Author Topic: headlight issue 76 750 f (Read 1289 times)

MasterChief750 · « **on:** April 14, 2011, 09:21:53 AM »

Buddy just got a f and the headlight does not work at all. No the bulb is not burned out no the wiring is fine. It has power but doesn't turn on. Its only reading 11.5 v but in my mind it should still light up. Tried 3 different bulbs with no luck. Tried the light harness off my bike too. Nothing. What the heck is going on has anyone experienced this and have a fix for it.

Gordon · « **Reply #1 on:** April 14, 2011, 09:34:02 AM »

If you're getting power to the headlight plug, then it's the bulb.

MasterChief750 · « **Reply #2 on:** April 14, 2011, 10:32:45 AM »

The bulb works fine on my bike. We have put 3 different bulbs on the bike. None of them work in his but work fine in my bike.

DarcyCB400F · « **Reply #3 on:** April 14, 2011, 10:42:20 AM »

How did you check for power? Assuming you used a test light or ohmmeter, where did you ground it? Perhaps it's a bad ground wire for the bulb?? Did you use the ground wire for the bulb when testing or did you use the headlight bucket or frame?

The starter switch is a common problem... headlight power runs thru it... is this perhaps your issue also?? Just a thought...

bollingball · « **Reply #4 on:** April 14, 2011, 10:42:28 AM »

Then you don't have ground.

TwoTired · « **Reply #5 on:** April 14, 2011, 10:46:01 AM »

No difference high or low position?
Have you checked the green path between headlight plug and battery NEG?

Essentially, if there is potential at the plug (voltage) and the headlight completes the circuit path, then current MUST flow. Electricity breaks no rules, so you've clearly overlooked something.

Cheers,

MasterChief750 · « **Reply #6 on:** April 14, 2011, 05:52:38 PM »

i have to be. no difference between hi or low. when you say check the ground path what do you mean

TwoTired · « **Reply #7 on:** April 14, 2011, 05:58:12 PM »

Quote from: masterchief1112 on April 14, 2011, 05:52:38 PM

i have to be. no difference between hi or low. when you say check the ground path what do you mean

Quote from: TwoTired on April 14, 2011, 10:46:01 AM

Have you checked the green path between headlight plug and battery NEG?

DarcyCB400F · « **Reply #8 on:** April 14, 2011, 06:30:18 PM »

Where did you ground your tester?? If it wasn't the HL socket you prolly have a bad ground in the HL socket and green ground wire...

MasterChief750 · « **Reply #9 on:** April 14, 2011, 06:55:29 PM »

used the hl socket. will dive deeper into this soon

splitt · « **Reply #10 on:** April 14, 2011, 07:43:05 PM »

Where is the headlight ground point? Is it grounded at the headlight bucket, or does the ground run back to either the engine/frame ground or negative battery terminal?

MasterChief750 · « **Reply #11 on:** April 17, 2011, 10:20:14 AM »

i will have to look at the wiring diagram

TwoTired · « **Reply #12 on:** April 17, 2011, 12:07:50 PM »

Quote from: splitt on April 14, 2011, 07:43:05 PM

Where is the headlight ground point? Is it grounded at the headlight bucket, or does the ground run back to either the engine/frame ground or negative battery terminal?

The green wire distribution of the main wire harness. Headlight bucket is not a reliable ground unless there is an positive attachment to the main wire harness.

The main harness greens all connect to the frame at some point. I'm not sure the physical location, though. I would think it wouldn't be far from the engine mounts or the battery to frame NEG connection point.

Cheers,

78 k550 · « **Reply #13 on:** April 17, 2011, 12:33:01 PM »

make sure the green ground wire is plugged in.

Paul

MasterChief750 · « **Reply #14 on:** April 17, 2011, 02:37:28 PM »

the 750 harness ground is at the coils. further testing will follow. it sure is perplexing me

Gaither · « **Reply #15 on:** April 17, 2011, 07:00:53 PM »

FWIW

I had this trouble with the 550 - also, the left front turn sig wouldn't work. This the morning after a night ride the night before with all lights OK.

