Mechanic in the house?
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My mother's Cadillac (early 90's) has a tail or brake light that likes to come on while the car is parked and drains the battery completely overnight. It can go days without happen, then presto, the batter is dead. Found out once when someone called and said the tail light was on and found that just the right side tail light (or brake like don't remember which) would come on for no known reason. Anyone heard of such a thing? The lights all work like normal, but this one light likes to come on at will when the car is off and parked. She cannot really be connecting and disconnecting the battery every time she uses the car, but do not want to take it in and see a huge bill without any results. Any ideas?
Rocky <>< Recent Blog Post: Silverlight Domain Names up for grabs! Thinking about Silverlight? www.SilverlightCity.com
Hmmmm... It's been a while, but, 1. It's nearly 20 years old, and they didn't have all the electronic, computer-controlled whizbangs in them that make real diagnosis impossible. 2. It's intermittent. 3. It drains the battery overnight, which a single bulb should not do. Ergo: It's in the wiring harness, and probably involves more than one wire. I'd guess that abrasion has worn off the insulation on a couple of wires where the tail light harness makes a sharp bend around a metallic chassis component, but that's only a starting point. Some automotive wiring uses the quaint notion of wiring the hot side (positive) to each device and switching the negative to ground to turn them on. This causes some interesting sneak paths for current when something goes wrong. 1. Start at the brakelight; open it up and make note of the color of each of the wires. Expose the wiring from back to front as you work your way forward to the fuse block and visually inspect the wires for damage, especially where they go around corners or pass through a hinge, such as the trunk lid. Be prepared to spend all day at it, though, as getting to the harness isn't easy. or 2. Connect a time domain reflectometer at the bulb socket and ping each wire separately. Calculate the distance from the socket to the first discontinuity for each wire. Measure the shortest distance of the two and expose the cable at that distance from the socket and repair the damage. Simple... :) It would be great if you could arrange to do the search while the light is on, but Murphy's Law assures that you won't get that lucky. Good luck! :-D
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
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I know nothing about cars. Sorry I can't help on this one. :(( But some of the suggestions are hilarious. [Joke] How many software engineers does it take to fix car's light? None, we know nothing about cars [/Joke]
Yusuf Oh didn't you notice, analogous to square roots, they recently introduced rectangular, circular, and diamond roots to determine the size of the corresponding shapes when given the area. Luc Pattyn[^]
That's actually funny! :laugh:
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Rocky Moore wrote:
Any ideas?
Parking lights. Look in the owners manual how they get activated.
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Hmmmm... It's been a while, but, 1. It's nearly 20 years old, and they didn't have all the electronic, computer-controlled whizbangs in them that make real diagnosis impossible. 2. It's intermittent. 3. It drains the battery overnight, which a single bulb should not do. Ergo: It's in the wiring harness, and probably involves more than one wire. I'd guess that abrasion has worn off the insulation on a couple of wires where the tail light harness makes a sharp bend around a metallic chassis component, but that's only a starting point. Some automotive wiring uses the quaint notion of wiring the hot side (positive) to each device and switching the negative to ground to turn them on. This causes some interesting sneak paths for current when something goes wrong. 1. Start at the brakelight; open it up and make note of the color of each of the wires. Expose the wiring from back to front as you work your way forward to the fuse block and visually inspect the wires for damage, especially where they go around corners or pass through a hinge, such as the trunk lid. Be prepared to spend all day at it, though, as getting to the harness isn't easy. or 2. Connect a time domain reflectometer at the bulb socket and ping each wire separately. Calculate the distance from the socket to the first discontinuity for each wire. Measure the shortest distance of the two and expose the cable at that distance from the socket and repair the damage. Simple... :) It would be great if you could arrange to do the search while the light is on, but Murphy's Law assures that you won't get that lucky. Good luck! :-D
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
Actually, when I reconnected the battery a couple weeks ago, I thought I would check and found that the brake light was lit on the passenger's side with the car off. I tapped the brake pedal and looked again without starting the car or turning the ignition on and the light went out. I would think the switch would be the most suspect but to me I would think it would enable both of them not just one. It is about time to drive another car under that radiator cap ;)
Rocky <>< Recent Blog Post: Silverlight Domain Names up for grabs! Thinking about Silverlight? www.SilverlightCity.com
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That's actually funny! :laugh:
It is? :confused:
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If it was the switch then both the brake lights or all the other lights (tail lights, front side lights, etc.) would come on. Ergo, forget the switch (unless the other brake light is dead anyway).
Phil
The opinions expressed in this post are not necessarily those of the author, especially if you find them impolite, inaccurate or inflammatory.
