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Bike won't start, probably CKP (SIGNAL GENERATOR) Sensor

268 Views 5 Replies 2 Participants Last post by  TurboSkilla
Hi all,

Need some info and assistance testing the CKP sensor please,
Busy on a ride and the bike just cuts out while pulling away from traffic lights, it cut-out immediately as if the kill switch was hit. ( NOT stumbling or slowly dying )
It had very little fuel in it, so I thought it ran dry, pushed it 100m to the fuel station and filled up.
when I tried to start the bike, it wouldn't start.

No waring lights
Motor just swings without any ignition event (sparking) sounds.
Fuel pump can be heard priming when ign is switched ON

I left the bike at the station to fetch the pickup, when I got the the bike with the pickup, I tried to start it and it managed to "burble" (could hear it had an ignition spark event) but didn't start, after that no more sparking could be heard.
I dropped the bike off at a friends home
I Eventually got the bike home after 2 days and tried to start it, at this point it started perfectly and ran perfectly fine for about 15 seconds,
Just as I thought the issue resolved it self, it died again, I tried to start it but after it died, it would just swing again.

Leaving it for 2 more days, I tried starting it again, but still, only swings with no attempt to start. and no more sparking events
Hotwire the fuel pump to pump out all the fuel, so pump is running.
The fresh fuel was drained & filtered,
Fuel pump removed & Cleaned
Fuel filter replaced with new one. (35K km on the odometer)

Tried starting it after putting everything back together, but nothing, just swings,
Holding the started button down for 10 seconds, hoping that would prime the system better or assist in starting it, eventually the bike threw a "FI" code
Placing it in dealer mode, C12 error showed. C12 for my GSXR is for CKP sensor, (signal generator/crankshaft pos sensor)

I do not have the manual for the GSXS, but I have the manuals for all my other GSXRs, (hopefully someone feels like sharing one)

Had a look for the testing procedures for the CKP for the gsxr (hoping it'll be the same as the GSXS is based on the GSXR), these were the results:
Test 1: resistance test
it was sitting at 159 ohm, which is in range for the GSXR (unknown range for GSXS)

Test 2: Ground conductivity on the CKP wires connector
Both wired had conductivity to ground, manual stated to check metal particles on the sensor head, so i stripped the cover off, removed crankshaft gear to expose the sensor, removed the sensor and cleaned it as it maybe had I tiny amount of metal particles/shavings on the magnet side,a tiny bit, Nothing big enough to be worried about, or that would have made a grounding connection in my experience.

reinstalled the sensor and re did Test 2 to measure ground conductivity again, this time it had no conductivity to ground.

I reassembled everything and tried to start, nothing, no change, just swings.

I then went on to Test 3: Voltage output:
according to my GSXR manual, it should generate between 0.2v to 2v DC, doing the test returns 0v.
Now, my understanding of CKP type sensors ( HALL or RELUCTANCE types), is that variable reluctance sensors should generate AC voltage and not DC voltage as the GSXR manual says,
redoing the test in AC more on the multi-meter, I get 0.6v...

at this point im not positive that the sensor died, well, not 200 USD sure that the sensor died.
Does anyone have any idea what sensors GSXS use for crankshaft?
Could someone confirm the wire colours as well ? GSXRs uses striped wares, the GSXS uses solid black and solid green from the sensor, and stripped after the connector to the ECU.

Worst case, could someone maybe share a page or 2 for testing CKP sensors ? from the GSXS manual to just confirm the values and other details.

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Hi TurboSkilla,
I can share you some info from a 2017 Service Manual, but as I said to another person here, I won't send a complete manual by email.
Your pretty right with your conclusions as the R and S are much the same. The S resistance is 168 Ohms at 20C temp and as it is a coil, the open circuit voltage is a DC pulse of 0.5 V typical, so at 0.6 your OK.

The .pdf of 3 pages is all that this manual has on testing for a C12 code. If it gets the same voltage at the ECU unplugged connector end, then that leaves the ECU itself or a bad intermittent connection in the loom. I had a GSX-R1000 that had bad fuel, (only cranked over, it won't run) and I was told by the Service Advisor at the Shop, that if one spark plug dies, the bike will stop dead.
The CKP sensor I guess would be the thing that makes that safety cut out, as Suzuki say all the other sensors will allow the bike to crank and run even if they fail except for the CKP.



Thx, I see they refer to other sections for the actual values for the test results.

So if it is a 5v pulse, then it must be an HALL type sensor, which means I need to measure DC,
I got 0.6v on AC, not DC , So there might be an issue with sensor as DC wise it was 0v all the way.
Thx, I see they refer to other sections for the actual values for the test results.

