[andyauger]

There was some discussion about whether or not permanently shorting the clutch switch would affect the way the bike runs. There was some discussion about whether or not the ECM can tell if the clutch switch is closed all the time. Short story, no, the ECM can't "see" the clutch switch.

I took a look at the circuits for first generation and 2003 SVs (those are the schematics I have). The clutch is a simple interrupt between the starter button and the relay. There is a hot supply that comes from the run/stop switch that provides power to the start button, power to both coils, and connects to a pole on the ECM. But there is no signal available from the clutch switch to the ECM.

Looking at it another way, the circuit is the same electrically when the clutch is engaged and/or when the starter button is not depressed: open circuit. To complete the circuit the clutch has to be disengaged AND the starter button has to be pushed.

 

[JPDD]

Interesting and you are probably 99.99% correct. Who wants to be the 1st to verify Andy's conclusions?

 

[andyauger]

See, this isn't one of those cases where I can be partly right. It's all or nothing. The circuit is pretty simple, take a look.

 

[jbswear]

Interesting and you are probably 99.99% correct. Who wants to be the 1st to verify Andy's conclusions?

I've been verifying it for years.

 

[RandyO]

I remember reading one complaint in one thread about a 2nd gen not running as smooth after bypassing the clutch safety switch

my theory is that then the bike went down and broke the clutch safety switch, it also jarred the throttle bodies out of adjustment a bit

instead of going thru the bike after the incident, just blame the engine smoothness on a bypassed safety switch

 

[jbswear]

Your diagnosis of the switch is correct. It's nothing more than another kill switch in the ignition circuit (of which there are three, not counting the rev limiter or tip over sensor).

 

[jpramondon]

Looks like my mod is a bit of an overkill then ... (see my post).

Thanks for the input, this should definitly put an end to rumors.

J

 

[tcl]

Thanks Andy. I'd argue with you but since mine had been shorted for the last 20,000 miles, I'm happy to believe you this time.

 

[Veee]

There was some discussion about whether or not permanently shorting the clutch switch would affect the way the bike runs. There was some discussion about whether or not the ECM can tell if the clutch switch is closed all the time. Short story, no, the ECM can't "see" the clutch switch.

I took a look at the circuits for first generation and 2003 SVs (those are the schematics I have). The clutch is a simple interrupt between the starter button and the relay. There is a hot supply that comes from the run/stop switch that provides power to the start button, power to both coils, and connects to a pole on the ECM. But there is no signal available from the clutch switch to the ECM.

Looking at it another way, the circuit is the same electrically when the clutch is engaged and/or when the starter button is not depressed: open circuit. To complete the circuit the clutch has to be disengaged AND the starter button has to be pushed.

wrong.
first generation clutch switch is simply in line on power wire from starter button to starter relay.
second generation clutch switch is not in line with power or anything else. it is ground for relay with tail of it going to ECU. when you pull clutch relay and ECU gets grounded.
first generation rev limiter is cutting power.
second generation rev limiter is cutting fuel supply.

 

[tcl]

wrong.
first generation clutch switch is simply in line on power wire from starter button to starter relay.
second generation clutch switch is not in line with power or anything else. it is ground for relay with tail of it going to ECU. when you pull clutch relay and ECU gets grounded.
first generation rev limiter is cutting power.
second generation rev limiter is cutting fuel supply.

Ok, so why does the ECU listen to this and where can I cut the wire to the ECU so it doesn't know I've shorted the switch... and ... will the bike be hard to start cold or something if I do so?

 

[Veee]

Ok, so why does the ECU listen to this and where can I cut the wire to the ECU so it doesn't know I've shorted the switch... and ... will the bike be hard to start cold or something if I do so?

I believe reason ECM listen to this is to give more fuel for starting.
basically compensation for map that is in there.
I don't think it matters that you bypassed it, once motor starts running water sensor and air sensor and rest of system take over.

 

[jpramondon]

I don't think it matters that you bypassed it, once motor starts running water sensor and air sensor and rest of system take over.

Alright, but isn't there a fuel mapping over these sensors anyways ? (a changed one I mean).
Oh s**t, I'm starting to believe it again ... ;D

J

 

[jpramondon]

wrong.

Wow man, you've got guts ... ;D

J

 

[Veee]

Alright, but isn't there a fuel mapping over these sensors anyways ? (a changed one I mean).
Oh s**t, I'm starting to believe it again ... ;D

J

basic map is IAP, CKP and TPS. other sensors are compensation.
if something fails ECM will go to safe mode. clutch switch will not trigger safe mode on sv. like I said, I believe its only function is to tell ECM you starting bike and ECM sends more fuel for start up (actually it is just timing, longer injection since pressure and flow is constant).

 

[andyauger]

Veee, why do you say that? It's a one-wire system with two interrupt switches in series.

First generations and '03 are wired identically. The clutch switch and the starter button are in series. There are two wires on the clutch switch, two wires on the starter button, no wires tapped off between them.

One wire is the hot feed to the starter button. The other wire out of the starter button goes to the clutch switch. On the clutch switch there is the one wire from the starter, the other to the starter relay. Both switches have to be made for the starter to spin. If either switch is open (clutch released or starter button not being pushed) the circuit is open. Like I said, one continuous wire with two on-off switches in series.

That's it. Since the two switches are in series and there are no other wires between them there is no signal to the ECU that tells it which of the two switches are open or if both switches are open or if one is constantly closed. The only possible feed to the ECU would be when BOTH switches are closed and the starter is spinning.

If you have a later model schematic send it to me and I can look at it.

Forgot to add that the wire you may be looking at going to the ECU from the run/stop switch is always hot when the key is on and the run/stop switch is in the run position.

 

[Veee]

If you have a later model schematic send it to me and I can look at it.

I thought you looked at 03 schematic??
if that page is to small and hard to follow wires you can always check page 4-13.

 

[Chubblebeeks]

I've been verifying it for years.

+1. Six to be exact...

 

[swiest152]

Wow man, you've got guts ... ;D

J

not guts if you know your sh!t.

 

[imdying]

Short story, no, the ECM can't "see" the clutch switch.

Clutch position switch on the SV1000 K5- shorts pin 48 on the ECUs second plug (the larger one) to ground.

(the yellow/black wire)

Ok, so why does the ECU listen to this and where can I cut the wire to the ECU so it doesn't know I've shorted the switch... and ... will the bike be hard to start cold or something if I do so?

If uses a different ignition map (and presumably fuel map) when the clutch is in, or the bike is in neutral. You'd have to check bozo's work for details though.


/edit: A good test for this is on TRE fitted bikes... sit in neutral with the bike at the lights... ECU thinks (because of the TRE) it's in 5th or whatever gear it is you chose). Pull clutch in, idle changes, let it out, idle returns. Basically you're telling it, I'm in 5th, clutch is in so use the neutral map, repeat... And it applies the map to suit. Now, having not seen the ECU code, I couldn't tell you if there's a sepearate map for neutral and clutch in, but bozo would probably know... however, the reason you only see this on a TRE equipped bike is because you're going 5th/clutch/5th, instead of neutral/clutch/neutral; so given neutral/clutch/neutral doesn't show it up, then it seems likely that the neutral/clutch in maps are the same.

 

[Marc]

If after your bike is all warmed up and you can hear a differance in the way it runs or sounds by pulling the clutch lever then I would disconnect the wire that goes to the ECU that the switch is gounding when pulled, if you want to bypass the clutch switch. I'm thinking it may be retarding the ignition timing slightly along with a adding a little more fuel for easy starting. That may make it start harder but you might as well make the ECU think the switch is off after the bike starts.