Well, the light has to be getting power from *somewhere*, and the only thing between the light and the battery is one of four switches: 0) Emergency Flasher switch - not likely because these are used VERY rarely, so wear/tear shouldn't be an issue. 1) The headlight switch - on or off, and controls all lights, so I wouldn't think this is the problem. 2) The turn signal switch - operates one light at a time, but only in the switched-on position. This would be my second guess. 3) The brake light switch - because it's constantly turned on and off by mechanical means (pressing the brake pedal), and the light seems to come on by itself, it is probably this switch switch due to gravity working on a slightly worn brake pedal assembly. The car is, after all, almost 20 years old. It can't possibly be the wiring between the switches and the light because the light comes on. A wiring problem in the loom would prevent the light from working at all.
"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
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"...the staggering layers of obscenity in your statement make it a work of art on so many levels." - Jason Jystad, 10/26/2001 -
Hmmmm... It's been a while, but, 1. It's nearly 20 years old, and they didn't have all the electronic, computer-controlled whizbangs in them that make real diagnosis impossible. 2. It's intermittent. 3. It drains the battery overnight, which a single bulb should not do. Ergo: It's in the wiring harness, and probably involves more than one wire. I'd guess that abrasion has worn off the insulation on a couple of wires where the tail light harness makes a sharp bend around a metallic chassis component, but that's only a starting point. Some automotive wiring uses the quaint notion of wiring the hot side (positive) to each device and switching the negative to ground to turn them on. This causes some interesting sneak paths for current when something goes wrong. 1. Start at the brakelight; open it up and make note of the color of each of the wires. Expose the wiring from back to front as you work your way forward to the fuse block and visually inspect the wires for damage, especially where they go around corners or pass through a hinge, such as the trunk lid. Be prepared to spend all day at it, though, as getting to the harness isn't easy. or 2. Connect a time domain reflectometer at the bulb socket and ping each wire separately. Calculate the distance from the socket to the first discontinuity for each wire. Measure the shortest distance of the two and expose the cable at that distance from the socket and repair the damage. Simple... :) It would be great if you could arrange to do the search while the light is on, but Murphy's Law assures that you won't get that lucky. Good luck! :-D
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
Roger Wright wrote:
Some automotive wiring uses the quaint notion of wiring the hot side (positive) to each device and switching the negative to ground to turn them on.
Eeek! :~
Roger Wright wrote:
Connect a time domain reflectometer at the bulb socket and ping each wire separately.
Now, where did I leave my time domain reflectometer after fixing my bike's turn signals? ;P
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Rocky Moore wrote:
Any ideas?
Parking lights. Look in the owners manual how they get activated.
xacc.ide - now with TabsToSpaces support
IronScheme - 1.0 beta 2 - out now!
((lambda (x) `((lambda (x) ,x) ',x)) '`((lambda (x) ,x) ',x))Parking lights are turned on with the headlight switch.
"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
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"...the staggering layers of obscenity in your statement make it a work of art on so many levels." - Jason Jystad, 10/26/2001 -
Hmmmm... It's been a while, but, 1. It's nearly 20 years old, and they didn't have all the electronic, computer-controlled whizbangs in them that make real diagnosis impossible. 2. It's intermittent. 3. It drains the battery overnight, which a single bulb should not do. Ergo: It's in the wiring harness, and probably involves more than one wire. I'd guess that abrasion has worn off the insulation on a couple of wires where the tail light harness makes a sharp bend around a metallic chassis component, but that's only a starting point. Some automotive wiring uses the quaint notion of wiring the hot side (positive) to each device and switching the negative to ground to turn them on. This causes some interesting sneak paths for current when something goes wrong. 1. Start at the brakelight; open it up and make note of the color of each of the wires. Expose the wiring from back to front as you work your way forward to the fuse block and visually inspect the wires for damage, especially where they go around corners or pass through a hinge, such as the trunk lid. Be prepared to spend all day at it, though, as getting to the harness isn't easy. or 2. Connect a time domain reflectometer at the bulb socket and ping each wire separately. Calculate the distance from the socket to the first discontinuity for each wire. Measure the shortest distance of the two and expose the cable at that distance from the socket and repair the damage. Simple... :) It would be great if you could arrange to do the search while the light is on, but Murphy's Law assures that you won't get that lucky. Good luck! :-D
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
A better answer would be to take it to a mechanic and let them deal with it. :)
"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
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"...the staggering layers of obscenity in your statement make it a work of art on so many levels." - Jason Jystad, 10/26/2001 -
Actually, when I reconnected the battery a couple weeks ago, I thought I would check and found that the brake light was lit on the passenger's side with the car off. I tapped the brake pedal and looked again without starting the car or turning the ignition on and the light went out. I would think the switch would be the most suspect but to me I would think it would enable both of them not just one. It is about time to drive another car under that radiator cap ;)
Rocky <>< Recent Blog Post: Silverlight Domain Names up for grabs! Thinking about Silverlight? www.SilverlightCity.com
I have an old Jeep Cherokee that will do the same thing on occasion. There is normally a spring on the brake pedal that returns the pedal to the "normal" position pulling the pedal up into the nonbraking position. In my case the spring was old and tired and allowed the pedal to sag slightly making the switch. All that I did was made sure to lift the pedal slightly with my foot when I exited the vehicle...... sounds silly but saved me the hassle of trying to climb under the dashboard and try to replace some spring. I would suggest applying the brake pedal while the car is in park and then letting off. Check the light to see if it is lit, then try lifting the pedal with your foot and verify the light goes off. If that fixes the problem, you can check to see if the switch position can be adjusted, replace the spring, or teach them to lift the brake pedal. You may have to try quite a few times to get the pedal to sag enough to make the switch.... it sounds like an intermittent problem.
