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Made by Monkeys

The Brake Sensor’s Gone Mad

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naperlou
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Blogger
it's always the whole instrument panel
naperlou   5/20/2013 9:06:44 AM
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Paul, This story is so often repeated that you think it would have been fixed by now.  The design of automobile instrument pannels is a sham.  That, in many cases, you have to take out a whole instrument pannel to check or change a bulb is silly.  It is somwhat depressing that this is still the case in the 21st century.

Pubudu
User Rank
Platinum
Re: it's always the whole instrument panel
Pubudu   5/20/2013 2:37:28 PM
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Paul, we have to be aware when we go for a agent they will quote us more usually not locking at the right problem.

Sometimes back I had a noise in my front left window when operating the glass, I also got a quote for repair that which is not in my budget from the agent, and they wanted to replace the pump. So I wanted to fix it as it is and get the vehicle back after paying the inspection fees only. Fortunately there is no noise at all after re-fixing it back and still it's working properly. 

DB_Wilson
User Rank
Gold
Re: it's always the whole instrument panel
DB_Wilson   5/21/2013 8:56:31 AM
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Many places don't look for the easy and simple fix first.  I repaired an intermittant brake warning light by adjusting the parking brake cable. 

kf2qd
User Rank
Platinum
That's an easy fix...
kf2qd   5/21/2013 11:55:14 AM
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Had a similar type problem with my wife's Plymouth Breeze. The Check engine light would come on because a sensor in the transmission was faulty. And this light was where it was really annoying at night. The Fix? A sript of Black Electricians Tape. Didn't see the light, could ignore the problem.

Ed Fuller
User Rank
Iron
Re: The Brake Sensor's Gone Mad
Ed Fuller   5/21/2013 12:03:18 PM
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Confession time.

In my younger years I once had a brake light that would come on whenever I applied my brakes.  My first thought was that there was a problem electrical connection, but then I learned that this was a feature of the brake system.  When the fluid was low in the master cylinder and the brakes were applied, the fluid shifted forward and the light sensor was exposed turning on the light.  Once the car was stopped or accelerating, the fluid shifted back covering the sensor and turning off the light.  Solution to the problem:  add fluid (I wasn't real big on preventive maintenace at the time).

I can't say if this is "normal" operation in all vehicles, but it was new to me at the time.  I had not given the light much thought before then and had supposed that it was to tell me when my brakes were "bad."

In hindsight, the problem was obvious but I guess we all have to learn sometime.

William K.
User Rank
Platinum
The fundamental problem with most dealer repairs.
William K.   5/21/2013 12:18:14 PM
The single HUGE problem with having a dealer service a vehicle is that they never repair anything, they only replace parts. Sometimes replacing a part is indeed the only way to solve the problem, but in many cases that is not what is actually required. So unless a problem clearly requires a part replacement that needs tools that I don't have access to, I do the repair myself. I am totally unwilling to pay $160 or more per hour to have somebody randomly change parts until a symptom goes away.

apod
User Rank
Iron
Re: The fundamental problem with most dealer repairs.
apod   5/22/2013 8:14:19 AM
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So agree with you. Had a similar experience with a Mini Cooper Dealer. Brought the vehicle in for a T'stat change, gasket was leaking, impossible to get to without mini hands, pun. They came back wtih about $10k of immediate needed repairs: new clutch to fix a mysterious leak (that was the antifreeze), new power steering fan, new tires, new radiator fan, and a couple other things. A year later, just the t'stat had to be replaced and also had to bring back because work was not good, I was still leaking out fluid. Go to a real mechanic.

ndjalva
User Rank
Iron
Re: The fundamental problem with most dealer repairs.
ndjalva   5/26/2013 9:01:05 AM
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Class ACT dealer mechanics are ASE idiots I can read the crap on the com puter but never learned mechanics. I spent 5 years to understand just a part a  of what I know about repairing Aircraft, boats, cars, trucks, plumbing, and the rest of the world. ASE is crap..........find an old timer to fix your car.

Ann R. Thryft
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Blogger
Re: The fundamental problem with most dealer repairs.
Ann R. Thryft   5/28/2013 4:05:41 PM
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I completely agree with William about the useless of dealers, maybe even more so. I've got an air bag sensor light on my 1996 Nissan Sentra that's been flashing for about 10 years. It doesn't mean there's anything wrong with the airbag--it means I'm supposed to waste an entire day, and a lot of dollars, going to the nearest dealer for them to turn it off. An entire day because that's how long it takes to get there and back (I live in the mountains), and wait for them to get to me, and then wait for them to do something. I'm only surprised that the sensor has lasted this long.



