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2008Harley Davidson FLHTCU
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Discussion Starter · #1 ·
My 08 FLHTCU (66,933 miles) has an ongoing issue with brake lights. Started as cruise would not engage and 6 gear indicator light wouldn’t work. Checked and found brake light constantly on. Had the plastic tab replaced on the brakes switch. Worked for a time then did it again with the addition of intermittent charge warning light, no signals and no radio/clock. Replaced voltage regular, brake switch but no go. After sitting for a while all will work for only about a mile. Today all worked fine for a mile then cruise control would not set and brake lights stay on. Got home and 20 minutes later brake lights were operation when front or rear is pushed.
Codes vary but latest ones are:
P0572 Brake Switch Low
P0563 Battery Voltage High
P0134 Front Oxygen Sensor Inactive
P0154 Rear Oxygen Sensor Inactive
B0563 Battery Voltage High
B1006 and B1007 (Accessory Line Overvoltage Instrument?)

Any one have a similar issue or any thoughts?
 

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My 08 FLHTCU (66,933 miles) has an ongoing issue with brake lights. Started as cruise would not engage and 6 gear indicator light wouldn’t work. Checked and found brake light constantly on. Had the plastic tab replaced on the brakes switch. Worked for a time then did it again with the addition of intermittent charge warning light, no signals and no radio/clock. Replaced voltage regular, brake switch but no go. After sitting for a while all will work for only about a mile. Today all worked fine for a mile then cruise control would not set and brake lights stay on. Got home and 20 minutes later brake lights were operation when front or rear is pushed.
Codes vary but latest ones are:
P0572 Brake Switch Low
P0563 Battery Voltage High
P0134 Front Oxygen Sensor Inactive
P0154 Rear Oxygen Sensor Inactive
B0563 Battery Voltage High
B1006 and B1007 (Accessory Line Overvoltage Instrument?)

Any one have a similar issue or any thoughts?
Brake lights work on a cold bike, up until a mile or so into the ride...

How long has it been since a brake flush? Should be every 48 months minimum!

That brake light problem combined with the cruise failing to set... The curse will not set if the brake light is activated.
The rear brake switch is activated by brake line pressure.
The line pressure can increase due to heat if the brake fluid has water contamination.
Water gets hot, expands, eventually turns to steam and locks up the rear wheel or cooks the brake pads. All the while activating the brake light.

Heat and pressure can be greatly enhanced by a bent or warped brake rotor... Check em for flatness.

I would start with a very through brake cleaning and brake flush.
Sorry i'm not much help with the electronic side of the house. I get hydraulics though.

Sorry it took so long for me to see this post. I just caught it today.
Please let me know your outcome, or further explanation. Thanks!
 
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2008Harley Davidson FLHTCU
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Discussion Starter · #3 ·
Brake lights work on a cold bike, up until a mile or so into the ride...

How long has it been since a brake flush? Should be every 48 months minimum!

That brake light problem combined with the cruise failing to set... The curse will not set if the brake light is activated.
The rear brake switch is activated by brake line pressure.
The line pressure can increase due to heat if the brake fluid has water contamination.
Water gets hot, expands, eventually turns to steam and locks up the rear wheel or cooks the brake pads. All the while activating the brake light.

Heat and pressure can be greatly enhanced by a bent or warped brake rotor... Check em for flatness.

I would start with a very through brake cleaning and brake flush.
Sorry i'm not much help with the electronic side of the house. I get hydraulics though.

Sorry it took so long for me to see this post. I just caught it today.
Please let me know your outcome, or further explanation. Thanks!
Thanks, makes sense to me. Replaced brake switch with a HD one (previous was aftermarket) which seems to have solved it for now. Will do a brake flush if it returns or next time I do a service
 

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Thanks, makes sense to me. Replaced brake switch with a HD one (previous was aftermarket) which seems to have solved it for now. Will do a brake flush if it returns or next time I do a service
That brake flush is easily overlooked. It causes s chit ton of problems if not flushed.
Everything from brakes locking up at freeway speed to total brake pedal lock out.
(You could park a truck on the brake pedal and it will NOT move!)

Error on the side of safety! Murphey doesn't need any help... Just sayin' (y)

Ride safe and have fun!
 
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