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Front turn signal is solid on

1K views 8 replies 6 participants last post by  Andrew 
#1 ·
Hi, was wondering if anyone had a lead on what to check out first...

I have a 2000 748 with a MotoDynamic LED tail light and the integrated turn signal.

When I activate the turn signal the rear works as it should but the front OEM signals stay solid lit, they turn off when I cancel the turn signal.

I noticed when I came out from a quick errand the LED tail light was on even though I had turned the ignition off and had the front forks locked. Shortly after my bike started to want to die, it even shut off once while coasting to a red light. It started right back up fine though.

the next instance is that I had to do a push start at the end of the day to make it the last mile home after stoping to eat. when it started from the push the headlights were barley on and the bike was trying to die the whole mile home. It did die last 1/4 mile but was able to pop the clutch since i was already rolling.

I only work about 2 miles from home so I have been keeping it on a tender every night.

What I have checked so far:

Stator puts out 20V at idle and over 55 on revs, connector isn't melted as i replaced them with watertight connectors ( I am wondering if the connectors I used are a problem cause they are rated for 16V DC and 20 Amps)

Regulator passed the diode multimeter test getting .55 on both red wires. I didn't get the OL when I checked the Reverse Bias but i was thinking it's because I have a cheaper meter. It just stayed @ the default value of 1 with no change

Battery passed a test at auto parts store, no bad cells and was at the right specs

Battery DC voltage:
When bike is off: 13.18V
When ignition is on: 13.18v and will go down .01 with the load draining it
When bike is running it seems to hold@ 13.5 or gain a little voltage when reving but not a lot more

Any ideas??
 
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#3 ·
Lets look at this logically, is the rear light always on (even when the bike isn't locked)? Are you sure you hadn't turned the key to the last position after lock which also activates the front and rear parking lights?

Do you have an alarm on the bike? - they are notorious for failing and taking the battery down and just generally causing starting problems.

Notwithstanding, there seems to be an issue, the battery was discharged.

Reading the voltage on an alternator with it disconnected from the regulator rectifier is effectively useless, you will get artificially high values (i.e. 50v) and since there is no load, you will also not be able to see if one of the phases is under performing.

To test an alternator, do the following:

1) Unplug the alternator from the regulator rectifier

2) Set your multi meter to Ohms and check the the resistance between each of the phases, each of the 3 readings should give a reading of zero.

3) Test each phase to earth (or the negative pole of the battery), each of the 3 phases should give a reading of infinity (or open circuit).

If the above is not the case, you have a dud alternator.

Next reconnect the alternator and read the battery voltage. A good battery with no load should read around 12.5 volts. Turn on the ignition and headlights and the voltage should still read above 12 volts, then start the bike and look at the voltage, if it drops below 12 volts with the headlights on or below 11 volts when cranking, I would consider the battery to be be suspect.

With the bike running at around 1500rpm you should be seeing at leat 14 volts on the battery. You can load and unload the alternator by turning on and off the headlights (you may have to pull the fuse to do this) and this should make very little difference to the voltage.

If there is less than about 13 volts present when the engine is running at 1500 rpm then your batter isn't being charged efficiently. At this point you can look to see if there is an issue with the wiring or regulator rectifier.

On the DC side of the regulator rectifier, the voltage should be identical to the reading at the battery, if not, then at then wiring between the battery and regulator rectifier is suspect, common issues are corrosion in the plugs and main fuse causing losses.

If the DC side is good, then check the AC side, under load each of the phases will make about 17 volts again the actual number is not so important but rather that they are all about the same. If there is a phase with low voltage, and the it passes the previous test, then the wiring between the alternator and regulator rectifier may be suspect. If all phases are the same voltage, then the regulator rectifier is the probable suspect.

It is also possible that the charging system and battery are OK and you have a parasitic power drain.

Being a 748, if it is standard, then when turned off, there should be no current drain present. Before I continue, to do the next test, you want a multimeter that will read at least 10 amps and you must understand how to use it or the multimeter it may fail due or blow its fuse due to over current (from the 749 and 999 onwards, they have factory security systems and will therefore always draw limited amount of power from the battery).

To test for parasitic power drain, turn the bike off disconnect the battery and then set your multimeter to read DC current and see if there is any power draw, ideally the reading should be zero. If you have an alarm then some reading is reasonable however this should be less than 0.1 amps.

Assuming the bike is standard any reading is showing a parasitic power drain, if you have any non standard accessories (HID lights, power outlet for a phone charger, handlebar heaters etc), have a look there first by disconnecting them - if there is a drop in power draw then that is the likely culprit.

On the bike itself, only the regulator rectifier is normally directly connected to the battery and occasionally they fail and discharge the battery so if a current reading is present, test the regulator rectifier first by pulling the main fuse or disconnecting the regulator rectifier. If the regulator rectifier passes the test works, then it's a case of pulling the fuses one by one and seeing what results in a power draw reduction.

Good luck,

Andrew...
 
#6 ·
Sorry for the late reply, I didn't get the notifications!

The problem with the front signal lights not flashing was due to the flasher relay not working, it clicks when I plug in the relay but doesn't flash the lights. I just bought it a couple months ago but it rained on the bike the other day while parked and the side fairings off :frown2: I guess the rain took out the flasher.

