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Discussion Starter #1
Has anyone ever gotten a C24 or C25 code and if so what did you trace the problem to?

Robins bike started flashing both those codes today and it was running with reduced power.

The manual indicates it is some kind of problem with the ignition system probably in the coils. We adjusted the valves last weekend. We test road it for a couple of miles then and it was running fine. It also ran fine when we loaded it on the trailer so she could take it home and when she unloaded it from the trailer at her house. This morning she started it to meet up for a ride and FI appeared and when she checked the codes it was alternately showing the C24 and C25 codes. The only things we touched in the ignition system when adjusting the valves were the coils and spark plugs. We installed new plugs when we put it back together and of course the coils had to come off to remove the plugs and valve cover.

Inspection of all the wires and connectors did not turn up any issues. We went through the test procedures in the manual testing everything we could. Resistance test on the coils indicate they are good. We were unable to test peak voltage because neither of us have a peak voltage adapter for our multimeter. We got another set of plugs and installed them on the chance that one of those we installed last weekend was bad but that made no difference. Resistance test on the CKP sensor was also in spec. Again we could not test peak voltage supplied by it to the ECM as we lack the adapter.

Robin has ordered a peak voltage adapter but it will be a few days before it comes in. In the meantime I though maybe someone might have run into this issue and could advise on what fixed it.
 

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The manual says that C24 or C25 indicates a problem with the ignition signal and I quote verbatim: "Crankshaft position sensor (pick-up coil) signal is produced but signal from ignition coil is interrupted continuous by 4 times or more. In this case, the code C24 or C25 is indicated. Ignition coil, wiring/coupler connection, power supply from the battery." (Using the Occam's Razor principal I would go for the battery connections first).
 

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Discussion Starter #3
Thanks for the reply. Yes we saw that and we checked the connections at the battery and also the plugs where the battery leads connect to the wiring harness. Since there have been reports of those plugs melting I was hopeful it would be something as simple as changing out the plugs. No such luck. All the battery connections and plugs were clean tight and undamaged.
 

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[/QUOTE] and of course the coils had to come off to remove the plugs and valve cover. [/QUOTE]

I know that you say you have checked this area but I suggest you check it again. Logic tells me that that is the only other area that could be at fault after the battery check (which you say is ok). The bike was ok before, so this is a simple fault. I wouldn't get side-tracked with peak voltages and such. If is running with reduced power that to me suggests it may be running on one pot. Disconnect the plugs in turn to isolate the faulty cylinder and re-check the coil connection on that one.
 

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I'm sure you checked this, but I wonder if the engine has lost its ground (earth for UK friends) connection.
This would come under 'battery check' which he says is ok. :)
 

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If Buffalo is stomped, like I would have a clue. Right.
Agree, Buffalo stumped on a 650 Burgman problem that has to be a first. ;)
 

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Discussion Starter #9
I know that you say you have checked this area but I suggest you check it again. Logic tells me that that is the only other area that could be at fault after the battery check (which you say is ok). The bike was ok before, so this is a simple fault. I wouldn't get side-tracked with peak voltages and such. If is running with reduced power that to me suggests it may be running on one pot. Disconnect the plugs in turn to isolate the faulty cylinder and re-check the coil connection on that one.
We also did that. It appears it is running on both cylinders just not very well. Unhooking them one at a time you can tell it is running on only the other cylinder. That would be born out by it getting both the C24 and C25 codes. One says that the ECM is not getting a continuous signal from the left coil and the other says it is not getting a continuous signal from the right coil. We ruled out everything else we could think of and that is why we got out the multimeter and started running the test sequence specified in the manual for these codes.
 

