I've took a couple of photos from my manual, it's the sp400 manual, but in all intent and purposes it is the same as the dr400 which is what i have (which is a week or so away from being started, so i can't confirm if i have any charging issues yet)



as you can see the resistor is in the rectified circuit and is switched in and out as you turn the lights on. the lights (except for the tail light which needs to be dc for parking) is in the ac line and follows what i was talking about earlier whereby the resister comes out of circuit when the lights are on.



however, if you look at the wiring diagram in the same manual, it seems to contradict itself. the light circuit comes off the magneto in the pink wire. it goes up the frame to the connector plug that meets with you handlebar switch gear lead. from there it changes colour to yellow and red and runs to you light on/off switch on the bars and just stays there until the lights are switch on.
when the lights are switched on, the voltage comes back down on the green wire which goes to the voltage regulator (resistor) under the seat, and also to the speedo/tacho lights. at the same time there is a link in the switch gear to the hi/low beam switch. from there it either comes out on white or yellow for low/high beam.

the tail light and brake light are on the rectified dc circuit. this comes off the magneto on the white/blue wire and runs to the same plug as the light circuit where it changes colour to yellow/red in the bar light switch. now here is where i don't get it. it stays there until the lights are turned on. what i mean is that the battery only gets charged when the lights are on, which is fine if you are in a scandinavian winter, not so fine if you are in a scandinavian summer where the contant use of indicators and breaking is going to flatten what looks like a total loss battey system.
from the battery, the power comes off on the red lead to the ignition switch, where it comes out as orange when the ignition is on. with t-offs for the brake light switches, flasher relay and horn, it also goes up the bar switch gear again and sits there until the lights are turned on,- where it comes out on the brown wire - to brown/yellow and back to brown again and off to the tail light.
at the same time as the lights are turned on, the yellow/white in the switch gear (originally the white/blue from the magneto) is swithched in and comes out on the white/red wire which runs straight to the rectifier without passing go or collecting £200, where it comes out as a rectified dc voltage and feeds back into the red battery/ignition wire.

i'll post the tests below as they are written in the manual. as i said earlier, i'm a couple of weeks away from knowing wether i'll have any issues with my lights.i did have my unmolested wiring loom and switch gear at work and 'belled' the wires out and they do match the loom posted.

hope this helps
Richard.

cloggy - yes frogeye is our best chance of understanding all this. My last post, however, was moving on to a different issue - what makes the headlamp bulb blow when all electrical components are up to standard Suzuki spec. There must be riders out there with standard set up who never have electrical problems so...LETS HEAR FROM YOU - even if only to convince us that there could be light at the end of the tunnel!
walesy - yes, I'll check. I am in the middle of rewiring (more in hope than expectation).
frogeye - Richard,you seem to enjoy wiring diagrams! At first, I was puzzled by "the voltage comes back down the green wire to the voltage regulator..." (BTW I think you mean grey not green - Gr=grey, G=green). However, I can see that your picture is diagram E28 which is for Canada (&USA?). UK diagram is E-02. However, this is for SP400. Perhaps DR400 is same for Canada & UK. I mention this so that SP owners don't look for a regulator on the end of a grey wire. Instead, their magneto resistor is fed by the white/blue from the magneto when the lights are off, as you have shown above.

In any event, I think I can answer "the Scandinavian question"! Using the diagram that you posted, the route is.. magneto - white/blue - connector - yellow/white - lighting switch - white/red. Note that - according to the little chart for the lighting switch - current goes along white/red to the rectifier (then to battery for charging) BOTH when lights are on and when off, so you can ride all year round in Scandinavia with indicators and brake light working! Having said all this, I have zero electrical knowledge. I am just trying to read the diagram as I would an OS map. So, if I've got it all wrong, please shoot me down, I can take it! Mike

sorry, gr is grey, not green. it was 5:30 in the morning and i'd been at work all night

it seem half the photos got chopped off so i'll post the direct links

http://i153.photobucket.com/albums/s201 ... C_0031.jpg


http://i153.photobucket.com/albums/s201 ... C_0032.jpg

http://i153.photobucket.com/albums/s201 ... C_0030.jpg

http://i153.photobucket.com/albums/s201 ... C_0029.jpg


with regard to the charging,mike, as you say, the out put from the magneto comes along the white/blue to yellow/white. but it just sits there until the light switch is in the on position, when it then goes out the red/white wire to the rectifier. using the full size diagram, i can't see any other way the battery gets any charge. but as you can see, it contradicts the smaller charging diagram.