To test an alternator, do the following:

1) Unplug the alternator from the regulator rectifier

2) Set your multi meter to Ohms and check the the resistance between each of the phases, each of the 3 readings should give a reading of zero.

3) Test each phase to earth (or the negative pole of the battery), each of the 3 phases should give a reading of infinity (or open circuit).

If the above is not the case, you have a dud alternator.
I have a 2 phase alternator, when checking Ohms with meter set to 200, (positive to one lead and ground to the other lead) I get 00.4 on the meter

When checking Ohms to ground I get OL on the meter


Next reconnect the alternator and read the battery voltage. A good battery with no load should read around 12.5 volts. Turn on the ignition and headlights and the voltage should still read above 12 volts, then start the bike and look at the voltage, if it drops below 12 volts with the headlights on or below 11 volts when cranking, I would consider the battery to be be suspect.

With the bike running at around 1500rpm you should be seeing at leat 14 volts on the battery. You can load and unload the alternator by turning on and off the headlights (you may have to pull the fuse to do this) and this should make very little difference to the voltage.

If there is less than about 13 volts present when the engine is running at 1500 rpm then your batter isn't being charged efficiently. At this point you can look to see if there is an issue with the wiring or regulator rectifier.
Battery voltage when bike is off is 12.8V

When key is set to "on" voltage begins going down fairly quickly and then it dips to 11.2 on the crank. It is starting kind of weak in my opinion, kind of like a trickle start, not a crisp crank and fire. Voltage raises to 12.28 when running and only goes to 12.29 when revving or holding down throttle. I don't think my tachometer is accurate, it's kind of jumpy and always seem to be around 6-7k.



On the DC side of the regulator rectifier, the voltage should be identical to the reading at the battery, if not, then at then wiring between the battery and regulator rectifier is suspect, common issues are corrosion in the plugs and main fuse causing losses.
The voltage from the battery to the regulator connector is the same as the battery so those two sets of wires are good.

I disconnected the regulator at the connector that feeds the battery and I got .5 V DC when checking each pair of the green/red wires (there are two pairs). Does this mean the regulator is not converting the AC to DC voltage to recharge the battery?


If the DC side is good, then check the AC side, under load each of the phases will make about 17 volts again the actual number is not so important but rather that they are all about the same. If there is a phase with low voltage, and the it passes the previous test, then the wiring between the alternator and regulator rectifier may be suspect. If all phases are the same voltage, then the regulator rectifier is the probable suspect.
I'm not sure how to check the AC side, I just put the negative lead to one phase and the positive lead to the other phase and I was getting 20V at idle and 55+ on revs.

It is also possible that the charging system and battery are OK and you have a parasitic power drain.

Being a 748, if it is standard, then when turned off, there should be no current drain present. Before I continue, to do the next test, you want a multimeter that will read at least 10 amps and you must understand how to use it or the multimeter it may fail due or blow its fuse due to over current (from the 749 and 999 onwards, they have factory security systems and will therefore always draw limited amount of power from the battery).

To test for parasitic power drain, turn the bike off disconnect the battery and then set your multimeter to read DC current and see if there is any power draw, ideally the reading should be zero. If you have an alarm then some reading is reasonable however this should be less than 0.1 amps.

Assuming the bike is standard any reading is showing a parasitic power drain, if you have any non standard accessories (HID lights, power outlet for a phone charger, handlebar heaters etc), have a look there first by disconnecting them - if there is a drop in power draw then that is the likely culprit.

On the bike itself, only the regulator rectifier is normally directly connected to the battery and occasionally they fail and discharge the battery so if a current reading is present, test the regulator rectifier first by pulling the main fuse or disconnecting the regulator rectifier. If the regulator rectifier passes the test works, then it's a case of pulling the fuses one by one and seeing what results in a power draw reduction.
I disconnected the battery and put my multimeter leads on the positive/necative leads of the bike and don't get a current reading, it stays @ 0.


Any idea?

I think maybe the rectifier since it wasn't putting out any DC Voltage while the bike was running which is why I have to put the bike on the battery tender every night to charge the battery up. Could the rain have taken out my rectifier?
 
#5 ·
Can I ask a stupid question?

Did the bike just suddenly start doing this on it's own, or did it happen along with a change? Had you just installed that aftermarket lighting, or has it always been on the bike?

Do you have stock rear lighting you could try swapping back on?
 
#7 ·
What do you mean, "When key is set to "on" voltage begins going down fairly quickly" ? Some movement over time would be expected with the fuel pump pressurizing the system, your lighting, etc. I certainly wouldn't describe that as "quickly". So, there you are back to Andrew's post about parasitic drain. Also, since as he says, a crap battery can act just like that, have it tested somewhere else or try another battery. It's inadvisable to jump a larger battery to the one in the bike. If you want to try another battery, disconnect the one onboard.
 
#8 ·
Voltage starts at 12.80 and it will go down .01 or .02 V per second until I start the bike due to the headlight being on.

Had the battery tested at auto parts store and it was good with no bad cells.

I'm not getting and parasitic drain across the main Positive/Negative battery connection with battery disconnected.
 
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