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vanis13
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Joined: August 15, 2010
Posts: 3093
Location: ABQ NM USA.... Except when not
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 Posted: Fri Sep 01, 2017 10:16 am Post subject: What is relationship between dash brake light and pedal press? |
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What is relationship between dash brake light and brake pedal press?
When I press on the brake pedal the dash brake indicator light comes on...sometimes.
Fluid is at max mark. Tail brake lights are functional.
Does not come on while driving. Seems to happen more frequently when at stop/idle. when id does happen, if i r-press the pedal, it goes off for a second or two then comes back on when pedal is pressed. Also seems to do this off-on behavior when I have pedal pressed and light comes on, then I press pedal more and light goes off for a second ten comes back on.
Ideas?
_________________
83.5 Westy with Subaru 2.5, 4 spd manual, center seat, COLD A/C on 134a!, Winter camp heated with an Espar B4 gasoline furnace
www.SuperVanagon.com - some stuff I make |
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Ahwahnee
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Joined: June 05, 2010
Posts: 9799
Location: Mt Lemmon, AZ
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| Posted: Fri Sep 01, 2017 10:47 am Post subject: Re: What is relationship between dash brake light and pedal press? |
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There are two brake light pressure switches. The brake will operate so long as one of those switches is functional.
Strange things happen (or are supposed to happen) when just one of the switches has failed - you might want to check (ohmmeter) the operation of each switch.
The other possibility is the handbrake switch which I suppose could be such that it has a hair trigger and comes on with certain motion. For this you might see if just fiddling with (not yanking) the handbrake handle causes the light to flicker. |
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crazyvwvanman
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Joined: January 28, 2008
Posts: 9923
Location: Orbiting San Diego
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| Posted: Fri Sep 01, 2017 11:11 am Post subject: Re: What is relationship between dash brake light and pedal press? |
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In 80-84 models the dash brake warning light module is connected to the 2 brake pressure switches. If there is a large enough pressure mismatch between the front and rear hydraulic sections the dash brake warning light is supposed to come on so the driver knows and can get it fixed.
One possible explanation for your described symptoms would be that one circuit isn't always holding pressure. If so there should be a loss of fluid or the master cylinder is leaking internally past one of the seals.
The 85+ vans don't have this. They have a fluid level warning float switch on the fluid reservoir instead.
The brake switches are different for 80-84, with 3 wiring pins on the switch instead of only 2 pins in 85+ vans.
Mark |
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vanis13
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Joined: August 15, 2010
Posts: 3093
Location: ABQ NM USA.... Except when not
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| Posted: Fri Sep 01, 2017 12:14 pm Post subject: Re: What is relationship between dash brake light and pedal press? |
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Ahwahee - it definitely isn't the parking brake, I have ruled that out.
| crazyvwvanman wrote: |
In 80-84 models the dash brake warning light module is connected to the 2 brake pressure switches. If there is a large enough pressure mismatch between the front and rear hydraulic sections the dash brake warning light is supposed to come on so the driver knows and can get it fixed.
One possible explanation for your described symptoms would be that one circuit isn't always holding pressure. If so there should be a loss of fluid or the master cylinder is leaking internally past one of the seals.
The 85+ vans don't have this. They have a fluid level warning float switch on the fluid reservoir instead.
The brake switches are different for 80-84, with 3 wiring pins on the switch instead of only 2 pins in 85+ vans.
Mark |
83.5 van for me...how to determine the internal Master cylinder leak? I don't seem to be losing any fluid.
_________________
83.5 Westy with Subaru 2.5, 4 spd manual, center seat, COLD A/C on 134a!, Winter camp heated with an Espar B4 gasoline furnace
www.SuperVanagon.com - some stuff I make |
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danfromsyr
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Joined: March 01, 2004
Posts: 15144
Location: Syracuse, NY
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| Posted: Fri Sep 01, 2017 12:56 pm Post subject: Re: What is relationship between dash brake light and pedal press? |
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one of the light switches can and is most likely slow to make contact.
ie. requires more pressure than the other to make contact.. this will trigger the warning light.
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| Abscate wrote: |
| These are the reasons we have words like “wanker” |
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vanis13
Samba Member
Joined: August 15, 2010
Posts: 3093
Location: ABQ NM USA.... Except when not
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| Posted: Fri Sep 01, 2017 1:06 pm Post subject: Re: What is relationship between dash brake light and pedal press? |
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| danfromsyr wrote: |
one of the light switches can and is most likely slow to make contact.
ie. requires more pressure than the other to make contact.. this will trigger the warning light. |
that is interesting. what seems to be happening on my side is almost opposite of that. when I first press the pedal lightly it is ok then when I press it harder then the light comes on.
_________________
83.5 Westy with Subaru 2.5, 4 spd manual, center seat, COLD A/C on 134a!, Winter camp heated with an Espar B4 gasoline furnace
www.SuperVanagon.com - some stuff I make |
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fxr
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Joined: December 07, 2014
Posts: 2321
Location: Bay area CA
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| Posted: Fri Sep 01, 2017 3:35 pm Post subject: Re: What is relationship between dash brake light and pedal press? |
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| vanis13 wrote: |
| danfromsyr wrote: |
one of the light switches can and is most likely slow to make contact.
ie. requires more pressure than the other to make contact.. this will trigger the warning light. |
that is interesting. what seems to be happening on my side is almost opposite of that. when I first press the pedal lightly it is ok then when I press it harder then the light comes on. |
Double-check that your brake light comes on when you press gently - my guess is that it doesn't, and only comes on when you press quite hard. This will be especially noticeable with the engine switched off. I bet only one switch is working properly, and in the 83/84 vans this will make the brake warning light come on. This is meant to be a warning for different pressures in the two circuits - but in Real Life is just a useful indicator that a brake light switch has failed. 
They're cheap enough, I carry a spare.
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Jim Crowther
1984 1.9l EJ22 Westy Wolfsburg Edition
Vespa GTS 300 |
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theadventureneverends
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Joined: December 24, 2009
Posts: 585
Location: Gig Harbor WA
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| Posted: Fri Sep 15, 2017 11:45 am Post subject: Re: What is relationship between dash brake light and pedal press? |
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I have a 91 with the ignition off and key in or out when I press on brake pedal my lower right red oil light glows.
If running and press on brake pedal it does not glow.
My brakes are in good working order.
Normal? |
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