there are two open terminals showing just above the magneto. now if they were joined(but i think they are both female terminals) that would send power down the green/white wire and feed the red/white and charge the battery with the lights off.

i know it's the us spec diagram, but as i mentioned, i traced all the wires of my loom out and they match up. i'll double check tonight at work, but after an hour looking at wiring diagrams, my eyes feel like a cirtain blondie album (for those of you old enough )

catch you later.

er..oh..you are of course right, Richard (for one wild moment I had thought I was learning to interpret a wiring diagram!)
Of course, with regard to your point about the two open terminals, these ARE joined in the SP370 (when the lights are off) because thats where the mag resistor is located. Both the open terminals are female as you suggested and this would be correct because the white/blue and green/white coming out of the std Suzuki mag resistor (which I have) are both male terminals). I assume that the resistor is removed from the DR400 because you have the separate regulator on the end of the grey wire. So, we are back to your point...how is the battery charged when the lights are off! Suddenly, the SP370 seems a good system (in comparison)! Could it be simply that Suzuki made a mistake on the E28 wiring diagram? If they were actually turning out bikes without lights-off charging, you'd have thought it would have been brought to their attention and that they would have produced a modification.

The first person on this forum to get to bottom of this (I don't think it'll be me) will have a great sense of satisfaction!

Mike

mike, your comment about the 370 having the resistor across then two oprn terminals makes things a lot more clear to me. can you tel me if the 370 has the regulator at the end of the green, er i mean grey wire?

i'll take all my harness and compnents to work tonight and see if i can get to the bottom of it.
cheers
richard

After my "yellow/white in the light switch" faux pas, I hesitate add more but...... I looked at my Clymer manual for SP/DR 370/400 and the wiring diagrams are interesting......No doubt Clymer is interested only in the USA models so perhaps there is a parallel with your DR400... For the USA SP370C, there are still the two open terminals and no obvious way to charge the battery when the lights are off. The USA SP370N has both regulator AND magneto resistor so the open terminals are no longer open when the lights are off! So, perhaps your bike simply needs a Suzuki magneto resistor as well as the regulator despite what the diagram indicates! I don't know how to load pictures from a scanner on to this site but if you wish to PM me with your personal e-mail address, I'll send you a scan of the diagrams.
Mike.
PS If I have again got it wrong, I promise to withdraw gracefully from this discussion!

PPS just seen your latest. Got to go, will be back in 1 hour!

Richard, re yours of 5.41pm.
No, thats the difference in a UK SP370 - there is no regulator. The grey wire ends in an open terminal on the UK SP370. Perhaps there is some inherent weakness in the design and that going to magneto resistor PLUS regulator was Suzuki's belt & braces solution. On the other hand, I have read that there were similar problems on DR350s from the 1990s.
Mike

got your e mail mike, and i've amended my post regarding email address

your uk sp370 diagram makes more sense regarding the smaller charging diagram i posted earlier and to my first post on the problem. my dr 400 is the same as you 370 diagram with the exception that the dr is cdi not points.

the resistor is placed in the diagram just above the magneto, and mine doesn't have the voltage regulator shown on the end of the grey wire.

so to speculate again, the two feeds off the magneto need to reach ground at some point to obtain 6v. if your lights are off, then only the rectified circuit will ground giving you 12v. to combat this, the resistor is switched in circuit to pull the voltage to 6v. this isn't a 'regulator', only a resistor. if the resistor fails open circuit then your battery will not charge when lights are off. if the resistor fails short circuit, then your battery will cook with 12v or the rectifier will blow.

with your lights on, both circuits are grounded, so there is no need for the resistor. however only the headlight and instrument lights are ac, so if they blow or become corroded they wont reach ground, so 12v goes through the remaining charge circuit, this time with the resistor switched out and cooking your battery or blowing the rectifier.

with a damaged rectifier or knackered battery your lights will blow every time they are turned on as there is no ground on the charge circuit so the lighting circuit goes to 12v.

i think what is needed is a belt and braces approach like you said mike.

