Rear defrost does not work

Does any one know how to figure out if the defrost switch is bad or if it is an element problem?

I have checked all the fuses inside and out. There are all good, and my power seat works, :).

I press the button I can hear the switch click, but no light.

I was wondering if there is a way to measure the switch and see if it is bad. I am told you have to replace the full control panel for just that one switch, that sucks.

I don't want to order an expensive part and find out the problem is some where else, like the element. The care does not appear to ever have window tint. Even on my 99 when I removed the tint the element was still good, just took twice as long.

The only way I know to replace a faulty element is spend about 350 bucks on new glass.

before any one points out the obvious, i have absolutely the worst luck at local u-pull its. One is owned by LKQ the ebay bandits and others, well, i never seem to find any F-bodies, or at least none with parts on them, :). It seems the local salvage yards pull the hot items fist and sell them from the counter, ouch, or worse ebay them. Still I would rather drop 350 on new professionally installed and warrantied glass than a u-pull failure, :).

Is this car new to you?

Start with the basics: Check your fuse, if you can get to the back of the switch probe it for power with a test meter, check any ground connections, look at your wiring to your hatch, check the connections to the grid, and then look your grid over for any breaks. Could be something simple...

The wires broken where the rear window defrost grid gets its power from. They broke right near the gas shocks that hold the rear window up. They flex there as the window does up and down and eventually broke.

the grids can be repaired and so can the wire that is connected to it. 3M makes the glue and repair kit. You may not be able to find it on their website, so I would suggest calling them.

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Originally Posted by FORD RECOVERY EXPERT

Is this car new to you?

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yep. The 99 z28 is off to a new home. When i was looking over the 02 z28 I never thought to press the defrost button. I felt like such a big dufuss. I was looking at all the things i remember about the 99 and never once thought of the defrost. I checked the speakers, A/C, blah blah... I felt so silly. I never rolled the windows down either. First day home I had the joy of replacing the driver window motor, DOH.

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Originally Posted by pajeff02

Start with the basics: Check your fuse, if you can get to the back of the switch probe it for power with a test meter, check any ground connections, look at your wiring to your hatch, check the connections to the grid, and then look your grid over for any breaks. Could be something simple...

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Fuses are good. Any specific voltage or resistance I should measure? What wires are important? I'm sure there will be many colors back there.

I will take a long look at the section on the glass that makes the wire and element connection.

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Originally Posted by 9t8z28

the grids can be repaired and so can the wire that is connected to it. 3M makes the glue and repair kit. You may not be able to find it on their website, so I would suggest calling them.

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Huh, i didn't know that. I wish I did I would have repaired my old 99 z28. I had like a 2.5 to 1 on time after stripping the tint off, lol...

As far as I could tell the element lines look good. I need to go check out the spot where the wires meet the elements in the upper corner though.

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Originally Posted by thearborbarber

The wires broken where the rear window defrost grid gets its power from. They broke right near the gas shocks that hold the rear window up. They flex there as the window does up and down and eventually broke.

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do you know id this is repairable? I am guessing it is.

Just a little cutting and splicing, might want to extend the wires an inch or two to prevent the same problem from happening again...
J

the wires look ok to me. I looks like the solder on the window is good. The wires don't look bent or mangled. I'm not real sure what a broken wire back there would look like. But everything appears ok, that is without pulling off all the trim panels.

Would the defrost light still light up if the real wire(s) were broken?

What you can do is pull the wires off the grid, and measure for 12 volts across them with a test light or multimeter. Gives the wires a jiggle back there as well, wires can break and not look like it on the outside.

You say the light doesn't work? Might be as stupid as that, won;t be the only time I heard of a burnt out light causing issues.

ok tx. I will try to be gentle tomorrow. I will take my multi meter and see if i can measure 12V across the two.

I take if I don't get 12V the switch is bad. What would you try next if I measure 12V? I'm thinking this is not likely, since a working switch would complete the circuit. If i measure 12V across the wires....well that is a working circuit too, right....

Wouldn't I be able to measure voltage with out removing the wires?

my wife's 04 sebring read 10.49V when on. Mine reads a big fat zero.

Guess I am out about 150 bucks for a new switch.

Yup the switch going bad is common prob in our cars, well @ least that is what I was told by the tech when I had mine replaced under warranty..

not nessisarlly, there is a circuit breaker to check as well. first off, see it its hot, if not see if you get 12V there. it also powers the seats.

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Originally Posted by kool-aide

my wife's 04 sebring read 10.49V when on. Mine reads a big fat zero.

