brake light problem (03 FXDX)
Road Master
Joined: Feb 2012
Posts: 1,217
Likes: 6
From: bfe
if you pump brakes light gets brighter ? run a test lead across pressure switch wires with them unplugged if light is bright its either pressure switch or air in line but I doubt air in line as the pressure switch is a 60psi switch . my friends bike had kinda same problem last month one of spade connectors on switch was burned thru and barley making contact . we took pressure switch to autozone and got one like it for under 10 bucks ( Harley dealers 65 miles from us )
Seasoned HDF Member
Joined: May 2008
Posts: 21,176
Likes: 12,748
From: South Carolina
to be perfectly honest, the rear brake light doesn't work that great, it seems I need to pump the brake several times to get it to come on, but as it comes on, with each brake pedal push the light increases in intensity until it lights as it should (think of a dimmer effect)
But for the purpose of testing the switch, it doesn`t matter, you just want to connect the ohmmeter to those wires and actuate the brake lever and find out if the switch is working properly.
If it is not, you will need to disassemble the control housing and inspect the switch.
Tourer
Joined: Aug 2009
Posts: 477
Likes: 8
From: Kennedale,Tx
I vote for dirty terminals on rear. OP said he pulled wires off, put back on and light works now but gets brighter and brighter, clean terminals and wire ends and a bit of dilectric grease.
As far as front, lever hits tip of pin to shut off light. Get at tip of switch and with thin bladed screw driver work the plunger. If it moves free do a continuity check and work the tip, Ohm readings should be consistant; open and closed, if closed, ohm value should be low, like .01 and should be consistant. Cycle switch like 50 times, Ohm value should be the same.
As far as front, lever hits tip of pin to shut off light. Get at tip of switch and with thin bladed screw driver work the plunger. If it moves free do a continuity check and work the tip, Ohm readings should be consistant; open and closed, if closed, ohm value should be low, like .01 and should be consistant. Cycle switch like 50 times, Ohm value should be the same.
Outstanding HDF Member
Joined: Dec 2012
Posts: 2,557
Likes: 235
From: Texas
How long has it been since you serviced the rear brake system and replaced the rear pads? The rear brake switch is a normally open, direct pressure switch so it is very possible that the switch is gunked up from old brake fluid...look in your master cylinder and see if there is gunk in the reservoir. Brake fluid collects moisture and makes sludge that will settle in the reservoir and can be pushed into the system.
Why spend hours and HOURS trying to fix a $17 part that they can get at the local auto parts store...only to have it fail again because the source of the problem still remains...go get another switch, clean and flush the system with new brake fluid, bleed it and get back on the road. Total cost is less than $30 and takes about an hour...
Maybe it is because I would rather ride than work on my bike. I also have an older Super Glide so when it was time to replace the rear pads, I found a lot of sludge in the master cylinder. I totally overhauled the system with a rebuild on the master and caliper, put in a new switch, and completely flushed out the line. Took me about three hours and cost just over $100 with OEM parts...the HD OEM master cylinder rebuild kit for my bike was expensive at $75...but it was done once, done right.
Why spend hours and HOURS trying to fix a $17 part that they can get at the local auto parts store...only to have it fail again because the source of the problem still remains...go get another switch, clean and flush the system with new brake fluid, bleed it and get back on the road. Total cost is less than $30 and takes about an hour...
Maybe it is because I would rather ride than work on my bike. I also have an older Super Glide so when it was time to replace the rear pads, I found a lot of sludge in the master cylinder. I totally overhauled the system with a rebuild on the master and caliper, put in a new switch, and completely flushed out the line. Took me about three hours and cost just over $100 with OEM parts...the HD OEM master cylinder rebuild kit for my bike was expensive at $75...but it was done once, done right.
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Tourer
Joined: Aug 2013
Posts: 260
Likes: 0
From: Phoenix, AZ
again great info guys, so here's the latest update, I was letting it go for now despite the obvious risk then all the bikes on the 101 for AZ bike week motivated me to get at it again, here's what I found
REAR-
I disconnected the terminals then bridged them with a standard ATC fuse, brake light lit right up, as far as I am concerned that is conclusive evidence the rear switch is dead- to which it doesn't seem to work at all anymore despite the number of pumps
FRONT-
I jumped the O/W wire to the R/Y wire at the fork stem which also activated the light, I tested for 12V on the R/Y wire when engaging the brake lever and no voltage, this also tells me the front switch is either dead or malfunctioning
So I will replace the rear switch and flush the system and begin to troubleshoot the front switch
Does Auto Zone carry the pressure switch? Something like THIS?
REAR-
I disconnected the terminals then bridged them with a standard ATC fuse, brake light lit right up, as far as I am concerned that is conclusive evidence the rear switch is dead- to which it doesn't seem to work at all anymore despite the number of pumps
FRONT-
I jumped the O/W wire to the R/Y wire at the fork stem which also activated the light, I tested for 12V on the R/Y wire when engaging the brake lever and no voltage, this also tells me the front switch is either dead or malfunctioning
So I will replace the rear switch and flush the system and begin to troubleshoot the front switch
Does Auto Zone carry the pressure switch? Something like THIS?
Last edited by supermanotorious; Apr 4, 2014 at 09:33 PM.
Thread Starter
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Tourer
Joined: Aug 2013
Posts: 260
Likes: 0
From: Phoenix, AZ
got the rear switch from HD, wah lah! rear brake light works great, we bled the system and there was definently air in it, maybe the old switch is good but had air in it, I'll hold on to it just in case
here is a pic of the front, the switch is working properly but maybe a former tech did not put the 'V' clip back in, what are your thoughts?
here is a pic of the front, the switch is working properly but maybe a former tech did not put the 'V' clip back in, what are your thoughts?
Thread Starter
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Tourer
Joined: Aug 2013
Posts: 260
Likes: 0
From: Phoenix, AZ
OK so I put a speed clip in there for the 'V' clip and I could tell the switch was badly misaligned before I got in there, in fact the plunger boot was smashed against the edge of the hole it extrudes through to contact the lever, I filed back the metal clip that "locks" the switch down as it appeared to possibly cause a short, once all assembled, I do have a short and keep popping the fuse, any idea how the short is occuring? It only happens once assembled, with the housing apart the circuit works as it should, the wires appear to be in good shape
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Tourer
Joined: Aug 2013
Posts: 260
Likes: 0
From: Phoenix, AZ
I think the short was caused by the clip I ground down, so I ground it further to the yellow line, the purple arrow shows where I think the short was occurring, when the switch housing was compressed the clip and wires they were pressed together
Now I am happy to report lights are working properly!
video was super helpful.
Now I am happy to report lights are working properly!
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