Author Topic: Can clutch adjust=no neutral light?! (Read 13689 times)

theofam · « **on:** April 15, 2011, 02:29:26 PM »

Got my clutch adjusted inside the clutch cover at the nut/flat-tip bolt. Turned the ignition on and no more neutral light?!

Is there any way a mechanical clutch adjustment can impact the neutral switch? Beyond perplexed . . .

theofam · « **Reply #1 on:** April 15, 2011, 02:40:00 PM »

Nope, the voltmeter shows 12.36V off the bulb's wire, 12.3V at the neutral switch, and the diode is working for the clutch safety switch. Ideas??

OneWheelDrive · « **Reply #2 on:** April 15, 2011, 02:43:46 PM »

Have you cracked the shifter cover to see if the metal tang (neutral light sensor) is making contact with the shifter drum? It's a pretty simple mechanical connection that may just need to be cleaned.

theofam · « **Reply #3 on:** April 15, 2011, 03:00:06 PM »

OneWheelDrive, too bad I'm not near you - I'd buy you a big beer!

I couldn't find anything in the Honda or Clymers manuals showing anything like you just described. I've not taken off the shift cover, but it sounds like that's next on my list! If it works, I'll be one step closer to riding the Relay in early May!

OneWheelDrive · « **Reply #4 on:** April 15, 2011, 03:03:56 PM »

MMMM beer

rklystron · « **Reply #5 on:** April 15, 2011, 03:05:29 PM »

Is this on a 750 or what?

Duanob · « **Reply #6 on:** April 15, 2011, 03:06:44 PM »

You say you're getting power to the bulb wires and no nuetral light? Like Rotortiller sez:

"maybe it's the bulb?"

rklystron · « **Reply #7 on:** April 15, 2011, 03:11:47 PM »

Simple test for a 750. Turn on the key and ground out the center of the neutral switch on the bottom right side of the crankcase. If you do and the switch comes on...Its the switch. If not more than likely the bulb or a connection somewhere.

theofam · « **Reply #8 on:** April 15, 2011, 03:23:48 PM »

Quote from: rklystron on April 15, 2011, 03:11:47 PM

Simple test for a 750. Turn on the key and ground out the center of the neutral switch on the bottom right side of the crankcase. If you do and the switch comes on...Its the switch. If not more than likely the bulb or a connection somewhere.

I want to understand what you're saying. There is a philips head screw that secures the light green/red wire to the neutral switch. Do I strip ends of a wire and touch the wire to both the screw and the engine case? If the neutral light illuminates, it's a bad switch? Just want to make sure. Thanks!

rklystron · « **Reply #9 on:** April 15, 2011, 03:43:03 PM »

Turn on the key. Use a jumper wire and ground the phillips screw to ground. If the light comes on the Something is wrong with the switch. If not Bulb, a wire connection or diode is bad.

rklystron · « **Reply #10 on:** April 15, 2011, 03:44:35 PM »

Early bikes do not have this diode. What model or year is yours?

theofam · « **Reply #11 on:** April 15, 2011, 03:47:49 PM »

Mine is a '78 750K. Thanks for the info, I'll try it!

I was trying to get the gear cover off and shattered my POS impact driver bit. Note to self, no more tools from AutoZone!

rklystron · « **Reply #12 on:** April 15, 2011, 03:49:19 PM »

Wow that sucks. You know what... you will not be able to see anything from inside that cover anyway as far as this problem is concerned.

rklystron · « **Reply #13 on:** April 15, 2011, 03:51:20 PM »

Jumper that bugger...lets see what happens.

rklystron · « **Reply #14 on:** April 15, 2011, 03:52:58 PM »

You might be looking in the wrong place. This will tell you if you are on the right track.

theofam · « **Reply #15 on:** April 15, 2011, 04:29:10 PM »

Philips screw to ground and, drum roll please, no light.

So, bulb, connection or diode.

The diode is working for the clutch safety wire that goes in the other side of it. Is it possible the neutral switch side is bad? Any way to test a two-prong diode with a multimeter?

If I hook the positive side of a voltmeter to the wire coming from the bulb/idiot light and the negative to ground, it shows 12.36V. Doesn't this mean the bulb is good? If not, I can just swap it with the good oil pressure indicator bulb to verify.

Otherwise, I guess I could pull the wiring harness off, unwrap it, and start checking . . . that sounds about as fun as a root canal.

Speaking of root canals, I've gotta take my 11-year-old daughter and four of her friends to dinner and a movie. So, I'm going dark for awhile.

Thanks for all your help!

