. . . . So, the defroster failed last winter, then worked exactly once this spring, and hasn't worked since. When I press the knob, the indicator light comes on and the timer circuit does work, but no defrosting action.
. . . .
So what is the circuit that drives this? Is it also in the TIPM, as my non-working horn is? Can anyone give me the wires, wire colors, circuit? While I'm in there trying to get my horn to work, I'd like to address this, also. Thanks.

The rear, heated backlite glass or defogger is powered b;y the TIPM. You press the cotnrol button on the HVAC control panel. The HVAC module sends a unique, coded message over the vehicle network to the TIPM.. The TIPM interprets and energizes the circuit to the rear window heat grid. See attached images for wiring cirucit and TIPM connector pinout.

Images are for 2008 - 2009 Avenger / Sebring so wiring colors should be the same or very close.

 

Thanks! Maybe that and the horn will be the same issue - either oxidation at the connectors, or a failing TIPM.

 

. . . . Thanks! Maybe that and the horn will be the same issue - either oxidation at the connectors, or a failing TIPM. . . . .

I believe the horn issue failing to sound or making a weak sound has been recetly discussed; Sep 7, 2025 at 4:17 pm.

https://www.allpar.com/threads/low-...s/low-horn-failure-2011-chrysler-200.250797/?post_id=1085458582#post-1085458582

If this is correct below is diagram showing TIPM horn wiring and pinout for TIPM connector C11. Make sure your ground connection is good as a poor ground will make an otherwise good sounding horn become weak.

 

As you move the (+) probe towards ground, the voltage should drop towards zero.
If it stays high (12v) across the grid, you have lost ground.
Use care with the probe tip not to scratch 'open' a grid line when testing. Some cars use the upper grid lines as a radio antenna. These lines won't have power.

 

I measured at the connections to the grid, was not touching any grid lines. I had to push the interior panel back a tiny bit to get at the connections. Will check again when I get a chance.