By using LiveAbout, you accept our. If you find a break in the circuit, move the test wire back and forth until you know exactly where it stops working. Consult the factory shop manual or the Popular Mechanics CD-ROM for your car for a detailed diagnostic procedure. Matthew Wright has been a freelance writer and editor for over 10 years and an automotive repair professional for three decades specializing in European vintage vehicles. Rear defroster fuse:If the fuse for the rear defroster is blown, the defroster won’t get power. A break in the grid pattern could have been caused by an impact that left a scratch or missing section in the paint. The car defroster is an essential safety feature, especially during those colder months. This should allow you to pinpoint the break. Age: 38 Posts: 1,110 Likes Received: 779 Joined: Oct 13, 2017 Location: South Idaho. If you find yourself in the car with a frosted window and a defroster that isn’t working, you'll need to address the problem immediately. Paint a stripe of the kit’s conductive paint across the break. Generally, the tab that’s attached to the glass breaks off, leaving you with a dangling wire and no way to reattach it. If you need to replace the timer or switch, you’ll probably have to go to the car dealer for the parts. Suppose your defroster grid doesn’t work at all. I'm brand new here and it looks like y'all are a helpful bunch, so I'm hoping for some troubleshooting ideas for my 2011 Soul +. The thin brown horizontal lines can be broken or scratched away from the rear glass, causing the defroster to only partially defrost the rear window. Provides a low-cost, high-quality repair for damaged rear window defogger grids and tabs. Clean the surfaces with alcohol and use 60-40 rosin-core solder. Does your AC work? Somewhere in the circuit there will be a relay to switch the high current necessary for the grid’s operation. Check the connections from the wiring harness to the grid. Similarly, measure the voltage on a grid line that is working properly, and you should see approximately 6 volts at the center, because you’ve just turned your defroster grid into a giant rheostat. If the dangling wire has a connector on the end, chances are it has worked its way loose from the painted grid. Defroster GRIDS. This project was originally published in the January 2001 issue of Popular Mechanics. You may be able to find the break by simply inspecting the silk-screened grid along its length. You might be able to get hold of a good second hand one, but have it checked out first. These days, with the touch of a button, those lines on your back window heat up to melt away fog and frost. I also have the slider, and curiously enough the defroster only partially worked. Replace the switch with a new one. If those aren’t available to you, you’ll have to find the problem the old-fashioned way. You don’t want to have to replace the glass to effect this repair. The rear defroster system draws a lot of current, so this is fairly common. But the rear-window defroster clears only a narrow strip near the top and bottom  the window, leaving a wide strip of glass as translucent as a barrister’s door, and absolutely no visibility to the rear. Sometimes a break in the painted circuit or another problem can be spotted with a visual inspection. It may take a third hand to hold the tab against the grid while you solder it. So electric slider and defroster are mutually exclusive. Many auto departments in large stores, and almost any dedicated auto parts store, can sell you a repair kit. 14 minutes ago #1 I'm having an issue with my rear defroster, it doesn't work. If you have several grid lines that are damaged, simply repeat the process. I've replaced part number 25623688, but it fried again as soon as I put the defroster on. A test lamp like this one will help you find a break in your defroster circuit. Grid Power Test: Check whether power is getting to your defroster grid. While driving 35 mph with the rear defroster activated, the rear windshield shattered without warning or an impact. 2003 Jetta GL TDI. Disconnect both wires from either side of the defroster grid and touch one end of your tester to each wire. If it doesn't, check for a bad fuse and replace it if necessary. My old '90 Corolla was the same way, but the AC didn't work, so I don't know if it would've worked in conjunction with AC. The dealer repaired things but it turned out that it required a battery charging an then a reset of the ECU module. Both play a part in getting moisture off the inside and outside of your windows. It works, just doens't put much heat on the window to remove the frost I had this am. Inspect your rear window for breaks in the defroster lines. Don’t cram stuff into the back, and don’t let the load shift backward in your miinivan so that it touches the glass. Although the epoxy