rear window defroster

There is a defogger relay that sounds like it is not working. Here is a wiring diagrams and a guide to confirm the issue.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

The connectors for rear window defrosters are traditionally either at the bottom of the grid on both sides, top of the grid, or on the driver's side of the grid, visible just by looking at the rear window from inside the vehicle.

Oh, and make sure there is power on both sides of the switch when the switch is enabled. The switch could be defective internally, allowing the light to turn on, but not passing power out of the switch.

Check out the diagrams (Below)

Please let us know what you find. We are interested to see what it is.

Cheers

Remove the passenger front kick plate, remove wiring harness, pull harness apart and usually the (2) purple wires you will find burnt, just run a jumper wire across from one side of harness to the other side, problem should be solved. good luck

Hey,

Great addition to this thread! Please feel free to help out on the site whenever it can add information that will help.

Best, Ken

When you push the switch the switch lights up but the rear window defroster does not work, bur if the car is started with the remote start the defroster does work until you turn the key on, then the defroster quits working

check items in pic if both are good and I'm assuming fuse will be have scanned for codes it may be control head causing problem.

Electrical problem
2007 Chevy Impala 6 cyl Front Wheel Drive Automatic

The rear window defogger has stopped working, the indicator light comes on but the window never defrosts. I have checked the connections at the window and they appear intact. The window stopped working at the exact same time I had a rear break light and blinker light go dead. I replaced the lights and they work fine so I guess it was just a coincidence. Looking for any other suggestions. Is this possibly a bad fuse or poor connection somewhere? Thanks for any help you may be in advance.

Hi there,

Carefully undo the wires at the gird, place a test light between the wires if it lights up the grid will be faulty, these can be repaired if not to bad, check this out first.

Mark (mhpautos)

window element registers 12 on200k ohm scale and measures 4.6 volts at wire leads when disconnected from element. but won't defog

Voltage to defog needs to be around 12.6 volts. Check for pinched or cut wire.

I have tested everything from the fuses to the rear window. It all came down to the relay once replaced the defogger works great.

here is apic enclosed, it's the right ip junction block.

For past month my blower motor will just cut out...may last a day, may last a minute, then it will randomly come back on. In conjunction with this i have lost my rear defrosters. Any ideas?

Do you still have the stock radio installed in the car?

Yes...it's stock radio

I haven't had the recall on the ignition switch fixed yet either...

Are u going to help answer my question or did I waste 5bucks

Hello, sorry for the late reply. Sometimes my email notifications go to my spam folder. Thank you also for you donation.

Is the blower motor control and the defrost button on the same control head?

If you remove the passenger side kick panel where the inside fuse box is, you will see a white connector below the fuse box. Disconnect the white connector. If your defroster isnt working and you dont have 12V at the rear window, your problem is most likely that this white connector burned out.

Electrical problem
2004 Chevy Impala 6 cyl Front Wheel Drive Automatic 33000 miles

can I sodder the rear defrost tab back to the window,were the plug connects to the window ,the sodder broke and now the defrost does'nt work

You can glue it back with special conducive epoxy type of glue.
Google 'rear defrost repair'; you'll find plenty of website telling you what to do.

rear defrost does not turn on

With a multi meter check for an open circuit on the demister grid, check switch operation, check for power at the switch and power at the grid, start here.

Heater problem
2001 Chevy Impala 6 cyl Front Wheel Drive Automatic 71000 miles
----------------------------------------------------------------
My rear defrost has stopped working. Any idea what could be wrong? The light on the dash says it's on but the window doesn't get warm.

It could be a broken wire in the window grid. You can find it by turning the defroster on and wiping fine steel wool across the grid. Look for small sparks when doing this. This will pinpoint the break in the grid. Repair kits are available.

Electrical problem
2004 Chevy Impala 6 cyl Front Wheel Drive Automatic 42000 miles

Rear window defoster does not work.
Light comes on when button pushed. No noise at relay. Have power to relay on upper right terminal. Left upper right terminal when engine is started.
right lower terminal changes in resistance when activating defrost switch. no change in left lower.
Relay has been replaced and breaker was changed out with power seat breaker with no change. No power to grid on rear window when switch activated.

Hi Wayne Boren, Welcome to 2carpros and TY for the donation Check the HVAC control module rear defog relay control circuit and the radio antenna control module-see diagram below

I mentioned in my email that I already have the diagram. Your diagram is unreadable an is too small to see detail because it is blurry. I was hoping that you could give me some pointers based on what I have check. The antena module does not affect reception as other people have mentioned. If I have power to the relay (and it has been replaced) then why doesn't it click when the button is activated?

I'm not aware of any email you have sent-I was asked to assist here-If you have the diagram-

Check the body control module it powers the coil side of the relay and the HVAC module grounds it -also the defog circuit goes thru the antenna module before it hits the grid-inspect the grid for open

Do you need special equipment to check the body control module? I mentioned earlier that their is pwr to both top pins on the relay. Left side is for the coil so that tells me there is power. Does the body control module act as a ground to complete the circuit?

Its the HVAC module that grounds it-that's if you got power on the coil side of the relay

Yes you do -to check the BCM and the dealer has it

I think it is the HVAC control module because a jumped the circuit across from the always hot to the rear window and it worked. Athough I would not recommend a paper clip because it get red hot. The relay is misleading because it is not set up the same a the diagram. It is in an X pattern. I will take it from here.

rear window defroster does not work even with button on (light lit up ) on 2002 chevy impala with small v-6 and 122 thousand miles

My rear defroster is no longer working. It barely worked for a while after I bought it in Jul 2006 (used). Now it's stopped working completely. I did have the battery replaced and it's possible that's when the defrost stopped completely, but I can't positively correlate the two items. I've also replaced the Rear Window Defroster Relay (passenger side fuse box) and that didn't solve my problem. I've checked grid continuity and I get 0 ohm reading (no breaks in the grid). I get 0 Volts across the connectors when the switch is on. The indicator light is illuminated when the switch is on as well. What should I check next? Thanks.

Very wel,l you got the basic idea on what's going on

Heater problem
2003 Chevy Impala 6 cyl Front Wheel Drive Automatic 89800 miles
----------------------------------------------------------------
What causes this fan motor to act like this: Sometimes when I start the car the fan runs normally. However the next time I start the car the fan will not run at all and the cruise light is on in the dash (even though the cruise is not on).Also the rear window defogger malfunctions.Then If I put the fan control to the highest setting the cruise light will go off but no matter what setting the fan control is set at, usually around 15 minutes driving time, the cruise light goes off and the fan motor turns on all by itself and everything starts working fine again. The wife thinks the car is Haunted!!! I said nonsense, lets ask someone who knows something.

Replace the ignition switch assembly. There is an intermittent loss of voltage on one of the circuits. I have seen this problem on multiple impalas

Hey dennyp thank you for your response. Is this some- thing I can do at home or strictly a dealer repair. Since the key is on the dash of this model I know it can be very difficult to get behind the dashboard. I imagine that's were the assembly is. Is it possible for a pretty handy "home mechanic"with plenty of tools?

I would recommend taking to the dealer since there is a possibility it could need theft system programming after the repair. It is also somewhat difficult to get into the dash. The repair procedure is too much info for me to post on here, so if you do it youself have a repair manual handy.

fan motor and rear window defrost don't come on all the time mechanic says it needs a ac heater control head which is 475.00 could it be anything cheaper

Make sure they have checked the switches. The rear defroster and fan motor are on different circuits.

where is the rear defogger switch to turn on and off on my 2008 Impala