Guess I am out about 150 bucks for a new switch.

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Try here: http://tacreationsusa.com/defogger_switches.htm

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Originally Posted by Orcus79

not nessisarlly, there is a circuit breaker to check as well. first off, see it its hot, if not see if you get 12V there. it also powers the seats.

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all of the fuses are good, and the seat works.

I may pull the dash after work one day and see what it looks like.

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Originally Posted by pajeff02

Try here: http://tacreationsusa.com/defogger_switches.htm

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thank you. i'm not made of money but sometimes paying for a pulled part may not be worth it. I am going to see if i can get lucky at a local salvage yard. I just hate them because they pull all the glass, typically, and the cars sit out to rot under the hot sun and rain.

who knows, maybe i will get lucky and find a nice used pull part, :).

anything can happen.

Do you have 12v going into the switch?
J

not sure. I only measured at the glass last night. I haven't tried it today. I will have to wait until tomorrow. I will pull the panel off and poke around with the meter. I wish I had a meter with the audible continuity feature. Makes it easier than constantly looking over for Ohms when your fumbling around the wires.

well i guess something that is part of the switch is bad. I pulled the plug and got about 12V.

guess i will be salvage yard hunting or saving my money. i was wrong on the new part, i found it for $105 not $150, makes it a little better, :).

i was very disappoint to see the right side A/C wire harness was super short. What a real pain in the butt.

is there a way to tell if the element stuff on the rear window is bad? I'm still trying to diagnose why my rear defrost does not work.

All fuses are good. I have already tried a used part, claimed to be working when on car. Trial and error with used parts can lead to dead ends. Trial and error with new parts is 100 bucks, tax, and shipping. That is costly.

I would like to try and find the cause by diagnosing it.

Last time i used my meter on the car i had no voltage at the rear window as measured off the metal connectors.

Is there a way to use a volt meter to verify where the problem is?

thanks

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Originally Posted by kool-aide

is there a way to tell if the element stuff on the rear window is bad? I'm still trying to diagnose why my rear defrost does not work.

All fuses are good. I have already tried a used part, claimed to be working when on car. Trial and error with used parts can lead to dead ends. Trial and error with new parts is 100 bucks, tax, and shipping. That is costly.

I would like to try and find the cause by diagnosing it.

Last time i used my meter on the car i had no voltage at the rear window as measured off the metal connectors.

Is there a way to use a volt meter to verify where the problem is?

thanks

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You can always start at the switch and work your way back. Do you have access to a wiring diagram for your car?

i haven't checked the switch to the panel i just put in. i can do that today. the last time i did this was on the original switch. all i could get to was the wire harness at the back of the switch.

any chance someone knows which wire is the ground?

i pulled the rear hatch trim off and the wiring back there looks fine.

has any one ever heard of the element on the glass going bad? i would think this is pretty rare. even after a bad tint removal on my 99 i still had a working element, took twice as long though.

I juuuust fixed a similar problem on my 02 ws6. Mine was the switch, I didn't even test anything else, looked at the rear window and the wires weren't broken, so I ordered the switch right away, had same happen before.

bad news: you need to buy the whole panel rather than just the switch you need and i hear it's a couple of hundred dollars!

Good news, I got mine from youngsfbody.com for under 30 without the knobs! It took only a few minutes to replace.

TIP! just pop the switch out of the new panel and replace that, rather than having to disconnect the whole panel. the faceplate pops off easy.

Good luck!
--alex

i will check out the site. i didn't know they had them. was it used or new?

i already replaced mine with a "u-pull" it. it was said to be in working condition. well that's why i don't gamble, :), i would lose my life savings, lol...

well i am not sure what wires go where but i tried to measure a bunch of combinations.

I have Black -> B
I have Brown -> Br
I have Purple -> P
I have Orange -> O

that is the order they are in from one direction as they are adjacent to each other. I only measured voltage.

Car off - did not push defrost switch

B to Br = < 1V
B to P = < -1V
B to O = 11.89

P to O = 11.90V

Br to P = -.23V
Br to O = 11.53V


Car on, running - did not push defrost switch

B to Br = 13.95V
B to P = < -1V
B to O = 14.00

P to O = 13.95V

Br to P = -13.84V
Br to O = 0V

Car ignition on, not running - pushing switch on/off, on/off as best i could

B to Br = 13.67V - i think the car may have been running here too
B to P = < -1V
B to O = ~12V - had car running for this ~13.79V

P to O = did not measure, gave up, :)

Br to P = -12.12V
Br to O = 0V

i have no idea what combinations should be zero and what should be 12V. I am assuming the negatives are reverse measurements. I held the black lead to the first color in my listings at all times, Black, or Brown, or Purple.