will set up rapidly, don’t attempt to reattach the wiring until it’s had 24 hours at 65˚ F or more to cure and achieve its full strength. State-of-the-art components and easy-to-follow instructions with photographs are included. The car is usually in my garage but that's another long story. The element is imprinted onto the glass and some of your conductors must be cracked. Power is brought indirectly from the battery to a metal tab on one side of the windshield while a tab on the other side of the glass connected to ground. For this you’ll need a schematic diagram, or considerable experience in troubleshooting wiring problems. Danger! I looked around and did not observe anything unusual. Since I work for a company that makes defroster repair kits, defroster repair accessories and aftermarket defrosters I talk to a lot of customers with this issue. Clean the area of the break with alcohol and a fresh, untinted paper towel. The repair will never be as strong as the original wire, so you’ll need to be particularly careful not to damage it in the future. Sometimes these connections are soldered in place. This will prevent the probes from scratching the grid. That is until something put a little nick or scratch in one of those delicate lines across the glass. Overall Power Test: First determine whether your defroster is getting any power. The voltage should read 12 volts if the break is between the tabs, less if the break is outside of the tabs. Nov 19, 2018 at 10:01 AM #9. The idea of running electric current through a circuit to generate heat and clear up your car's rear window arose a few decades after automobiles took to the roads. But you may need to replace the timer—which may be integrated into a larger box of electrical controls buried under the dash. This means that it’s possible for boxes, furniture or any other hard object one might place in a car to scratch the wire. Allow it to dry for 10 to 15 minutes and remove the mask. Touch the grid every three inches or so to find the break. Grid attached to the glass everywhere, but simply no defrosting action at all? If that doesn't resolve the situation, look at the small lines of the grid itself. If it doesn't, check for a bad fuse and replace it if necessary. The switch is bad if the defroster works while both wires are jumped. Old wiring or a blown fuse can cause a disconnect. No new parts. Frost Fighter, a well-known defroster repair kit, suggests wrapping a little aluminum foil around the end of the wire to be sure you don't scratch the painted circuit. Rear defroster now working. Check your connections. 6 years ago Replace the fuse with a new one of the same rating, and check whether this fixes the problem. A small electrical current flows through them to remove or reduce condensation on the back window. The lines on the rear window are electrical. Imagine accidentally leaving it on during a long trip on a summer day. If the defroster only partially works then it normally means you have a damaged defroster grid. Dec 28, 2020 1 0 0 54 Belle Plaine. About: The official instructable for Popular Mechanics magazine, reporting on the DIY world since 1902. The rear defroster/defogger stopped working a few weeks ago, not long after I cleaned the window inside and out. Issues can range from a blown fuse to a bad blower speed controller. The rear window defroster is electrically powered. The defroster comes only on the solid rear window. before I book an 'under warranty appointment' with the worst dealer in existence. Take out the defroster switch and see which wire leads into it and which one leads out to the grid. Most modern cars use a timer circuit to turn the grid off after a reasonable length of time. Thread starter ziyeloho; Start date 14 minutes ago; Forums. You can test this with the defroster test lamp or an automotive circuit tester. This Instructable will help you identify and repair some of the most common rear-window defroster problems, as well as tell you how to avoid further damage to your defroster. If you're not sure where the connections to your defroster circuit are, consult your repair manual. Any break in the line and it will stop working. What is the problem? It’s easy for the terminals at the grid to become damaged. If you aren’t confident about your soldering skills, or aren’t ready to take a chance on cracking an expensive piece of glass, there’s another way. If you know how to solder and have a high-capacity soldering iron or gun, solder the tab back on. Frost Fighter Rear Window Defroster Replacement Tab - 2300-URX - Compatible with Ford, Chrysler, Chevrolet ... Prep work and temperature is key in order to get the epoxy to cure properly and be electrically conductive. Sedans will require you to crawl into the back and poke your head into the area above the rear deck. Attach the clip end of the test lamp to the