PNW-FZ6

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Hey all, new around here so I hope I'm doing this right!

I recently picked up an '07 FZ6 S2 with ~10k mi., on the test ride and on the way home I didn't notice any issues- the bike ran great. However after doing some slow speed practice in a parking lot on the ride back home the check engine light would come on at around 4k RPM and turn back off at lower RPM's. I've gone out and replicated the problem 3 or 4 times now in the exact same way, it takes ~15min. of riding for the light to start going on and off as I have described.

Of course, the first thing I did was check the diagnostic mode and saw that I had a code 46. I then checked the FSM and noted that the code means that FI system is not receiving normal voltage and that it is probably an issue with the charging system. After scouring the web and reading through these helpful threads:



I went ahead and tested my battery, stator, and RR, with a multimeter and all measurements check out and are within FSM specs (battery fully charged - 12.8V (measured after bike sat overnight), stator resistance within 0.23-0.32 Ohm. range, and RR pins showing 0, 0, 0/~500, ~500, ~500). I also checked all the fuses and connectors, including the ECU connector and nothing is blown, dirty, or corroded. Even the charging voltage is fine on cold start, it settled in the 13.9-14V range and increased up to just above 14V at 5k RPM.

So, everything seemed fine and I went out again to see if I could replicate the issue and measure the charging voltage after the check engine light had been going on and off. When I came back after the light did the 'on at charging RPM, off at non-charging RPM (after ~15min.)' thing while riding, I checked the charging voltage at idle and it read low, 12.6-12.8V and when increasing to 5k RPM it climbed all the way up past 15V. I am guessing the bike reads low at idle to clear off any excess charge from the overcharging?

The only thing I have not checked are the grounds as I can't seem to find any information online or in the FSM I have about where they are (seriously, even doing a ctrl+f in the FSM pdf for "ground" doesn't tell me much - maybe I am blind or dumb but I can't find the ground locations...).

Anyways, does this sounds like a blown regulator, as the internet suggests, to anyone with more experience than me? It seems like once the bike gets up to temp and parts start getting warm after that 15min time period while riding, the regulator stops shunting excess voltage from the stator leading to an overcharging issue that trips the check engine and throws the code 46. I have a new OEM RR and battery on the way already, I am just concerned that maybe something else would have caused the regulator to go bad because the bike only has 10k mi. on it? The only mod on the bike is aftermarket LED turn signals (front and rear) which the PO installed and I don't think would have an effect on the overcharging charging system (right?).

Thanks in advance- any help, advice, opinions, are welcome!
 

Gary in NJ

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Welcome. You’ve done a great job identifying the problem. The diode test you performed checks the rectification of the R/R. There isn’t a bench test for the regulator. Observing output is the only way to determine if it is working properly. Keeping the leads attached to the battery, you could mount the multimeter up by the bars and try to observe the voltage while replicating the problem. It’s probably not necessary because the 12.6-12.8VDC that you saw at idle is an indication that there is zero output from the charging system. If you have a lithium battery the 15 volts that you saw can create an explosion hazard.

Assuming that you’ve checked the connector for a broken or intermittent lead and that you’ve checked the harness for signs of chafing and found nothing, then a replacement r/r is in order.
 

Motogiro

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Yes great job! That sounds like you're on the right track. Make sure your R/R plugs have good integrity.
 

PNW-FZ6

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Thank you both so much for the quick replies.

Welcome. You’ve done a great job identifying the problem. The diode test you performed checks the rectification of the R/R. There isn’t a bench test for the regulator. Observing output is the only way to determine if it is working properly. Keeping the leads attached to the battery, you could mount the multimeter up by the bars and try to observe the voltage while replicating the problem. It’s probably not necessary because the 12.6-12.8VDC that you saw at idle is an indication that there is zero output from the charging system. If you have a lithium battery the 15 volts that you saw can create an explosion hazard.

Assuming that you’ve checked the connector for a broken or intermittent lead and that you’ve checked the harness for signs of chafing and found nothing, then a replacement r/r is in order.

Thanks, I tired to do all I could before posting to confirm my suspicion. There are not any signs of damage to the wiring that I could find. Good to know about the explosion hazard, I figured I shouldn't ride the bike until the problem gets sorted.

Yes great job! That sounds like you're on the right track. Make sure your R/R plugs have good integrity.

Awesome. All the plugs both male and female to the RR, stator, ECU, and the contacts on the battery are all good to go.

Sounds like its a blown regulator then, annoying how you can't test that component by itself, I'll update the thread once I receive and install the new RR and battery hopefully later this week/early next week. Thanks again!
 

PNW-FZ6

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Update:
It's fixed! Parts came in a little later than expected, but I replaced the R/R and battery for good measure. Took the bike out two or three times since working on it to try and replicate the issue after about ~15-20min. of riding and it seems to be all sorted out, no more check engine light going on and off. Was definitely a bad regulator as everything else checked out.
 
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