So if it is a 5v pulse, then it must be an HALL type sensor, which means I need to measure DC,
I got 0.6v on AC, not DC , So there might be an issue with sensor as DC wise it was 0v all the way.
Hi TurboSkilla,
I'll bow down to your knowledge of CKP technologies. I assumed when they said 'sensor' we were still in the age of a pick up coil and a permanent magnet like material generating a sharp pulse. Like when the bikes had the sensor for the tacho on the front sprocket shaft.
Whether it is AC or DC pulse, the Manual doesn't say other than 0.5 OR MORE, but no top value given.
But the attachment of today gives you that values page that you really needed to read for yourself.
I have included the table in page 2 of the PDF. The last sentence down the bottom footer may be of some help as it pertains to the table 'yes' actions.
Best of Luck.



Thx Rob, Much appreciated, This is part of what I needed,

I now see what you were referring to with failsafe conditions,
seeing that the only condition that would make the bike not run, is when 2 or more IGN or Injector signals aren't received,

After checking that the same sensor is used in almost all GSXR & GSXS models, I stripped the same sensor out from one of my race bikes.

Will do the swop today and see what it gives me.
Even thou the GSXR series use the same sensor, the rubber moulding around the wires that seals the engine cases where the wires exit the case are different, so it is not a plug and play replacement.
so when buying a new one, make sure that it is the correct part number, otherwise, the wires will need to be cut between the sensor and the rubber moulding replace the actual sensor or, when in a pinch the rubber moulding can be cut and removed, then swopped over to the GSXR sensor and then just sealed up with some gasket maker to ensure no oil leaks.

Due to the entire sensor, including wires and connectors are not a direct swop out, I couldn't use the one from my race bike, so not wanting to cut up the rubber boot i
went to the scrap yard and got a sensor from a stripped GSXR ( the actual sensor is exactly the same).

I found out I know more swear words than I thought, even thou the Suzuki engineers designed the perfect bike according to me, man oh man, they can also make life difficult....the way the sensor wires are routed from the sensor, between and behind a very small narrowing between the engine cases, behind the cam chain tensioning guide sucks.....
You need to partially remove the cam chain tensioning guide, without pulling it off the tensioner, or breaking the thin plastic guide, and still wiggle and pull to massage the wires out as the loose protective sleeving that goes over the wires is almost to thick to pass through the narrowing while everything is covered with oil....

I did a bench test on all 3 sensors and all 3 sensors passed the tests (Thx Rob), if you don't have the special tool Suzuki refers to, the peak voltage adapter, it makes the tests less accurate, but still doable, most pickups, being Reluctance or Hall type can be test for basic functionality easily, it is not as accurate as measuring peak voltage, but still testable.
this can be done by setting your multimeter to resistance, as per test 1 in the manual, and measure the resistance, it should be somewhere in the range outlined in the manual, then using something metal, like a ratchet/socket extension, quickly place it on the sensor and remove it (almost as if you wanted to "tap" the sensor with the extension") you should see the resistance change a lot, mine was sitting at 165 ohm for the test, and it spikes to over 200.

So not wanting to cut and crimp/solder the new sensor to my bikes harness, I decided to strip the sensor into its basic parts, Magnet, steel mount and sensor head.
I inspected each component with more detail than what I did at the start of the whole process and did notice a few more metal particles all around,
I found that the magnet had crack in it as well, so I stripped the newly bought sensor and swopped the magnets and cleaned everything.

Remember that when reinstalling the sensor, you need to space the sensor head as close as possible to the gear teeth that it needs to read, somewhere between 12 - 15 thou' ( 0.012" - 0.015" ),

Here's a school of hard knock's tip, even thou you might be tempted to grab onto the rubber moulding to grip the oil covered wires better when massaging it into place, DON'T, the wire seems to go hard after a few years, and the wire coating cracks and break, exposing the inner wire where it meets the rubber moulding...(insert more swear words here), I only noticed this once the wires were back in place....(insert more swear words here). so strip it all out again, clean the rubber moulding and the wires and used some gasket maker to seal it all up before reinstalling again....

at this stage, taking photos were the last thing on my mind, so sorry for not having any photos for backing up the detail in the post

Once the reinstall was done, I redid the tests, all passed,
then tried to start it and it fired up first time.
Took it for a test ride and all seemed fine,
intentionally restarting the bike 20 times and it fired up each time as expected

In summary,
bike died and wouldn't start
no error codes
drained fuel
swopped fuel filter
held starter button down for 20s as the normal auto start time is too short.( some errors only show after 3-5s of malfunctioning sensor)
C12 FI came up, this only comes up if ECU does not hear from the CKP sensor for 3-5s, auto start is only 2s long...
Tested sensor as per manual and noticed ground conductivity on the wires so quickly wiped the sensor head ( this is were the first mistake was make )
it must be properly cleaned and not just wiped, my theory is that any metal particles will disrupt the magnetic field, and not just metal particles on the head of the sensor, mine had a lot of metal particles in all the nooks and small gaps
noticed a crack in the magnet (no sure if this was me or if this there all a long)
replaced magnet
Bike run fine again.
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