if you fit one of these
http://cgi.ebay.co.uk/BSA-BANTAM-D1-D3- ... 53db8eb67b

onto the end of that grey wire, as per the usa diagram i posted then i think all areas would be covered.

assuming your battery is ok, and your mag resistor is ok and all terminals are free from corrosion, then if your main beam should blow (possibley due to vibration) then the excess voltage that would appear would be dissipated away preventing voltage surges and damage to the rest of the system.

for info, my resistor reading is 5.6 ohms

the rectifier is 1.5 Mohms one way, open circuit the other.

as has benn posted before, it's a delicate circuit and relies on everything in tip top condition.

does this sound feasible

unfortunately i live in the north east, the otherside of the country.

cheers
Richard.

Richard, thanks, not just feasible but a convincing exposition!
I can see the point "it's a delicate circuit and relies on everything in tip top condition". This is what I am aiming for with my re-wire. As part of this, I'll fit a regulator on the end of the grey wire.

On a point of detail re "however only the headlight and instrument lights are ac, so if they blow or become corroded they wont reach ground, so 12v goes through the remaining charge circuit" - would this happen if, say, the headlight bulb was OK but an instrument light was missing or blown?

Per earlier post, it would be interesting to hear from SP/DR OWNERS WHO NEVER HAVE ELECTRICAL PROBLEMS. Please post now!

Mike

it's been 20 years since i did this at college.

now i don't know what the effect of reducing the current of one of the phases will do (ie. taking each bulb out one at a time) will it proportionatly increase the voltage on one side at the expense of the other?-i don't know.

the way to find out would be to measure the voltage in the light circuit with all lights on (you can use that spare grey termial to hook a volt meter to) then set your engine to high tickover and start by pulling the bulb supplies out and see what hapens to the voltage.

WoW ! What a topic.

I Have read through it all, suffering the same problems with a DR400, and what would be really useful here at the end, would be a final solution.
Seems you guys have been there before and studied it extensively. It's good to find that someone else has experienced all this.

Maybe frogeye could write a summary, and the best fix.
As far as I know, I have the correct wiring loom, and some rusty components, (resistor and diode) disconnected . 6V circuit and battery, but no charging, (obviously, as bits are disconnected).

Should I buy the BSA regulator? what about the resistor and diode on the bike ?

Thanks guys.

My bulbs blowing turned out to be a bust regulator.
I then bought a solid state one from electrex [their website has a bunch of errors re suzuki singles]
I also had an unearthed battery and an unearthed tail/brake light
I'd bought another bike as a rolling chassis and picked up an engine for a fiver.
Once I'd sorted the valves and started it up it blew bulbs on both AC and DC circuits. How is it that the regulated AC circuit also appears to regulate the DC circuit that runs the brake tail and horn?
With just the unearthed battery to be discovered but with a new AC regulator it stopped blowing the DC tail light

Hi all, I have a sp400 that has given no electrical problems at all- luck or what-and still standard. With my last dr400 which needed new loom i split it down into 2 seperate systems, charging and lights, with original regulotor and rectifier. and have had no problems so far. I think the more we read about that`s off when thiss`s on and visa versa it`s bl---y confusing. Suzuki certainely made some technical circuitry with this one. Yamaha didnt have these problems with their dt`s. Which is why i wired my dr like the dt. Works fine. Cheers me deers.Only difference between models on sp400 was the need for a foont sidelight, or city light as they so called it, on the english,finland, swedish and french models which had 2 extra wires to ign switch. ^ wire switches are expensive or hard to come by, fit a 4 wire switch as it dosent need it for an m.o.t..

Nice to know it's not just me! Been wrestling for ages with the 29 year old mess of spaghetti that passes for wiring on the GN400 just trying to work out why it keeps blowing headlight bulbs. All earths are clean and shiny, the battery is less than a year old, the rectumfrier is new, yet still the front bulb has been getting more volts than it can handle - aarrrggghhh!

Yesterday I spliced in a 6v AC Regulator (piggy-backed on the pink wire) from that bastion of old Brit electrics, Paul Goff - Clicky Linky Thing - scroll down a bit for the regulator. First checks with the trusty multimeter are showing 6.5 - 7v maximum, so confidence is high. Fingers crossed.

So you too have found that a regulator on a supposedly separate battery circuit affects the rectifier headlight circuit.