Big Red Speedo Light question

[MFW]

Bought a new bike that had a speedo on it. The light only works when i touch the edge of the case when putting it inside the head unit. Once it pops into place with the rubber grommet the light goes out. Seems like a ground issue but I went through and checked all the wires in the harness. Is there something inside the head unit that will ground the light? Any help would be great! Thanks

Matt

[MFW]

Any Hondaline Speedometer experts out there?

[El Camexican]

Any Speedo experts out there?

David Hasselhoff comes to mind.

[MFW]

Haha, good one!

[ps2fixer]

Far from an expert on these, but I've made reproductions from NOS sockets for these. The light housing shouldn't effect the light in any way, the wires goes directly to the socket/bulb. There should be a green wire + brown wire. Green is the ground, brown is the +12v and should only give power to the bulb when the light switch is turned on. Maybe the socket is corroded, or the bulb is failing?

Here's some photos to reference on my reproduction socket, it should look very similar to what you have.

https://www.ebay.com/itm/192928084416

[MFW]

Thanks Ps2fixer, I will take a look at the wires again. I took out the harness and cleaned all the connections. I even switched the bul because I thought it was bad. Do you still sell the harness?

Matt

[ps2fixer]

I do still make the harnesses (full OEM replacement style), just have a bit of a back order built up. Been trying to keep up with ebay stock, so haven't been able to dedicate much time to making harnesses. Harnesses just eat up a lot of time to make them.

[Jd110]

Are the rubber mounting grommets in place, under the head unit? Head unit shouldn’t be grounded(front-end is through neck bearings), but you can check with a multi-meter. You can also check continuity between the socket base and the end of green wire on the socket pigtail. If the light comes on when it touches the side of the head unit, tells me the head unit is grounded AND you lost the ground connection to socket.

[MFW]

The rubber grommets are in place. I will go through and clean and reconnect everything again. Thanks

Matt

[Jd110]

I just double checked mine.....I was wrong about the head unit not grounded. I’m getting ground through the speedo cable, now. Maybe, pull back the rubber boot from the socket. Just be careful not to rip it(grease wires so boot can slide a bit). You will see where the green wire is connected to back of socket and try cleaning it. Never tried to soldier that...but I would. Once you find the problem, you could then decide on buying new parts.

[ps2fixer]

The grounding of the speedometer housing shouldn't matter as the bulbs don't ground through the case, the socket is rubber mounted so the green wire (ground) runs directly to the bulb. It just sounds like a bad connection in the socket, or if the movement is more like a tap, could be a blown bulb and the filament is welding to the probe inside the bulb and lights up, and once turned off the extreme temp change breaks the weld and it drops back down and is free hanging (depends on bulb design/type internally). Ever had a headlight or tail light you could smack and it would come back on? That's what's happening in those cases.

FYI, you can remove the socket from the speedometer and the bulb will work still. You could check the socket connections out as well as the bulb and diag a bit more where you can see what's happening. Could try to wiggle the bulb to see if it's a socket connection problem, or lightly tap it to see if it's the bulb being blown just right where it cam light back up. If neither is bad, then I'd start digging down to where it connects to the harness and such.

Also the wiring probably is really old, so it's possible the insulation on the wire is brittle and broke inside the socket. Pushing the wire "in" on the socket and having it light up might be a sign of a bad wire, same story if you lightly pull on the wire and it doesn't work.

[Jd110]

260743Cory, here is a picture of where ground wire connects to the base of the socket. 260742
You can see I’ve got the ground wire disconnected in headlight bucket and touching the speedo it all works. So, if it works when touching the side of head unit...bad ground connection.

[ps2fixer]

I see, with it normally installed is it possible to get the socket housing to hit the speedometer housing? I thought the rubber mount made it near impossible for the two to come in contact unless you remove/damage the rubber grommet. The NOS sockets I found are the same design though, didn't know the rubber pealed back so easily.

[Jd110]

Yes, op describes it pretty well in first post. Possible it’s fixable. If not, good chance he can find a new one;). Win-win

[MFW]

I disconnected the wire harness to the speedometer and wired it directly to the main harness. Same out come. I even changed the bulb with a new one. Same outcome. I will keep digging and keep cleaning connections. Something has to give.... right? Haha

[ps2fixer]

Can you add a couple photos of the socket? Maybe we can spot something.

Also, you happen to have a multi meter and know the basics on how to use it?

[Jd110]

It plugs into the main harness, anyway. You had a hunch it is a ground issue and there are only a couple connections to check. It shouldn’t be difficult to check the base of the socket. You may have to cut the loom where it is heat crimped, to get the boot to slide down enough to access that. See the picture above-it’s not a great connection from the go. Again, check that green wire at the back of socket. Good luck!

[MFW]

So here are some pictures I took.
Picture #1 is of the wires going into the socket.
Picture #2 is of the light switch on but the light isn't working.
Picture #3 is of the light switch on and the socket touching the speedometer housing. 261025261026261027

[MFW]

Sorry, trying not to beat a dead horse here. I went through all the connections again and cleaned them again. They started off clean since its been in the high desert its whole life there is zero rust on anything.

[ps2fixer]

Interesting situation, sounds like a bad ground connection. Clearly the brown wire has good connection. I think the easiest test would be to disconnect the green wire only and ground the wire and see if the bulb comes on. If not then I'd suspect the wire is broken internally in the insulation. If it works, then I think we'd need to further test your grounding, or maybe something isn't hooked together right.

Do you have a multi meter and a basic understanding how to use it?

[MFW]

I took the harness that comes with the speedometer kit which is an extension to the main harness out and plugged it directly to the harness. Same issue. I might just get a small wire and have it tucked into the grommet and overlap it so it touches the house so it will ground and work correctly.

[ps2fixer]

Since it's just bullet terminals, try to plug it into the tail lgiht socket (green to green, brown to brown). If the tail light works and the bulb socket doesn't power the bulb, the green wire is bad. If it works, there's another electrical gremlin going on or hooked up incorrectly (photos of what it connects to wouldn't hurt).

[Jd110]

With-in the speedometer light harness, there are two green wires connected together, underneath the plastic loom.

[MFW]

I will take a look at it again. Thanks guys