Uptight Ex-Military Republican married to a Commie Lib - How weird is that?
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Hmmmm... It's been a while, but, 1. It's nearly 20 years old, and they didn't have all the electronic, computer-controlled whizbangs in them that make real diagnosis impossible. 2. It's intermittent. 3. It drains the battery overnight, which a single bulb should not do. Ergo: It's in the wiring harness, and probably involves more than one wire. I'd guess that abrasion has worn off the insulation on a couple of wires where the tail light harness makes a sharp bend around a metallic chassis component, but that's only a starting point. Some automotive wiring uses the quaint notion of wiring the hot side (positive) to each device and switching the negative to ground to turn them on. This causes some interesting sneak paths for current when something goes wrong. 1. Start at the brakelight; open it up and make note of the color of each of the wires. Expose the wiring from back to front as you work your way forward to the fuse block and visually inspect the wires for damage, especially where they go around corners or pass through a hinge, such as the trunk lid. Be prepared to spend all day at it, though, as getting to the harness isn't easy. or 2. Connect a time domain reflectometer at the bulb socket and ping each wire separately. Calculate the distance from the socket to the first discontinuity for each wire. Measure the shortest distance of the two and expose the cable at that distance from the socket and repair the damage. Simple... :) It would be great if you could arrange to do the search while the light is on, but Murphy's Law assures that you won't get that lucky. Good luck! :-D
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
You need a transmission line plus the dieletric constant to calculate the propagation speed otherwise you will look in the wrong place for the break, it could even be the unterminated end. Oh, plus the characteristic impedance or you could get a launch reflection. Moi? Difficult? :rolleyes:
Visit http://www.notreadytogiveup.com/[^] and do something special today.
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It is? :confused:
I found it funny :)
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Do you work for Microsoft? :)
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
No, but I am enslaved by them.
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I have an old Jeep Cherokee that will do the same thing on occasion. There is normally a spring on the brake pedal that returns the pedal to the "normal" position pulling the pedal up into the nonbraking position. In my case the spring was old and tired and allowed the pedal to sag slightly making the switch. All that I did was made sure to lift the pedal slightly with my foot when I exited the vehicle...... sounds silly but saved me the hassle of trying to climb under the dashboard and try to replace some spring. I would suggest applying the brake pedal while the car is in park and then letting off. Check the light to see if it is lit, then try lifting the pedal with your foot and verify the light goes off. If that fixes the problem, you can check to see if the switch position can be adjusted, replace the spring, or teach them to lift the brake pedal. You may have to try quite a few times to get the pedal to sag enough to make the switch.... it sounds like an intermittent problem.
Uptight Ex-Military Republican married to a Commie Lib - How weird is that?
Actually, I checked today. The light was on again when I connected the battery, so I lifted the pedal and it was still on. Only when I pressed the pedal enough to kick both lights on did it finally go out when released. After awhile, the light comes back on again on that one side. Almost to the point to just run a flip switch on that brake light and have it triggered when the ignition comes on :)
Rocky <>< Recent Blog Post: Silverlight Domain Names up for grabs! Thinking about Silverlight? www.SilverlightCity.com
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A better answer would be to take it to a mechanic and let them deal with it. :)
"Why don't you tie a kerosene-soaked rag around your ankles so the ants won't climb up and eat your candy ass..." - Dale Earnhardt, 1997
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"...the staggering layers of obscenity in your statement make it a work of art on so many levels." - Jason Jystad, 10/26/2001Isn't that a lot like handing someone your credit card and after they ring it up, you ask "How much will that be?" :)
Rocky <>< Recent Blog Post: Silverlight Domain Names up for grabs! Thinking about Silverlight? www.SilverlightCity.com
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My mother's Cadillac (early 90's) has a tail or brake light that likes to come on while the car is parked and drains the battery completely overnight. It can go days without happen, then presto, the batter is dead. Found out once when someone called and said the tail light was on and found that just the right side tail light (or brake like don't remember which) would come on for no known reason. Anyone heard of such a thing? The lights all work like normal, but this one light likes to come on at will when the car is off and parked. She cannot really be connecting and disconnecting the battery every time she uses the car, but do not want to take it in and see a huge bill without any results. Any ideas?