I ran a "Popwood Ground" (after being told to do so on this Forum) and that corrected both problems. 'Haven't had the problem again.

Just a FWIW.

MasterChief750 · « **Reply #16 on:** April 18, 2011, 05:38:27 AM »

so you ran a ground straight from the HL to the battery?

bollingball · « **Reply #17 on:** April 18, 2011, 06:00:16 AM »

You can run it to the coil mounting bolt should all ready be a ground wire there. While you are at it tie all ground wires in the bucket together with a new pigtail long enough to reach the coil I even solder a grd. wire to the turn sig.bulb socket front and rear. In the bucket I put a wire nut on all the grd. then a ty-wrap on the wires close to the wire nut then remove wire-nut and solder and shrink wrap The wire-nut is just used to twist them togeher good and tight.

TwoTired · « **Reply #18 on:** April 18, 2011, 10:13:45 AM »

Wire nuts are pretty reliable in house wiring. But, houses don't regularly suffer from frequent mechanical shock and vibration.

Further, wire nuts are not gas tight. All the atmospheric impurities and humidity can still get inside and corrode the connections. Copper oxidizes fairly quickly with atmospheric exposure. The oxidation isn't conductive.
Honda used plated connectors to extend electrical integrity. But, even that plating doesn't withstand forever. Who wants to pay for gold plating?

Cheers,

bollingball · « **Reply #19 on:** April 18, 2011, 10:51:58 AM »

TT That is why I said to take it off and solder and shrink wrap. The wire nut is temporary.I just use them to get the wires twisted together good don't need them for two or three wires but there is going to be five or six grd. connection in that bucket and not a lot of room. If you use the ty-wrap when you take off the wire nut they won't come apart when you go to solder them.

. I wasn't sure who you were writing to.

TwoTired · « **Reply #20 on:** April 18, 2011, 11:14:11 AM »

I'm just throwing out information. It's up to the reader apply or reject it.

Cheers,

bollingball · « **Reply #21 on:** April 18, 2011, 11:24:16 AM »

OK I do agree with not using them on bikes I think just electrical tape is even worst.I don't know if the way I do it is called a popwood ground I did a search and got some different answers.TT do you know what it is and how it got the name?

TwoTired · « **Reply #22 on:** April 18, 2011, 11:41:03 AM »

Well, I don't want to hurt your feelings. $:-\$

I'm left with the question of why the original wiring on the Honda worked so badly as to need replacing/rerouting after 30 years of use?

I'd rather fix what is broken than change a workable design, without knowing why the "workable design" failed.

Yes, I know. I'm odd that way. I'd probably look at it differently in a post apocalyptic world where proper parts are unobtainium.

Cheers,

dune · « **Reply #23 on:** April 18, 2011, 11:52:39 AM »

are your speedo and tacho lights 'ON' when you are trying the headlight? if not then its a common ground issue.

as pointed out all opf the'GREEN' goes to chassis ground at the coil. usually its the aft coil mount location where the Grren wire goes to chassis....

somewhere within the headlight one or several of the GREEN connections are faulty or come loose or as mentioned atmosphere has gotten in etc...

IF your tacho and speedo backlights are in fact ON then the problem is isolated to the HL alone... and it could be one or both of the GREEN wires that tie themselves to the bolts / nuts that physically mount the HL in place and on its own relative angle... these typically rust out and loose connection... you can alternatively try running a ground from there to chassis somewhere and try this with a long piece of wire just for kicks and make sure this is the issue - then going about making it clean or finding the actual culprit and replace it... or clean it up.. .etc.

best of luck . electrical grmelins...... they'll get ya!

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Author Topic: headlight issue 76 750 f (Read 1289 times)

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