Mystery lead

Jersey Big Mike

100K mile club
the LED's are replacements for 1157 bulbs that were 2 filament. Since the taillight is ALWAYS on, the second filament has to be brighter and since the TS and BRAKE both need to be brighter they share that filament. see https://mgaguru.com/mgtech/electric/et107a.htm for reference.

Your likely scenario is that the wire to the EHC that turns on the brakes got disconnected from the EHC.
Since it does not discriminate between front and back brakes, the "brake on" wire going to the EHC can be common to front and rear brake.

I would try and chase the wire from the rear brake banjo switch back towards the EHC.
 

Paul.uk

Member
the LED's are replacements for 1157 bulbs that were 2 filament. Since the taillight is ALWAYS on, the second filament has to be brighter and since the TS and BRAKE both need to be brighter they share that filament. see https://mgaguru.com/mgtech/electric/et107a.htm for reference.

Your likely scenario is that the wire to the EHC that turns on the brakes got disconnected from the EHC.
Since it does not discriminate between front and back brakes, the "brake on" wire going to the EHC can be common to front and rear brake.

I would try and chase the wire from the rear brake banjo switch back towards the EHC.
Thank you so much for that information I'm learning so much from all of you. I'm going to have another look soon. Fingers crossed.
 

Paul.uk

Member
Right I'm still confused. If i put a live feed to these wires from a seperate battery and an earth to the frame the brake lights work as normal, photo (brake light 1)figure 1. but this is without the ignition on as I will have bypassed it.
If I do the same to the wires marked 2 on the photo the brake lights are permanently on without the ignition on.
So I assume therefore that somewhere along the line there should be a feed to the first wire but I still cant work out where this is.

The second picture is I think the ignition wire or possibly the lighting circuit? If I attach that to the
positive terminal and switch the ignition on all the lights work except the brake lights. Even if I leave the seperate supply
connected to the wires in the first picture.

Could this mean I've a short in the lighting wiring/ignition circuit. I noticed that the battery has dropped almost
4v in about 10 days as well. There is an alarm but that seems very high to me considering its a brand new battery.

Unfortunatley all the wiring diagrams I've looked at so far dont match up with any I've seen and I dont have big dog wiring
as all the controls are Harley Davidson, but I dont know which harness was used. There are no ecu board that light up.
The orange wire seems to split into 2 red wires which I think go to the ignition switch.

I feel i'm getting closer and I know for sure the switchgear itself will work. But I'm still struggling to get my
head around where the live lighting circuit meets the brake light circuit.

I feel like an idiot asking all these questions, but I cant afford to take it to a shop at the moment, even if i could find one that
is not fully booked for the next 2 months, due to the covid back log of work.

Can any of you wonderful people educate me or give me any ideas on where to look next?
Thanks.
 

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Jersey Big Mike

100K mile club
At this point, looking closer at that module, I think that is a load equalizer meant to add a load for turn signals to flash.
If I see that correctly it only has 3 wires coming out of it correct?
If I am correct, there has to be another piece wired somewhere (relay/flasher module etc)

At this point, I would get a badlands module and replace that unit. Trace the wires from the turn signal switches back in the harness and trace the wires from each light and re-do it. They come with instructions and hopefully your harness uses unique color wires for everything it should.


For me there is a point of diminishing returns in time spent vs the appx 110usd for new module.
 

Paul.uk

Member
At this point, looking closer at that module, I think that is a load equalizer meant to add a load for turn signals to flash.
If I see that correctly it only has 3 wires coming out of it correct?
If I am correct, there has to be another piece wired somewhere (relay/flasher module etc)

At this point, I would get a badlands module and replace that unit. Trace the wires from the turn signal switches back in the harness and trace the wires from each light and re-do it. They come with instructions and hopefully your harness uses unique color wires for everything it should.


For me there is a point of diminishing returns in time spent vs the appx 110usd for new module.
Thanks. Would that affect the brake lights as the indicators all work but as you pointed out that the brake lights share the same led as the indicators would that module being faulty stop the brake lights from working?
 

Paul.uk

Member
Thanks. Would that affect the brake lights as the indicators all work but as you pointed out that the brake lights share the same led as the indicators would that module being faulty stop the brake lights from working?
Also does this mean the brake light led should be connected to the indicator led in the rear light, instead of the tail light? The tail light work as well?
 

Paul.uk

Member
Well knock me down with a feather duster. Turns out if I put these 2 combinations of wire together I get working brake lights as well as everything else working as well. So once I've made permanent connection etc that hopefully will be problem solved.
Thank you all again so much for your help and information. Ride free and ride safe.big dog problem solved_LI.jpg
 

Paul.uk

Member
Glad you found it.
Shrink wrap those connections and then wrap them with others in a sleeve to protect them.

And the correct module from badlands would have actually been https://namzcustomcycleproducts.com...ghting-modules/badlands-illuminatorn-pro-iii/
Thanks for all your suggestions and help. I've managed to wire one light today in between showers so still have to do the connection, the other rear light and then wrap and retie all the wiring back so it's secure and protected. I might still get a replacement module or even get the total loom checked at some point.
Ride free and ride safe..
 
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