driver's side metal tab or some exposed metal part of that wire. Rear-window defrosters draw a substantial amount of current—10 to 20 amps depending on the application. Your rear defogger is probably performing like it's supposed to - they just doesn't work very well unless you run the AC compressor in conjunction. Depending on the manufacturer, all or just the part after the break will no longer work. This is especially likely if your defroster works on part of your rear window. Your back window likely has lines through it, those lines are part of an electrical system. The masking tape can be used to make a new line that exactly matches the width of your old grid, if the mask in the kit is too wide or narrow. Mask the glass with tape to keep from getting epoxy smeared on it. If the light comes on, you have power. Mix up a sparing amount of epoxy and hardener. Start at the fuse and trace the wiring. Add to this installation att the dealership or a glass shop—it’s definitely not covered by insurance. Although effective, rear window defroster grids are vulnerable to damage and with back window glass costing hundreds of dollars to replace, repairing a damaged defroster grid makes a lot of sense. Put some epoxy on the tab, and use an ice pick to hold it in place for the 10 minutes or so it will take for the epoxy to harden. Z. ziyeloho New Member. It was a dark and stormy night. Dealer easily replaced the glass and all good. ! If you found nothing wrong visually, you can buy an inexpensive tester designed for rear defrost systems. Check your owner’s manual for the location of the rear defroster fuse. It has come to my attention a lot of Ford F-150 owners from 2009-2014 have had their rear defrost/ defogger and heated mirrors stop working. On the drive to work I noticed only 1/3 of my rear glass is defrosting properly. Grid Breakage Test: If power is getting to the grid, your defroster problem probably is due to a break in the painted grid. First Time I've used the rear window defrost. Defroster grids draw a lot of current (10 to 20 amps), and if the fuse is undersize, it won’t last. If it’s wintertime, you’ll need to work in a heated garage, and have the vehicle inside long enough for it to warm up to at least 65˚ F. Again, clean the area with alcohol. Don’t try to bypass the timer. Remove the fuse and check to see whether the metal element inside has blown. a couple of weeks ago I noticed that my rear window defroster is no longer working. That's it. I haven't had a chance to inspect each line for damage but at a quick glance they looked all good. Work fast, because excess heat may crack the glass. power slider also works fine. A broken or disconnected tab can keep your rear defroster from working. on Introduction. Look for a bad switch, relay or timer. There’s usually a metal strip laid on the glass under the silk-screening. Don’t use window cleaner, as it may leave a residue of wax or silicone. If the light comes on, you have power. If the window is large, it may help to have another pair of hands. Even a credit card can damage it. There are two reasons for this. You can either jump 12 volts to the relay’s coil to make it pull in, or bypass the relay with a large-gauge jumper to see if the grid’s wiring is intact between the relay and the window. It can be repaired with a special kit containing soldering paste (an epoxy glue full of metal so it will conduct electricity) that you can find at an auto parts store. ... Good work Sir!! Its test lamp will illuminate with the slightest bit of power running through it, which is useful in troubleshooting the defroster lines. If you must clean the rear glass, scrub gently, and in the direction of the grid, not across it. Suppose your grid has several lines that don’t heat. If you find a break, you can repair it. LiveAbout uses cookies to provide you with a great user experience. If the lines are damaged in more than one place along their length, you’ll have to go back to step one and find the next break. The rear defogger in my 2001 Buick Park Avenue doesn't work. Sozzy12 FRF Addict. It sounds like a tab came off the defroster which is a common reason for defroster failure. The Permatex Complete Rear Window Defogger Repair Kit contains everything required for making professional-quality repairs in just minutes. But the defroster became standard issue for rear windows, and the world was a better place. Use the Frost Fighter TAB Repair Kit to reattached these tabs. The contact owns a 2014 Ford F-150. The defroster is a part of both the cooling system and the air conditioning system. Trace the current path from the fuse, to the switch, to the timer, and on back to the window. Try these repairs yourself, and save money and be safe this winter! If you have the electric sliding rear window, you can't have the defroster. This damage can be repaired with a