Oddjob · « **Reply #16 on:** April 15, 2011, 04:42:30 PM »

Another possibility for you. If there is voltage from the bulb wire then the bulb is fine, the circuit works by a constant feed of 12v to the bulb, it doesn't light until the switch on the end of the selector drum grounds it. So you should have 12v at least on both sides of the bulb, that's if the bulbs not blown of course. The wire run down the harness to the large block connector behind the sidepanel where the sub harness from the left hand casing connects to it. The connections in these block connectors do corrode over time, simple test would be to pull this connector apart and check the terminals on each block, you could even get a wire, shove it down the back of the neutral wire, green/red IIRC, on the main looms block and short this to one of the engine bolts. If the light comes on then it's either a break in the sub wiring harness or the conenctors have corroded in the block connector.

rklystron · « **Reply #17 on:** April 15, 2011, 04:48:32 PM »

Swap the bulb with the oil pressure bulb. Yes you can check the diode. Put your meter on OHMS. In one direction it will read open. (No continuity). In the other direction very close to 0 OHMS. If this is the case diode good. Time to start checking wiring. In order to do this you will need a wiring diagram for you bike. It's actually pretty easy. Point a to point b kind of thing. What bike do you have. I can send you a diagram if you do not have one. Also it would be fun to walk you through this, you will be amazed at how easy it really is.

DarcyCB400F · « **Reply #18 on:** April 15, 2011, 05:07:50 PM »

Quote from: theofam on April 15, 2011, 02:29:26 PM

Got my clutch adjusted inside the clutch cover at the nut/flat-tip bolt. Turned the ignition on and no more neutral light?!

Is there any way a mechanical clutch adjustment can impact the neutral switch? Beyond perplexed . . .

Just my 2 cents worth here but I find it really odd that the bulb quit working after you adjusted your clutch... I think perhaps this is important...

2 cents spent

rklystron · « **Reply #19 on:** April 15, 2011, 05:26:20 PM »

The only thing I can say is Sh$T happens. The adjustment of the clutch has no bearing on the neutral light being on or off. One is mechanical and the other electric. Now if the bike did not turn over (starter switch) you may have something in your idea. If the bike is not in neutral and the clutch lever is not engaged the bike starter circuit is not enabled. (Smart Honda engineers). This is only for the later bikes K5 and beyond I believe. I would have to look at the wiring diagrams to be sure. If Theofam cheated the neutral switch with a jumper to ground and the Ignition switch was on and everything is good, Diode connections and bulb, the light will come on. That's how it works. If that did not work (Bulb did not come on) either the bulb is bad or a connection to the circuit is bad. Ground coming for the switch or the Black wire from the bulb to HOT. The is nothing else in this circuit. My 2 cents.

theofam · « **Reply #20 on:** April 15, 2011, 06:23:21 PM »

You guys are awesome. Thanks for the ideas - I've got work to do!

Sshhhh, the movie is starting!

rklystron · « **Reply #21 on:** April 15, 2011, 06:27:30 PM »

Enjoy the movie!

phil71 · « **Reply #22 on:** April 16, 2011, 11:15:08 AM »

is this thread really this long before even trying to swap the light bulb?

Jerry Rxman Griffin aka MuthaF'er · « **Reply #23 on:** April 16, 2011, 12:09:43 PM »

Somebody get that boy another switch to try!

bollingball · « **Reply #24 on:** April 16, 2011, 01:07:20 PM »

Is it me or do you just not want to tell us WHAT BIKE IS IT.

theofam · « **Reply #25 on:** April 17, 2011, 10:53:30 AM »

BB, reply #12 - '78 750K.

Phil71, I figured replacing the bulb was unnecessary since the voltmeter already showed 12.3V on the wire coming from the bulb. Voltage from bulb=good bulb. To your point, I didn't want us blowing any more time on this in case my understanding was incorrect. I swapped the good oil pressure bulb with the existing neutral light bulb and still, no light. I'm trying to avoid the costly process of simply swapping components until it works. I'd rather use my multimeter to tell me where the problem is.

Based on input from you guys, I'm pretty sure at this point it's either the diode or a loose/bad connection in the harness. So, I'll be able to jump on this Tuesday. I'll first test the diode. If it's good, I'll start unwrapping the harness to see where that light green/red wire is problematic.

Take care!

DarcyCB400F · « **Reply #26 on:** April 17, 2011, 11:05:04 AM »

I am curious if you have taken the bike for a ride since adjusting the clutch? Can you find neutral without the light? Does if flash when you shift to second from 1st?

Oddjob · « **Reply #27 on:** April 17, 2011, 01:49:03 PM »

Damn I should have thought of this before but it's been a few years since I've had to repair one of these and it slipped my mind.

