sensors ground.

I've measured the voltage on the B lead from the TOS and observed it jumping from 1 V to 4.4 V. As said, I'm not sure about a tip-over condition causing C23 and The Geek could be right there. But if so the service manual is in error as it clearly states that C23 only appears when the TOS output voltage is less than .2 V or greater than 4.8 V. I've observed similar confusion about the ECT and C15.

"I also tried testing right at the TOS plug itself"
If you're testing with the TOS unplugged, the R lead should be 5 V when the ECM has power (confirm at the SAP connector). That should also apply when the TOS is connected but, at least on my K6, it's hard to get at things then.
 

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Instructions to test the TOS are on page 4-43,44 in the FSM. Looks like a pretty simple procedure.
 
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