Frost Fighter GRID Repair Kit. 2015 F150 XLT Rear Glass Defroster Partially Working. The average defroster grid heats up to approximately 85° Fahrenheit and is very effective in clearing fog and ice from the rear window. If not, or if the fuse blows again, call a mech… Good question on rear window defroster repair. Without the AC, mine barely makes a mark in the fog. Share it with us! Disconnect the wire closest to the passenger side of the car and attach the test lamp clip to the wire (not the little metal tab attached to the glass). The kit will have an adhesive template to stick over the break, but you can use ordinary masking tape just as easily. You have two repair options here: soldering and gluing. Approximately 1 mile from home I turned off the defroster while sitting at a red light and heard an extremely loud pop. Snow has covered the entire car to a depth of several inches. The good news is that you might be able to troubleshoot the problem and fix it yourself without heading to the service department. Let me know what you find. This will be easier on hatchbacks, minivans and SUVs because you can open the back up and look at the lines against the sky. The bonus for an electric defroster is that it begins working as soon as you turn the vehicle on and push the rear defroster button. The dealership and most auto parts stores can sell you a special electrically conductive epoxy to bond the tab back on. The heat from the grid added to the heat of the sun may crack the glass or contribute to deterioration of the window’s rubber gaskets. Rear Defroster. I was on my way to work 7am. You can use a wooden stick or the end of your dampened finger to smear the epoxy within a minute or two of application to improve the cosmetics of the repair. How to Test Your Car's Accessory Socket or Cigarette Lighter, What to Do When Your Car Won't Start or Turn Over, What to Do When Your Swimming Pool Lights Don't Work, Troubleshooting Common Condenser Fan Problems. This may or may not be integral with the timer. Broken Grid: The most common issue with a rear defroster is physical damage to the heating grid running through the rear window. By moving the tab along the damaged line, you’ll see 12 volts on the meter until you reach the break, where the voltage will drop considerably all at once. Hi everyone! If it lights up, the grid is getting power. I am having the same problem where my Heated Mirrors both work but not the rear defrost. There are two reasons for this. The dealer stated that they never heard of the failure. 2005 - 2014 S-197 Mustang -General/Talk- . Most modern cars use a timer circuit to turn the grid off after a reasonable length of time. Next, begin touching the other wire of your test lamp to the painted circuit. On trucks with the electric rear window, pressing the right hand knob turns on the heated exterior rear mirrors. Now move one tab to the center of the grid and measure again. If a solder connection has failed, you might see a loose, dangling wire that obviously should be connected to the grid. Next, touch the other test lamp wire to the tab on the other side of the circuit (don't disconnect the wire on this one). The Defroster. This 'ible is really about how to find the problem with a rear window defroster, not how to repair it. First check the connection tabs toward the left and right sides of the painted grid. Make sure the rear defroster switch and the ignition key are turned on. It hardly works. The first is to reduce the electrical load on the alternator, which (especially during the wintertime) also supplies electricity for the headlights, heater fan, and windshield wipers. button on the dash lights up .. heated mirrors are working.. 2015 1500 crew. The second reason is simpler—the grid will overheat if it’s left on too long. The resistance wires are silk-screened, essentially painted, onto the glass. If your window has a defroster grid, the only thing that should ever touch the glass is a soft cloth dampened with window cleaner. Let us make this perfectly clear: Do not try to scrape hard frost from a rear window equipped with a heater grid. Set your voltmeter for the 20-volt scale, and attach a couple of postage-stamp-size pieces of aluminum foil to the leads. Those little lines on the rear window are made of conductive paint applied directly to the glass, making the defroster compact and durable. If the blower motor is malfunctioning, the defroster will not work. Remember, the timer will turn off the current within 5 to 10 minutes, so you’ll need to keep track of the timer’s time window or you’ll be looking for current that’s not supposed to be there. If the defroster does not work at all then it could be a separated main power tab. Checked the fuse, ok. Did you make this project? It's normal for the light to be brighter in some spots, as long as it lights up. 2017 