Rocky <>< Recent Blog Post: Silverlight Domain Names up for grabs! Thinking about Silverlight? www.SilverlightCity.com
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My mother's Cadillac (early 90's) has a tail or brake light that likes to come on while the car is parked and drains the battery completely overnight. It can go days without happen, then presto, the batter is dead. Found out once when someone called and said the tail light was on and found that just the right side tail light (or brake like don't remember which) would come on for no known reason. Anyone heard of such a thing? The lights all work like normal, but this one light likes to come on at will when the car is off and parked. She cannot really be connecting and disconnecting the battery every time she uses the car, but do not want to take it in and see a huge bill without any results. Any ideas?
Rocky <>< Recent Blog Post: Silverlight Domain Names up for grabs! Thinking about Silverlight? www.SilverlightCity.com
I'll work backward; many cars (most?) have a brake/transmission interlock. You cannot put the car into gear unless the brake pedal is pressed. The relay for this is often connected to the brake light. When this relay goes bad, you can't put the car into gear. What if this relay can go bad in a different way? Thus it may not be total chance, but rather how the car was put into park.
Anyone who thinks he has a better idea of what's good for people than people do is a swine. - P.J. O'Rourke
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My mother's Cadillac (early 90's) has a tail or brake light that likes to come on while the car is parked and drains the battery completely overnight. It can go days without happen, then presto, the batter is dead. Found out once when someone called and said the tail light was on and found that just the right side tail light (or brake like don't remember which) would come on for no known reason. Anyone heard of such a thing? The lights all work like normal, but this one light likes to come on at will when the car is off and parked. She cannot really be connecting and disconnecting the battery every time she uses the car, but do not want to take it in and see a huge bill without any results. Any ideas?
Rocky <>< Recent Blog Post: Silverlight Domain Names up for grabs! Thinking about Silverlight? www.SilverlightCity.com
You might try checking the brake light switch, I had one fail one time that would do exactly what you are saying. It was a partial short, and would drain the battery with no apparent light coming from the rear lamps. Changing the switch solved the problem, finding it involved pulling the plug off the switch mounted on the master cylinder, and seeing the meter needle go to zero. The brake and rear lights make the return circuit through the metal frame of the vehicle, with the voltage being supplied throught the wires routed to them through the body, after going through the switches, meters, fuses, etc. You can buy a haynes manual with a wiring diagram from an auto parts store that will show you how everything is routed, etc. Good luck
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Actually, when I reconnected the battery a couple weeks ago, I thought I would check and found that the brake light was lit on the passenger's side with the car off. I tapped the brake pedal and looked again without starting the car or turning the ignition on and the light went out. I would think the switch would be the most suspect but to me I would think it would enable both of them not just one. It is about time to drive another car under that radiator cap ;)
Rocky <>< Recent Blog Post: Silverlight Domain Names up for grabs! Thinking about Silverlight? www.SilverlightCity.com
It's a long shot, I know, and I wouldn't expect even a US car maker could be so dumb, but might they have terminated both brake lights at the switch? If so, a loose connection at the switch could cause the problem in one light, but not the other. If only one wire is terminated at the switch there's no way the switch could be at fault.
"A Journey of a Thousand Rest Stops Begins with a Single Movement"
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My mother's Cadillac (early 90's) has a tail or brake light that likes to come on while the car is parked and drains the battery completely overnight. It can go days without happen, then presto, the batter is dead. Found out once when someone called and said the tail light was on and found that just the right side tail light (or brake like don't remember which) would come on for no known reason. Anyone heard of such a thing? The lights all work like normal, but this one light likes to come on at will when the car is off and parked. She cannot really be connecting and disconnecting the battery every time she uses the car, but do not want to take it in and see a huge bill without any results. Any ideas?
Rocky <>< Recent Blog Post: Silverlight Domain Names up for grabs! Thinking about Silverlight? www.SilverlightCity.com
I do know that European cars have an additional "Park" lock. You have to twist the ignition anticlockwise twice to operate this mode and this leaves the parking lights on. So if you just want to switch off, you only turn the ignition anticlockwise once.