William K.
User Rank
Platinum
Re: The fundamental problem with most dealer repairs.
William K.   5/28/2013 9:04:11 PM
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Ann, sometimes disconnecting the battery wil reset those fault indications. But you also need to discharge the memory holding capacitors, Switching on the headlights while the battery is disconnected and the ignition switch is on should do that. It works for some brands and model years and is cheap and easy to try.

Ann R. Thryft
User Rank
Blogger
Re: The fundamental problem with most dealer repairs.
Ann R. Thryft   5/29/2013 11:38:10 AM
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Thanks, William. We already tried disconnecting the battery with no change. But not the other routine you mentioned--we'll try that next.



Tool_maker
User Rank
Platinum
Re: The fundamental problem with most dealer repairs.
Tool_maker   6/6/2013 4:23:28 PM
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@William K. I agree with your assesment of dealer mechanics as a rule, but I think this applies to other automechanics as well. I have used dozens of garages in the last ten years and have found that if the computer feed does not tell them what the problem is, they are totally lost. Sometimes they can figure it, but other times no. But that is not unique to automobiles. It extends to home appliances and office equipment as well.

  Incompetance extend to many disciplines these days. I have a brown spot on my leg that the surgeon swore he removed. "What is that?" "It's gone." Even though we could both clearly see the spot the doc kept telling me it was gone. A section of tile replaced with uneven grout joints and that area of the floor is uneven. Maybe the edge of the lawn gets trimmed and maybe not. I really love the service people who work by complaint. "Hey. You missed a spot, or you forgot the other side of the yard."

  I got into an arguement with a pest control service when I told them not to return. The office told me I had a contract and could not discontinue service. I told them they had voided the contract by doing shoddy work and I would no longer do business with people who only did a complete job in response to complaints. At least the mechanic at a dealer has some sort of factory training.

  End of rant.

Larry M
User Rank
Platinum
Aha! A Hall effect device! No wonder it failed.
Larry M   5/23/2013 3:38:08 PM
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I have concluded that Hall effect devices are simply too frail for the extended temperatures and vibration of an automotive environment. I've had a couple go intermittent and/or fail in my 1992 Mitsubishi (250 K miles). They never put them in some inexpensive assembly. You must buy a new distributor or throttle body assembly at a few hundred dollars each (assuming you use the dealer and not the junkyard).

I don't know how you would tell in advance of buying a car whether Hall effect devices were used but I would avoid them if I could figure out how to.

 

dnason@kicmail.com
User Rank
Iron
Fix the light - don't ignore it
dnason@kicmail.com   5/23/2013 4:23:21 PM
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I have to take exception to the last comment "I decided I can live with a red lamp in the lower left corner of the panel that comes and goes randomly."

There is a reason the light is red. The brake system is the single most important system in your vehicle. If you are learning to ignore the warning light then in the unlikely event the light comes on for a valid reason, it could be too late. If the vehicle is old enough to be found in a junkyard, you can probably find one for low cost. Less than 10 years old, I would suggest paying for the replacement or finding an aftermarket replacement.

William K.
User Rank
Platinum
Re: Fix the light - don't ignore it
William K.   5/23/2013 6:32:48 PM
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dnason, NO, the brakes are the SECOND most important system in a car. Steering is more critical because it allows you to avoid hitting things most of the time. A car can be driven fairly well without brakes, but when the steering stops working then there is big trouble a lot quicker than when there are no brakes. I have had both kinds of failures and so I know this first hand.

The steering failure was not a loss of power assist, it was a sudden loss of the upper bearing in the steering box, resulting in an instant increase to four turns of the wheel backlash. The brakes failures were a bursting of the front brake hose, which even though Chrysler claimed they had independant brakes, front and rear, when the front brakes were failed there were no brakes at all. Thatb happened twice, left side one year and the right side a year later. Evidently 1982 was a bad year for Chrysler brake hoses.