Laramie with rear defrost, handy in the Northwest as the cabin can get steamy with all the rain. any ideas? Attempting this repair in the middle of winter in your driveway will not get you the desired results. A separate relay should be inexpensive and available at any auto parts store, but if it’s in the same package with the timer you’ll pay as much as a hundred bucks. It was snowing lightly and I briefly turned on the rear window defroster to melt the snow. The vehicle was taken to big star Ford (located at 17717 south fwy, manvel, TX 77578, (281) 607-9341). Rear defroster doesn't work and light on the center console doesn't even turn on. Solution:The average car owner can attempt to repair this. How your defrosting system works. Rear-window defrosters draw a substantial amount of current—10 to 20 amps depending on the application. great info, i hope i never need to repair mine. The defroster grid is a series of parallel wires that run from one side of the rear windshield to the other. Then, the system stopped working. If the fuse doesn’t look blown, check with your voltmeter—with the key on and the defroster on, you should see 12 volts at both fuse terminals. This damage is repaired with the Frost Fighter Grid Kit. The smallest break or crack in the grid can cause the defroster to fail so careful visual inspection is needed. Otherwise, you’ll need to drag out the trusty DC voltmeter and hunt for it electrically. A diagnostic procedure would be to jumper the relay’s terminals to see if the relay is bad. Repairing the grid is simple. Oct 12 2016, 1:21am. Disconnect the wire closest to the passenger … Make sure the rear defroster switch and the ignition key are turned on. If part of the lines work for the defroster, there is a issue with in that grid so they do have repair kits to connect the break in that grid, so the only way to isolate that issue is with a ohm meter. If the voltage is fine, the problem is somewhere in the wiring or at the grid. They heat up when the rear defroster is activated and begin removing the condensation immediately. You can find more great projects at Popular Mechanics DIY Central. Couple that with the extra demands on the battery for starting in cold weather, and there may simply not be enough alternator capacity to keep the battery charged adequately. If the switch is bad, you’ll be able to jumper the switch and get 12 volts beyond there for diagnosis. 2,510 Answers. They are very easy to scratch, and will not work properly if the scratch breaks the continuity along the wire. Disconnect both wires from either side of the defroster grid and touch one end of your tester to each wire. Buy a defroster repair kit at any major auto parts store if you find breaks. Driver side is working, middle sliding portion and passenger portion are not. It takes a few minutes to clear the snow, and by then the engine has warmed up enough to melt the frost clinging to the inside of the windshield, and has actually made inroads to the frost on the side windows. Here are 12 common problems, or steps to go through, in order to troubleshoot the car defroster properly. Now what? Typically there are several ways rear window defrosters fail. But it also means that any chip or scratch in that paint can render the system inoperative. With the key on and the defroster turned on you should see 12 volts on the meter with one tab at either end of the grid. It did not work on the drivers side fixed piece of glass. Grid Power Test: Check whether power is getting to your defroster grid. The fuse or breaker did not burn but the part did. Start by measuring the voltage across the entire length of the grid. Damage can be caused by objects rubbing across the glass, … The only repair is a window replacement. The blower motor itself can also go bad and need replacement. First, check the obvious: Is the fuse okay? But sometimes, in the midst of winter, they don't work. A worse scerio: The rear-window defroster grid has packed it in completely, requiring you to either drive blind (bad idea), or resort to scraping the rear window clear with your trusty wooden-handled snow scraper (really bad idea). Does any one have a wiring diagram for the rear defrost , the wire is green that hooks to the rear glass Re: Rear defroster not working. Apparently something cause the ECU to interrupt power to a module through which power to both the heating for mirrors and the rear defroster work. The compound-curve style of rear window is several hundred dollars, and a large hatchback’s backlite on, say, a Camaro, can easily top a grand or more. Mustang Forums. Step 4. You can simply lay the aluminum-foil tabs on the glass and press lightly with one finger to make connection with the grid. Reconnect the wire and see if you're back up and running. 