Hi all, I used the search function and read the posts.
The problem may be that the brake light switch on my 63 single MC Bug may have failed internally and is keeping the brake lights on. The brake lights were working and there haven't been any changes. The brakes work and release in the regular manner.
I checked the grounds, bulbs, fuses, etc. Before I get under there and do more checking (it was about 105 degrees in my AZ driveway today). Has anybody ever seen an MC brake light switch cause this? Is replacing the switch my next test?
Thanks for any replys.
Brake switch possible failure 63 Bug
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Ol'fogasaurus
- Posts: 17881
- Joined: Mon Nov 13, 2006 10:17 pm
Re: Brake switch possible failure 63 Bug
Some thoughts; in no particular order have you checked:
Pull the wire off the switch and see if the brake lights go off.
Double check the end play between the pedal rod and the MC.
Check the conditions of the soft lines (there are four as I remember); they can get old, swell or get blocked.
Flushed the brake system replacing contaminated fluid; moisture in the fluid can swell/expand. Check all connections also for areas where moisture can get in.
And yes, the switches can fail to work, stick, leak or the end can blow out.
Pull the wire off the switch and see if the brake lights go off.
Double check the end play between the pedal rod and the MC.
Check the conditions of the soft lines (there are four as I remember); they can get old, swell or get blocked.
Flushed the brake system replacing contaminated fluid; moisture in the fluid can swell/expand. Check all connections also for areas where moisture can get in.
And yes, the switches can fail to work, stick, leak or the end can blow out.
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Marc
- Moderator
- Posts: 23741
- Joined: Thu May 23, 2002 12:01 am
Re: Brake switch possible failure 63 Bug
Check for a pebble stuck between the pedal stop on the floorboard and the "tail" of the brake pedal. That, and a misadjusted pushrod are the two most common causes of this symptom - if there's no freeplay, the compensating port that relieves pressure to the reservoir remains closed...and after driving for a while the fluid heats up and expands. Eventually you'll notice the brakes dragging, but at first the only evidence is the brakelamps staying on.
If the compensating port is open as it should be when the pedal's "up", there cannot be residual pressure to the switch even if there is a hose or fluid-contamination problem.
ANY perceptible freeplay is enough to avoid the problem, but the spec is 1mm at the pushrod (which translates to about ⅛" at the pedal). Ordinarily the pushrod length is not to be adjusted after the car leaves the factory (adjusting the pedal stop is instead recommended) but if the pedal is at least 8" back from the firewall and there's no freeplay, adjusting the pushrod would be in order.
If the compensating port is open as it should be when the pedal's "up", there cannot be residual pressure to the switch even if there is a hose or fluid-contamination problem.
ANY perceptible freeplay is enough to avoid the problem, but the spec is 1mm at the pushrod (which translates to about ⅛" at the pedal). Ordinarily the pushrod length is not to be adjusted after the car leaves the factory (adjusting the pedal stop is instead recommended) but if the pedal is at least 8" back from the firewall and there's no freeplay, adjusting the pushrod would be in order.