71 delta 88 dash brake light ???
February 16th, 2012, 07:44 PM
#1
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Location: Alberta
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71 delta 88 dash brake light ???
Hi guys i just purchased a 71 delta 88 and while driving i noticed the dash brake light flickering on and off!!
What would cause this and is it a simple fix???
Scooter
What would cause this and is it a simple fix???
Scooter
February 16th, 2012, 07:54 PM
#2
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Join Date: Feb 2012
Posts: 18
There are two ways for the brake light to come on. One is the switch on the E brake assy. If the emergency brake pedal is hitting the switch, it will illuminate the light.
There is also a differential switch in the proportioning/ combination valve. If the pressure is different between the front and rear portions of the brake hydraulic system, the switch will turn the light on.
Regardless if the e brake checks out, its time to put the car on jack stands, remove all 4 wheels and perform a thorough brake check.
There is also a differential switch in the proportioning/ combination valve. If the pressure is different between the front and rear portions of the brake hydraulic system, the switch will turn the light on.
Regardless if the e brake checks out, its time to put the car on jack stands, remove all 4 wheels and perform a thorough brake check.
February 17th, 2012, 05:03 AM
#4
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Join Date: Jun 2009
Location: southeastern Michigan
Posts: 14,299
Did he not check the brake fluid level as part of his going through the car?
I find it hard to believe a competent mechanic would declare a brake system to be in "great condition" if the dash brake light is flashing.
February 17th, 2012, 05:40 AM
#5
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Join Date: Feb 2012
Posts: 18
Low brake fluid may not necessarily be an indication of a problem.
For example, if the car has discs, as the pads wear and the caliper pistons get further extended in thier bores, the fluid collects in the calipers. So low brake fluid may just indicate thinner brake pads and or rotors.
But something is defintely not right for the light to be on.
For example, if the car has discs, as the pads wear and the caliper pistons get further extended in thier bores, the fluid collects in the calipers. So low brake fluid may just indicate thinner brake pads and or rotors.
But something is defintely not right for the light to be on.
February 17th, 2012, 07:26 AM
#6
Old(s) Fart
Join Date: Mar 2007
Location: Northern VA
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Let's back up a little. The BRAKE light on the dash is fed +12V. The ground is switched. There are THREE possible ways for this ground to be closed and for the light to come on. First is the lamp test wire from the ignition switch. The switch provides a ground path with the key in the START position to test the lamp. The second path is the switch on the e-brake pedal. A plunger switch (just like the ones on the door jambs) grounds when the e-brake pedal is moved off the fully-released position. The third is the differential pressure switch in the brake circuit. A piston between the front and rear circuits can be moved if there is a pressure differential (if one circuit springs a leak), grounding a contact in the distribution block or combo valve.
An intermittent light can be caused by one of a several ways. The most common is that the e-brake pedal is not fully released. This often happens if the cables are not adjusted properly, as the excess slack prevents the pedal from moving to the fully released position. Try pulling up on the pedal the next time the light comes on. The second way is that one of the three wires that provides the ground path to the lamp has an intermittent short. The most likely one is the wire running to the differential pressure switch. The third (and least likely) is a problem with the differential pressure switch.
An intermittent light can be caused by one of a several ways. The most common is that the e-brake pedal is not fully released. This often happens if the cables are not adjusted properly, as the excess slack prevents the pedal from moving to the fully released position. Try pulling up on the pedal the next time the light comes on. The second way is that one of the three wires that provides the ground path to the lamp has an intermittent short. The most likely one is the wire running to the differential pressure switch. The third (and least likely) is a problem with the differential pressure switch.
February 17th, 2012, 07:53 AM
#7
Connoisseur d'Junque
Join Date: Sep 2010
Location: The Hudson Valley
Posts: 21,183
As Joe says, a loose(-ly adjusted) emergency brake cable can definitely cause this problem.
I've had it before on some A-body I drove (can't remember which). The cable wouldn't pull the pedal all the way up to its stop every time - it'd get to the first notch and stop there. In that position, the switch was almost making contact, and when the car would go over bumps, the light would go on and off.
The solution was to nudge the pedal up against the stop with my toe as I drove (much less effort than lying under the car and adjusting the cable
).
- Eric
I've had it before on some A-body I drove (can't remember which). The cable wouldn't pull the pedal all the way up to its stop every time - it'd get to the first notch and stop there. In that position, the switch was almost making contact, and when the car would go over bumps, the light would go on and off.
The solution was to nudge the pedal up against the stop with my toe as I drove (much less effort than lying under the car and adjusting the cable
).- Eric
February 17th, 2012, 10:58 AM
#9
Oldsdruid
Join Date: Dec 2007
Location: Southside Vajenya
Posts: 10,367
You may be able to tweak the pin switch on the park brake pedal a bit since my money says that's the culprit.
If you can get to it under the dash, spray a little WD40 down the e-brake cable. May take several tries to get enough in it to run down the full length of the cable. Sometimes there's enough gum or dirt in the cable sheath to cause parking brake problems.
Loose or stretched e-brake cables seem to be a common malady on 71-76 B&C body cars. The one on the 76 Ninety Eight is stretched to point of causing the warning lamp to flicker same as Scooter's. There is no adjustment left- there's already 8 washers on the equalizer trying to take up the slack.
Then you dig and dig and everywhere says NLA. And they were saying that ten years ago.
So, the e-brake pedal is cinched up with a ty-rap to keep the warning lamp off, and I do not use the e-brake.
If you can get to it under the dash, spray a little WD40 down the e-brake cable. May take several tries to get enough in it to run down the full length of the cable. Sometimes there's enough gum or dirt in the cable sheath to cause parking brake problems.
Loose or stretched e-brake cables seem to be a common malady on 71-76 B&C body cars. The one on the 76 Ninety Eight is stretched to point of causing the warning lamp to flicker same as Scooter's. There is no adjustment left- there's already 8 washers on the equalizer trying to take up the slack.
Then you dig and dig and everywhere says NLA. And they were saying that ten years ago.
So, the e-brake pedal is cinched up with a ty-rap to keep the warning lamp off, and I do not use the e-brake.
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