William K.
User Rank
Platinum
Re: Fix the light - don't ignore it
William K.   5/23/2013 6:40:22 PM
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That same red brake system failure light was also connected to the parking brake operator, and if the parking brake lever was not fully pused back into the released position then bumps would make the light flash. They were just too cheap to provide a secong light to warn about the parking brakes release lever. 

Another thing that would cause the light to come on occasionally would be a very small air bubble in a caliper, which would heat up and expand and cause a pressure differential across the pressure differential sensor, lighting the light. The bubble could be small enough to just barely change the feel of the brakes, but it would remind one that brake bleeding time was here. Chrysler never had a brake fluid low warning light because they did not want folks to be alarmed about the possibility of losing brake fluid. That comes straight from the chief body electrical engineer, quite a few years back.

tomintx
User Rank
Silver
Vehicle NOT designed by monkeys; Owned by one.
tomintx   5/23/2013 6:08:15 PM
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This discussion brings to mind a recent experience I had with 2001 Suburban.  

Symptom 1: Cruise Control failed.  Does not accept input, cannot set.

Guess: No idea, sounds expensive.  Ignore.

Symptom 2: Car failed safety inspection in April 2013 - no brake lights.

Guess: Combined failures; must be single failure point - brake switch at pedal.

Checked first because it was easy: Bulbs

Solution: Replace 2 bulbs and cruise control now works.  Car also passed inspection.

Note to self:  Check brake lights more often.  

ndjalva
User Rank
Iron
Re: Vehicle NOT designed by monkeys; Owned by one.
ndjalva   5/26/2013 8:51:47 AM
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Great!

Only pilots and operators can screw up a simple thing , oops  i forgot the " I can fix that 'duct tape' (red green)crew. Not designed by monkeys , operated by monkeys.

LloydP
User Rank
Gold
Re: Vehicle NOT designed by monkeys; Owned by one.
LloydP   5/28/2013 5:57:52 PM
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Most cruise control systems disable when the brakes are applied. The brake switch input is pulled to ground through the brake lights, which act as a low resistance path to ground when the filaments are cold. Applying the brakes puts a 12 volt signal on this input. If the brake lights are open circuit (a/k/a burned out) the brake input may be pulled up to 12 volts internally in the cruise module. This is a safety feature that defaults the cruise to Off.

loadster
User Rank
Gold
Re: Vehicle NOT designed by monkeys; Owned by one.
loadster   5/29/2013 3:07:08 PM
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Monkeys don't own suburbans. But your brain is being sublet to one. If your brake lights opening breaks your cruise control, then your cruise control is somehow using the brake continuity as chassis ground, either DC or capacitive. I'd buy a chiltons or a haynes book with schematics and try and figure it out before it bites you somewhere in the wrong place at a dangerous time. Or you can keep that monkey riding in your brain housing group, and hope for a barrel of monkeys to pull you out. I own a 96 yukon so thanks for the insight if my cruise ever snaps.

William K.
User Rank
Platinum
Re: Vehicle NOT designed by monkeys; Owned by one.
William K.   5/29/2013 3:54:34 PM
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The cruise control has to be linked to the brakes somehow so that it would allow one to stop the car. It used to be that there was a separate normally closed switch along with the nornally open stoplight switch on cruise control cars. But then with adding a controller chip they decided that the brake light signal could be used, but it would need to verify that the brake light power feed was live in order to have the system be safe. So the problem could be in that area.

loadster
User Rank
Gold
Re: Vehicle NOT designed by monkeys; Owned by one.
loadster   5/30/2013 9:34:15 AM
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Agreed; cruise must be overridden by brakes and if brakes aren't right, then cruise should be disabled. My question is whether the brake light burn-out means current is excessive because a ground is corroded on the cruise circuit. Whenever fuses or lights burn out, my discovery is not quashed until the reason is defendable. Unless the car has recently been driven thru a lake. On the separate issue of resetting "check engine" flags, one can buy a DBII diagnostic for $50 to $150 or try the battery disconnect and headlight discharge method. You run the risk of resetting all your "learned" PROM if your car does that. I discovered on a late model Volvo that you can reset the service counter and "service soon" light by simply holding down the trip odometer button when turn on the ignition. Kind of like holding down a special key sequence on hand-held electronics or computers when you cycle power. I like things simple. The new PHEV don't apply.

tekochip
User Rank
Platinum
Re: Vehicle NOT designed by monkeys; Owned by one.
tekochip   5/30/2013 12:04:22 PM
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Aside from the brake switch, some cruise control systems include a dump valve that's attached to the brake pedal. When you step on the brake the valve opens the vacuum in the cruise control servo which release the accelerator and serves as a mechanical system to shut down the cruise control.