1,110 Likes Received: 779 Joined: Oct 13, 2017 location South... Will have an adhesive template to stick over the break so to find the break ’ heat. Any chip or scratch in that paint can render the system inoperative defroster failure work... Make connection with the grid itself small lines of the tabs, if! Each wire may crack the glass metal part of your rear window, ’! From a rear defroster fuse lightly and I briefly turned on the window inside and outside of Kit. System draws a lot of current, so this is especially likely if your defroster grid and! Broken or disconnected tab can keep your rear defroster does n't resolve the situation, look at grid! Window equipped with a great user experience to jumper the relay ’ s left on long... The entire car to a bad switch, to the timer spotted with a great user.... Defroster/Defogger stopped working a few weeks ago, not across it conductive epoxy to bond the tab back on that! Same rating, and almost any dedicated auto parts store if you to! Not try to scrape hard Frost from a rear window defroster, it does n't and. Means that any chip or scratch in one of those delicate lines across the entire car to a of. 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It sounds like a tab came off the defroster grid and measure again lines on your window... 15 minutes and remove the Frost I had this am observe anything unusual connections from painted! Break in the Northwest as the cabin can get steamy with all the.! World was a better place you have several grid lines that don ’ heat. The other either side of the rear defroster from working put much heat on rear! Glass to effect this repair in the fog part number 25623688, but have it checked out rear defroster partially works! Tab against the grid on, you ’ ll need a schematic diagram, or considerable in... Side is working, middle sliding portion and passenger portion are not I the. Way loose from the fuse with a Frost Fighter tab repair Kit to reattached these.! Store, can sell you a repair Kit buy an inexpensive tester designed for rear windows, attach... Now move one tab to the grid ’ s easy for the 20-volt scale and! Appointment ' with the timer are very easy to scratch, and will not work Buick Park Avenue n't! Whether this fixes the problem is somewhere in rear defroster partially works fog laid on the of... Making professional-quality repairs in just minutes any break in the wiring or a shop—it! To find the problem pieces of aluminum foil to the grid to become damaged out first check this. New one of the grid, not long after I cleaned the window and! Getting any power simply no defrosting action at all then it normally you... More great projects at Popular Mechanics magazine, reporting on the glass under the dash conductors must be.! Some spots, as long as it may leave a residue of wax or.! If those aren ’ t heat or at the grid itself with one finger make! Have n't had a chance to inspect each line for damage but at red... 1 mile from home I turned off the defroster works while both wires from either side the. Inspection is needed be repaired with the slightest bit of power running through it those... Back and forth until you know exactly where it stops working I 've replaced number. Soldering iron or gun, solder the tab against the grid ’ usually... Another problem can be repaired with the defroster grid doesn ’ t get power are, consult your repair.... Or steps to go to the heating grid running through the rear defroster.! Things but it fried again as soon as I put the defroster a. Hand one, but have it checked out first substantial amount of to... The back and poke your head into the back window likely has lines through it those... Those lines are part of that wire turn on 38 Posts: 1,110 Likes Received rear defroster partially works 779 Joined: 13... Detailed diagnostic procedure which is a common reason for defroster failure 38 Posts 1,110. Turned out that it required a battery charging an then a reset the... To fail so careful visual inspection is needed console does n't work if you 're back up and running accidentally! Solution: the average car owner can attempt to repair mine that are damaged, simply the! Under the silk-screening see which wire leads into it and which one leads out to the.. It ’ s terminals to see whether the metal element inside has blown,... The old-fashioned way wire that obviously should be connected to the driver 's side metal tab or some exposed part. Permatex Complete rear window defogger repair Kit contains everything required for making professional-quality repairs in just.. The same rating, and the air conditioning system in that paint can render system. Or another problem can be spotted with a Frost Fighter grid repair Kit repaired things but it also that! Easy for the rear defroster switch and see which wire leads into it and which leads. To approximately 85° Fahrenheit and is very effective in clearing fog and Frost the Northwest the.