I have a 00Ta an if I put the rear defrost on it over heats the relay in my fuse box and then my seat dosn't move!!!!:cry2:

i have heard that. the reset-able fuse. my seat works all the time and all of my fuses are good.

If your car utilizes the same switch as our Firebird, I can PM you the wire diagram and pinpoint tests to diagnose the defroster.

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Originally Posted by pajeff02

If your car utilizes the same switch as our Firebird, I can PM you the wire diagram and pinpoint tests to diagnose the defroster.

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I'm not sure it do Jeff. Ours is in the lower left hand corner of the heat control face.. Is round.

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Originally Posted by Smittro

I'm not sure it do Jeff. Ours is in the lower left hand corner of the heat control face.. Is round.

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I can't even remember what my switch looks like... or where it is mounted. Just not one of those critical things for a summer only driver.

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Originally Posted by pajeff02

I can't even remember what my switch looks like... or where it is mounted. Just not one of those critical things for a summer only driver.

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I have'nt seen a car like yours in a while.. Well @ least not the inside anywho so I can't really tell ya one way or tather on da birds..:chuckles:

Have you checked back at the window element where the power is connected? My connector had broken off. I'm assuming from repetitive closing of the hatch, but only separated enough to break the contact and was not easy to see.

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Originally Posted by pajeff02

If your car utilizes the same switch as our Firebird, I can PM you the wire diagram and pinpoint tests to diagnose the defroster.

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it should. as long as it is the 98-02 model years. I know prior to that they where different.

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Originally Posted by jad628

Have you checked back at the window element where the power is connected? My connector had broken off. I'm assuming from repetitive closing of the hatch, but only separated enough to break the contact and was not easy to see.

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yep. no voltage at the element connectors. The element looks good to me. The wires and connectors look good too. i pulled off the hatch trim, looked good underneath too.

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Originally Posted by pajeff02

If your car utilizes the same switch as our Firebird, I can PM you the wire diagram and pinpoint tests to diagnose the defroster.

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ok, here is how my lazy lame butt posts pics, :)

http://www.cardomain.com/ride/2954870/1

its at the bottom of the page.

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Originally Posted by kool-aide

ok, here is how my lazy lame butt posts pics, :)

http://www.cardomain.com/ride/2954870/1

its at the bottom of the page.

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Just printed the pic to take home with me tonight. I'll dig into the books and either post a reply or send a PM.

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Originally Posted by pajeff02

Just printed the pic to take home with me tonight. I'll dig into the books and either post a reply or send a PM.

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cool thanks

PM sent.

so it seems like even one break in the rear element can cause the whole thing to fail. Would this be an accurate statement?

well after reading the list of trouble shooting steps.

it states if you are getting voltage at the connect but no defrost and switch light.

you have a bad switch, :(.

this means i have a bad switch and a second u-pull it switch that is bad.

guess i will be saving the big bucks for a brand new switch.

I get voltage in each step of the trouble shoot. bummer, well that's what you get for gambling on used parts, :).

you have to know when to hold em, know when to fold em, know when to walk away, lol...


thank you pajeff02, that PM was just what i needed.

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Originally Posted by kool-aide

well after reading the list of trouble shooting steps.

it states if you are getting voltage at the connect but no defrost and switch light.

you have a bad switch, :(.

this means i have a bad switch and a second u-pull it switch that is bad.

guess i will be saving the big bucks for a brand new switch.

I get voltage in each step of the trouble shoot. bummer, well that's what you get for gambling on used parts, :).

you have to know when to hold em, know when to fold em, know when to walk away, lol...


thank you pajeff02, that PM was just what i needed.

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No problem -- glad I could help out. Now that you have a diagram and know what the wires are, try a jumper and see if it activates your defroster. You can also unplug and probe the back of the switch with a continuity tester to see what you get. I hate to see you invest in another switch.

I guess I could check 0 Ohms vs some Ohms for continuity. I don't think any of my meters tone for continuity like some of the fancy ones, such as a Fluke. Oh I wish I could afford a Fluke.

It looks like you would jumper Brown and Purple. The would be the ignition voltage to the rear defrost wiring. Hey, I could just drive with my defrost on 100%, lol.... Believe it or not I use mine to help warm up the morning dew down here. people think you don't need one in the south, but I find it can help with early morning dew.

At least if I jumper it I should get my 12V at the rear hatch connections.