William K.
User Rank
Platinum
Re: Vehicle NOT designed by monkeys; Owned by one.
William K.   5/30/2013 4:44:58 PM
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Loadster, you need to seriously review basic circuit theory, concerning tha light burnout problem. Only in certain areas of the charging system can corrosion and the resultant high resistance cause an excess voltage, which would lead to excessive lamp current. 

But a failure of a lamp to light because of corrosion would look like a burned out bulb, but it would instead be a poor connection preventing illumination. And so those unable to test a lightbulb to see if it has failed, no hope of effecting a repair by means of replacing a good bulb. The fact is that in order to produce an effective repair one must know what the problem is. Otherwise one is simply shooting randomly in hopes of hitting the right target. And you should be aware that sometimes those very inferior lamp bulbs made in China only last a few hours. 

loadster
User Rank
Gold
Re: Vehicle NOT designed by monkeys; Owned by one.
loadster   5/31/2013 9:10:12 AM
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william k. I'll take your advice on circuit theory for what its worth. I was speaking to the possibility that the cruise control had lost its normally available return path to chassis ground and was parasitically referenced to the brake light return. Not that there was corrosion on the bulb connection though that is a more common scenario. This is all just spherical tuba lube, trying to troubleshoot and recommend from virtual, intangible perpsective.

William K.
User Rank
Platinum
Re: Vehicle NOT designed by monkeys; Owned by one.
William K.   5/31/2013 7:36:59 PM
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Loadster, I have done a fair amount of successful troubleshooting from just this kind of distance on a number of occasions. It has saved me from a service call to someplace in the far northern realms of Canada in a February. That was a cold trip I was happy to avoid. Besides, remote diagnostics is an interesting game, it can be played as a real game if one team has the results of a good FMEA, and the other side is familiar with a design. Probably not a Parker Brothers best seller, but how many party type board games are made for engineers?

But your previous post appeared to me to be linking a lamp failure to an overvoltage caused by a poor ground, which is why the comment about circuit theory. I may not have perceived your meaning correctly, if so, apologies. 

jbourass
User Rank
Iron
2006 F-150 Brake Sensor/Sensor Ring Malfunction
jbourass   5/23/2013 6:38:53 PM
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I had the same problem with my 2006 F-150 and after troubleshooting the system (it took some time and an unnecessary sensor replacement) we found out the following:

A) Almost always the antilock sensor (except if mishandled or        destroyed) is seldom ever the culprit. This is a bullet proof part.

B) This malfunction usually appears when you change or replace the brake disk.

C) The disk has two removable parts: The Bearing and the Sensor Ring (usually a toothed pinion-like ring).

We found out that the when I purchased new disks, the sensor ring (which is not locked in place) was knocked out of position during shipping. Two things would happen: The check engine or brake light would come on and/or the antilock firing system was triggering when the brake was applied.

When you check the alignment of the Hall effect sensor ring with the wheel mounted, if the sensor ring is misaligned, a noticeable wobbling of the ring against the brake sensor will be observed when turning the wheel by hand (use a flashlight). The sensor ring and the sensor must never come into contact, but a small constant gap should be observed between the two parts.

This is the reason why Ford is not selling replacement parts for the disk assembly anymore and, if anything happens to the disk, bearing or ring, you have to purchase the complete disk assembly. Then again, even with a new disk assembly no one can warranty that the sensor ring is in alignment until you mount the new assembly and re-check the aligment of the sensor ring against the sensor after each repair or replacement.

The re-aligment procedure is fairly easy, check the opposite wheel (or consult the shop manual) ring-to-sensor gap and set the affected wheel ring to this tolerance. Don't forget to apply some thread lock or CA glue  between the sensor ring and the disk brake housing to avoid future dislplacement

Good luck and may God have mercy on you all new F-150 owners.

John
User Rank
Gold
Helms shop manual
John   6/5/2013 5:08:47 PM
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Helms prints the shop manuals, if they are available.  I would check them out for a shop manual if you plan on keeping the truck.  At least then you will have something to help learn how to trouble shoot the truck.  $150 parts store OBD code reading devices are very vague. 

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