Grounding out the phillips screw on the end of the selector drum may not highlight the problem. The neutral light switch works by grounding the neutral wire through the switch and onto the oval piece screwed onto the selector drum. This small oval piece is made of a sort of bakolite or hard plastic, it has a brass strip running through it and around the screw hole, the strip is right on the upper edge of the oval section. It's this strip which connects with the neutral light switch, as soon as you select neutral the strip connects, however the inside of the chain case gets rather grubby/greasy and sometimes the strip gets covered in gunk OR the very tip of the neutral switch where it would connect to the strip breaks off or bends away. As the switch can no longer ground you get no light.
Pull off the green/red wire from the switch, it should be a male connector and just push into the switch so should come off very easily. Hold this wire against the engine and if it lights the switch or strip need cleaning or some slight attention. Extremely easy to do this so I'd do this first as I'm 99% sure the problem lies there.

theofam · « **Reply #28 on:** April 28, 2011, 03:15:59 PM »

Darcy, I can't ride it yet. Still piecing it together.

Oddball, I had checked the switch and had power to it, so I decided it was the diode or wiring harness. The diode was OK, so I took off the wiring harness last night.

There was a spot on the harness that was chafed, but I unwrapped the entire harness to check the entire neutral light wiring. The wire looked great front to back, but I decided to cut and solder the wire where the wrap had been chafed. That fixed it! I have a neutral light again!!

So, it was a bad wire to the headlight bucket . . . CASE CLOSED . . . WOOHOO!

DarcyCB400F · « **Reply #29 on:** April 28, 2011, 04:09:15 PM »

Congratulations! wiring gremlins are always nasty business!

Toxic · « **Reply #30 on:** April 29, 2011, 01:27:31 PM »

Quote from: rklystron on April 15, 2011, 03:11:47 PM

Simple test for a 750. Turn on the key and ground out the center of the neutral switch on the bottom right side of the crankcase. If you do and the switch comes on...Its the switch. If not more than likely the bulb or a connection somewhere.

Dang, thanks man now I know why my neutral light doesn't work. Next time I have the pipes off I will change it out. I can't see it being done with the pipes on.

Bill 350F · « **Reply #31 on:** May 01, 2011, 08:18:15 AM »

I'm having a similar problem with a '72 CB350F. The bulb works. When I removed the sensor it was pretty clean. I wiped off a little gunk, reinstalled and still nothing. Attach the volt meter to the wire and ground, bike is in neutral, ignition switch on, no juice. How is this bulb powered? I've been looking at this wiring diagram and it connects to an emergency switch. Huh? Where's that?
(I've been looking at the schematic on the Old Man Honda page for the 350F, sorry it won't let me post a link)

Bill 350F · « **Reply #32 on:** May 02, 2011, 09:51:34 AM »

I'm going to have another go at it today. Any ideas?

Oddjob · « **Reply #33 on:** May 03, 2011, 02:29:34 PM »

Quote from: Bill 350F on May 01, 2011, 08:18:15 AM

I'm having a similar problem with a '72 CB350F. The bulb works. When I removed the sensor it was pretty clean. I wiped off a little gunk, reinstalled and still nothing. Attach the volt meter to the wire and ground, bike is in neutral, ignition switch on, no juice. How is this bulb powered? I've been looking at this wiring diagram and it connects to an emergency switch. Huh? Where's that?
(I've been looking at the schematic on the Old Man Honda page for the 350F, sorry it won't let me post a link)

Bulb isn't powered from the emergency switch, that's the on/off switch on the R/H handlebar switch, the red looking thing on the top, the diagram isn't clear but the neutral light is powered from the black wire, on Hondas of this time period black was the common power source, so the bulb is powered off a switchable 12v source, it won't light until the bulb is earthed, that's what the neutral light switch does. Remove the wire from the neutral light switch and hold it against the engine, the bulb should light, if it doesn't then the bulb has either blown, it has no power or there is a break in the green/red wire somewhere in the loom.

Bill 350F · « **Reply #34 on:** May 07, 2011, 10:09:56 AM »

Thanks. I actually did figure it out. I unwrapped a good portion of the harness, inspected the wires and found nothing. I went back to the bulb and took apart the housing and sure enough the solder on the black wire had broken off but the wire was still inside so by appearances it looked good. fired up the soldering iron and fixed it.

I guess I still don't understand the difference between the front stop switch and the emergency switch. I thought maybe there was some switch that trips if the bike falls over or something. Anyways it works now thanks again!

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Author Topic: Can clutch adjust=no neutral light?! (Read 13689 times)

bollingball