| Author |
Message |
Rifai.Ad
Samba Member
Joined: December 24, 2019
Posts: 49
Location: Trollhattan, Sweden
|
 Posted: Today 6:12 am Post subject: 1971 Super Beetle brake light fault |
 |
|
After coming back to my bug after a few months of non-use due to studies, I find that everything works like before except the brake lights. The blinkers and the "running lights" work perfectly. I have checked the fuse and it's got between 10 and 12 volts on both ends. I have also checked the actual brake light line with a voltmeter, and when depressed it seems to give only around 3 to 4 volts (both the right and the left brake lights). I have also checked the two identical switches I found on my master cylinder, and with the ignition on, one of the pins gives 12 volts while the other outputs none. This is the same on both switches.
I do remember having brake light trouble back when I had battery problems, but I didn't get to drive it around and charge the battery to see if that solves anything. Could it be the brake cylinder switches (if those even have anything to do with the brake lights)? I should mention they worked perfectly before going into hibernation. |
|
| Back to top |
|
 |
Cusser
Samba Member
Joined: October 02, 2006
Posts: 31374
Location: Hot Arizona
|
| Posted: Today 6:31 am Post subject: Re: 1971 Super Beetle brake light fault |
|
|
Disclaimer: You're in Europe, I don't know what European models have.
This is a USA diagram. You may or may not have third terminal 81a.
The two switches on the master cylinder are essentially a redundancy. These are simple pressure/contact switches, and there should be continuity between the two parallel terminals when the brake pedal has been pressed down, ASSUMING THAT THE BRAKE HYDRAULICS PROVIDE ENOUGH PRESSURE TO ACTUATE THEM.
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
|
| Back to top |
|
|
Rifai.Ad
Samba Member
Joined: December 24, 2019
Posts: 49
Location: Trollhattan, Sweden
|
| Posted: Today 6:38 am Post subject: Re: 1971 Super Beetle brake light fault |
|
|
| Cusser wrote: |
Disclaimer: You're in Europe, I don't know what European models have.
This is a USA diagram. You may or may not have third terminal 81a.
The two switches on the master cylinder are essentially a redundancy. These are simple pressure/contact switches, and there should be continuity between the two parallel terminals when the brake pedal has been pressed down, ASSUMING THAT THE BRAKE HYDRAULICS PROVIDE ENOUGH PRESSURE TO ACTUATE THEM. |
It didn't cross my mind to check for continuity between those two, I'll do so tomorrow! The brake pedal seemed stiff, but I'll make sure the brakes actually work too. Thanks a lot! |
|
| Back to top |
|
|
cjsuner
Samba Member
Joined: January 04, 2013
Posts: 476
Location: Bay area CA
|
| Posted: Today 8:36 am Post subject: Re: 1971 Super Beetle brake light fault |
|
|
One way to check if it is a wiring or switch problem is to unplug the connector from the switch on the master cylinder, and take a paperclip and use it as a jumper between 82a and 81 (with key on). If you get brake lights, it probably means that your switches are bad (common thing to fail). If you don't your problem is gonna be in the wiring somewhere.
You could test if it is your 82a (power) or 81 by running a jumper from some source of 12v power, and then touching the 81 terminal, esstinally doing the same trick with the paper clip as above, just using a different source of power. This will tell you if it is a power issue, or a signal wire (81) issue.
_________________
71' Super Convertible (Orange)
74 Super Beetle (Red) |
|
| Back to top |
|
|
|