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Discussion Starter #10
Agree, Buffalo stumped on a 650 Burgman problem that has to be a first. ;)
Wish I could claim it's the first time. :)

I'm confident we will figure it out, not going to take any bets on how long it will be before we do so ;)
 

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We also did that. It appears it is running on both cylinders just not very well. Unhooking them one at a time you can tell it is running on only the other cylinder. That would be born out by it getting both the C24 and C25 codes. One says that the ECM is not getting a continuous signal from the left coil and the other says it is not getting a continuous signal from the right coil. We ruled out everything else we could think of and that is why we got out the multimeter and started running the test sequence specified in the manual for these codes.
Ok. I still think it's a simple fault though. I would next check the voltage on the o/w wire at the ECU with the engine running. If it fluctuates I would then go for the side-stand relay first, then the ignition switch. Let us know. :)
 

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I seem to recall a vague memory about getting something switched when reconnecting the spark plugs/coils and having problems with the engine. Then again it might just another flashback.
 

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Discussion Starter #13
Well we finally found the problem and got it running right. We went through the whole ignition system and the whole battery/charging system looking for any kind of electrical issue. We could find nothing that was amiss anywhere. That left us with the assumption that it must be something mechanical.

Since the last thing we did was the valve adjustment we pulled the valve covers and started looking for problems there. When we went to set the engine to top dead center to check the valve clearance we found the cams were not in alignment with the crank. They were one tooth out. We corrected that and rechecked the clearances to ensure they were in spec then put it back together and fired it up. Ran like a top. So now we know that if the cams are a little out of time the bike will run but you could get the C24/C25 code indicating a problem with the coils not firing.

As for how the cams got that way we are at a loss. When we put it together the first time both Robin and I double checked the alignment and confirmed it was right. The bike fired up and ran just fine for a short test ride of about a mile and when we loaded it on the trailer and when Robin unloaded it from the trailer. They must have been in time then. It didn't act up until Robin fired it up to head to the ride meet up last Sunday. It was obvious as soon as she tried to move it that something was wrong and the FI light came on within a few seconds. It's almost like the chain jumped time but when we looked at it there was no evidence that had happened.

Robin did said she heard a little popping noise when it started. And right after that is when it started acting funny. Only thing I can come up with is that the cam chain tensioner did not extend fully out when we released it. The popping sound she heard might have been it extending the rest of the way out. And when it extended out that pulled the chain backward and the cams out of time. Past that I am at a lose.

Anyway it appears to be running just fine now. In addition to a 5 mile test ride she road it the 30 miles from my house to hers and it ran just fine all the way. For now we are saying we have it fixed.
 

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Strange. Are the tensioners supposed to be problematic? I seem to remember something about that.

Someone mentioned a while back that the cam timing diagram in the service manual was 1 tooth off, but I've never changed the shims so I haven't had to worry about it yet.
 

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Discussion Starter #15
There have been a couple of people that have posted about cam tensioners that have failed. However as far as I can tell there is nothing wrong with this one. It seems to be functioning just fine. We did double check it this time to make certain it was completely extended before we did the final check for cam alignment.

I don't think there is anything wrong with the diagram in the manual. I've had the head off my bike a couple of times and always put the cams back in exactly like the manual shows. I've also did several shim adjustments on 3 different 650s and they also went back together by the manual.

That's part of what's got me a bit baffled here. Two of use were working on it and it was Robin's first time to do a shim change so I was showing her how to do it and we were both checking each step against the manual. The way we aligned it the first time was exactly as we did it the second time. All the marks were in the same place and the count on the pins on the chain were the same. It's not really a complicated procedure.
 

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Looks like the tensioner push-rod was stuck in the "up" position. The noise you heard would probably it snapping back to where it should be but by then the chain had moved everything on by a tooth or two.
 

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We all hope you never stop riding and wrenching your 650 Buffalo. Thanks again for being such a great resource.

Amen to that !!!!!!!!!

TheReaper!
 

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Discussion Starter #19
One good think about this exercise is that I have now been through all the manual procedures for trouble shooting the ignition system. And now that Robin has bought the Peak Voltage Adapter if the need to do that arises again I will have the knowledge and access to the tool to do it.
 

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Discussion Starter #20
Looks like the tensioner push-rod was stuck in the "up" position. The noise you heard would probably it snapping back to where it should be but by then the chain had moved everything on by a tooth or two.
It did extend when we pulled the special tool that locks it out but I'm thinking it did not go all the way out. That's the only thing I can come up with anyway.
 
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